View Full Version : freewheel differential

02-08-2011, 11:43 PM
1, this is not my design I just drew it.
2, I have not built this but cannot see why it wont work.
3, Its not a proper differential but does allow both wheels to drive, BUT, the outside wheel will freewheel round a corner rather than drive round a corner like a real differential. Not a problem unless you want to spin on the inside rear wheel.
I hope the drawings are self explanatory.

02-09-2011, 03:53 AM
Hi all

I my be wrong here but I though that if one wheel was slipping say on sand or gravel then the differential could not drive the other wheel ?

So why hanker after one that only drives both wheels under idea conditions , in other words when 1 wheel drive would do anyway ?

I assume the picture above would only have this problem if when cornering the inside wheel had no grip so it is maybe better than a differential under most conditions ?

regards Paul

02-09-2011, 04:26 AM
Thats where I believe the strength is in this design. If one wheel slips then the other will still drive.
If the inside wheel slips in a corner the the outer wheel will drive and vise versa.
If a conventional single drive wheel slips then all drive is lost.

jodi rinaldi
02-09-2011, 05:16 AM
HI All, you can see at below addres, how differential work

how if gear cassete use for gear differential , replace bevel gear


John Lewis
02-09-2011, 08:19 AM
The Penninger trike worked somewhat like this. It had a freewheel sprocket on each rear wheel. There was a mid drive with a long shaft and a chain to each rear sprocket. This gave the same result as Savarin's drawing.

Sometimes in a bit of pea gravel my drive wheel slips. If its on an uphill it can be a pain. The gravel usually builds up on the verge side which is my drive side. With the two wheel drive setup the other wheel would drive and I'd not have the problem.

The trick is to not pedal to hard when starting off with the whone wheel drive to try and stop the slip starting in the first place.


02-10-2011, 03:19 PM
Hi all

My Hase Kettwiesel has one wheel driven , the right rear wheel , as I live in the UK that keeps it out of the gravel and so it is liveable with.

One annoying problem tho is that it cannot be ridden hands off for very far as it tends to steer away from the driven wheel , especially noticeable up hills and probably made worst by me not having pedals for cleats ?

regards Paul

John Lewis
02-10-2011, 09:16 PM
Interesting that the Kett steers away from the driven wheel. That would mean it is running up the camber to the right. and the drive is on the right.
My DeltaWolf drives on the left and seems to have no tendency to run up the camber. We ride on the left as in UK.
I had read of this phenomenon with the Kett previously and have tried the Wolf on the flat, on hills and on normal cambers and it runs true without a tendency to try to hop sideaways or steer off.
Makes me wonder what is so different between the Kett geometry and the wolf. I wonder f the 26" rear wheels on the Wolf have something to do with it.
Must say I really like the Kettwiesel from what I have seen of it on the net. I'd like one with the differential. Only thing that stops me getting an Anura that is similar to a Kett is the tiny 16" I think wheels.


06-20-2011, 04:02 PM
Thanks for the inspiration.
Having been working on my quad i took the plunge a couple of weeks back and converted the drive to incorporate freewheel differential as the pictures show in saravin's first post.
It just so happens that an old roller from a roller conveyor is exactly the right bore size to fit over the 2 freewheels i had (bmx type), then welded 5 short lengths of 6mm stud to outside of the tube to drive the freewheels.
The centre driven cog was another old freewheel which i took apart, fitted the tube over and welded from the inside.

So the finished assembly is two tubes welded to the old freewheel on the inside, with the 6mm studs on the outside.

It all seems to work fine.

The big plus was that I was able to get the drive train from the pedals, to an old spindle with 7 speed cassette 11-32 then mounted another old freewheel to the 6 bolts that would hold the disc brake on the other side of the spindle. By mounting the spindle above the boom means the derailer has really good ground clearance only about 1inch lower than the steering control arm.

Then direct chain drive to the rear on the left hand side.

Thanks again, just another few tweaks to fit front derailer, then painting time and then i will post some pictures

06-20-2011, 09:35 PM
Excellent news, cant wait to see the pics.

John Lewis
06-21-2011, 07:02 AM
Looking forward to seeing the pictures. Sounds good.


01-15-2012, 04:41 PM
wow has it really been 6 months since last post.
In that time have built a koolkat recumbent and a chopper.
But back to the quad.
I was not happy with the final handle bar position, so some more modifications required, but i had promised some picture so here they are for now.

07-30-2012, 03:00 PM
Hi savarin,

just thought i would give you where i have got to.
Just added an explaination to http://forum.atomiczombie.com/showthread.php/6669-Was-brainstorming-today?p=63849#post63849
The finished unit works great, have just incorporated it into my back seat driver project http://forum.atomiczombie.com/showthread.php/6195-Back-Seat-Driver?highlight=back+seat+driver, which is a tandem trike for me and one of my kids, have a look if you get the chance

01-09-2013, 04:47 PM
1, this is not my design I just drew it.
2, I have not built this but cannot see why it wont work.
3, Its not a proper differential but does allow both wheels to drive, BUT, the outside wheel will freewheel round a corner rather than drive round a corner like a real differential. Not a problem unless you want to spin on the inside rear wheel.
I hope the drawings are self explanatory.

Very good design, it closely resembles the Weismann locker used in some racing cars. Your diagram gives me a far better idea of the operation than the description given in 'Tune to win' by Carroll Smith.
My wife has just acquired a tricycle, so I might just try to build one myself.

01-09-2013, 07:58 PM
Great diagram its crystal clear. Nice set up.

01-09-2013, 09:29 PM
This design has been discussed many times before, and is certainly not a new concept. Something very similar was used in the center diff of the Jenson Interceptor 4WD years ago! It is BETTER for our purposes than a "proper" differential ! The only reason we need to fit a diff is to combat wheel spin.
One wheel drive is not a problem 99% of the time, and it does not really matter which wheel drives a trike--until it slips.
Here a proper diff fails completely, as all drive is lost. The ratchet or freewheel diff wins because if one wheel slips on a hill, insantly both wheels are trying to drive. It may also tend to be self steering, as the inside wheel does the driving, but I have no proof of this.
It is the only cheap and light weight device that I know off that will work on our trikes.
So there is no need to appologise for it not being a proper differential---for us it is the only one worth using!
Steve G

01-10-2013, 05:58 PM
Just a quick note to add it works as described by Ticktock, couple of pictures of my finished unit.59925993

The centre section is actually two sections of tube from a roller conveyor, which was a snug fit over the two freewheels to the left and right. The centre drive is welded to the two tubes on the inside. On the outside of the tubes are m6 stud to act as drive dogs on the two freewheels.
The two free wheels are as the freewheel adapters that Brad now sells.
So for an easy freewheel differential drive as per the start of this thread and all credit to Savarin, you only need to really build this centre section, two tubes, old cog from a single speed freewheel and some 6mm bar or stud.

01-20-2013, 10:06 PM
This is a really great idea. The question I have is if you are building a loderunner like me how do you avoid the center bearings? Your two inside bearings look at least 10 inches apart, whereas mine are right next to each other. Do you have any problems with the axle trying to bind with that much cantilever?

01-20-2013, 10:33 PM
personally I would place bearing supports on either side of the diff as close as possible to it to keep cantilever as small as possible

01-21-2013, 03:21 AM
Hi demon327,
Yes I am the builder, and to date not had any problems with the unit, but it has not clocked up many miles to be honest.
If you go back through this thread, you will see the unit started out on a quad, that got reconfigured into the yellow tandem trike.
It was seeing this thread by Savarin that caught my attention and I modified the original plans from the street fighter to this design, it also allowed me to do away with the idler pulley on the drive side, which was replaced by a jack shaft, the other benefit being it took the rear derailer out of a what i considered to be a vulnerable position to being bashed, had the quad been used to go off road and hit something. Then likelihood would be miles from home with a broken machine, that is not as easy a normal bike to push.

Bottom line the Savarin design looked a good challenge and would provide drive in slippy situations, so I thought I would give it a go.

01-21-2013, 07:21 AM
Fitting this to a Load runner (1 or 2) should be no problem at all.
You correct that the two inner axlebearings should be as close as practicle to thje diff-but an inch or two is not going to bend a 20mm axle.
As to the diff center, it may seem a strange answer, but the longer this the better! the length will help to cancel out any in accuracies in the axle positions.
I doubt any of us could get the two axles absolutely dead straight and in line both vertically and horizontally.
The layout used by Charlie R does overcome this problem, but with a bit more work!.
My guess, if I built it this way would be with the two freewheels about 8 to9 inches apart, and the bearings within 1 inch of the freewheels.
If I was using the same setup as Charlie, I would keep the freewheels as close to center as possible, and use longer axles
The inner bearings would need seperate supports, each made the same way as the single one on the original load runner, being welded to the front cross member (going from memory on these plans)
disc brakes fitted between the bearings on each axle.
Charlie has already posted one report of using this style diff on ice and snow, and it worked fine---as expected.
Steve G,

01-21-2013, 08:46 AM
Hi fellow Zombies :-D

I'm planning for a Timber Wolf as my next project.
I've been following this easy turn - lock diff with great interest.
I have completely stolen the basic concept from this thread and modified it slightly
I have a plan that looks like this (sorry about the pour sketch, but have to make do for now):
The plan is to include a freewheel hub so I can use the easy turn lock diff in combination with normal derailleur and avoid the mid drive.
For the timber wolf I think this is optimal when it uses 26" rear wheel.
To do this I need to transfer the the power to the end of the "housing" which can turn freely on the shafts i have made 0.5mm gap between axle and housing end covers.
I plan to fit a grease nipple as well and "fill" the housing with grease to increase lifetime and reduce noise from the unit.
The housing "rings" that will clamp the sprockets (bolts will take the torque as such) is to be made of nylon or aluminium depending on what I find.
Left end cover will most likely come from an old cutting board or a piece of scrap aluminium.
Right end cover and freewheel hub connection will most likely be steel as that is easiest to get my hands on.
Then when everything is assembled the housing can be painted so it looks like 1 unit only.
My dream is a do it myself and get a look that looks like done by exuberant expensive professional company and as Brad says: I build it myself :-D

This design is by all means easiest if you have a lathe or friends that can help with same but I think it should be doable :-D
At the time being I can't test my design as I don't have any parts to build with.
So this is just a suggestion to another way of getting the easy turn - lock diff in service.

I know this will not fit the Timber Wolf as is due to the swing arm design, but there should be ways around this as well :-D

I hope this can be an idea to some Zombies :-D

01-21-2013, 09:15 AM

Nice adaptation of the drive!

One question, though. Is the cluster freewheel bushed around the shaft, with only the BMX freewheels pinned?

Using your adaptation would eliminate my extra jackshaft, and save me a few lbs of extra weight, along with the drag of the extra components I have in my drivetrain.

Nice work!


01-21-2013, 10:20 AM

Nice adaptation of the drive!

One question, though. Is the cluster freewheel bushed around the shaft, with only the BMX freewheels pinned?

Using your adaptation would eliminate my extra jackshaft, and save me a few lbs of extra weight, along with the drag of the extra components I have in my drivetrain.

Nice work!


Hi and thank you Charlie :-D

I hope I get the question right, my English isn't the best in the bicycle technical terms ;-D

I plan just to let the gear cluster sit on the end cover/adapter like normally done on the version Brad designed.
As I don't have any parts that I can play with this is purely fiction for now, so I hope it works :-D
There should not be a problem in making a bushing in brass and in this way control the flexing of the shafts even more, but I don't think it is needed.

I actually think that I might have to reduce the shaft diameter just where it enters the cluster as I can't get a 20mm axle through here.
That is not on the drawing :-/
I can easily modify the drawing for this.
As I said I don't have any parts out here on the big ocean, so I have to rely on my memory and it is maybe 15 years since I last opened a threaded gear cluster.
Can anybody help me in respect of the biggest size axle that can go through the cluster without problems??
My guess is around 17-18mm to which my shaft must be thinned for the last piece that is going through the cluster into the freewheel hub adapter in left side.

Yes I plan of either pin or press fit the "BMX" hub to the axles which should give a nice smooth running I hope.

I really hope this was helpful and answered your questions.

Please let me know if something here doesn't add up as I can't produce the unit right now.
I plan to use 14teeth BMX 30mm freewheel hub (instead of the 1,375" 24tpi version) thread hubs to decrease the diameter of the unit to an absolute minimum to make it look nicer and save weight as well.

Thanks again, and I just can't wait to get home and get some parts between my fingers.
This is for sure the first thing I will make for my timber wolf as this can influence the rear swing arm quite a lot depending on the size that I can get working.

Ohhhhh, why do I have to be on work I want to build..............!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!!!!!!!!!!!!!!!!!!!!!!!!!!!

01-22-2013, 06:20 AM
I see no reason why it will not fit on the Timberwolf, or any other AZ trike! You may (will) have to move the inner bearing mounting arms to suit the new diff, but as you are building the diff first, its easy to put them where you want them.
A very nice addition to a design that has developed on this forum. This is probably as far as it can be improved and still keep it within range of our workshops / wallets.
A 20 mm axle will pass through a 14/28 or 14/34 Megarange srcrew on hub. There is an 11/34 Megarange screw on avaivable, but I doubt that this will
let a 20 mm axle through (not tried--just a guess)
I see no need to thin a 20mm axle if you are using all "normal" screw on parts and AZ type adaptors, as it will pass through all these easily.
And the drawings are good enough to start making one right now if you have all the bits!
Steve G,

01-22-2013, 07:52 AM
Hi Ticktock :-D

Well as you know this is intended for the timber Wolf, and yes I need to move the bearing support/swing-arm compared to the original design.
I think I have five different options that I sketch on during spare time ;-D.
But to be honest I really really would like to get going making this easy turn lock rear differential.
I can't wait to get my fingers in the parts and materials and get going :-D

Thank you, yes completely stole the system and tried to adapt it to my purpose. I really hope this can be of good use for other than me.
I just hope that I get to finish it first :-D
I really hope this will work with the 20mm axle as originally intended. I have no plans of making the axle thinner if not needed :-D
I just think it is possible to get it working but once I have the parts that decision will be take :-D
Just need to start sourcing parts :-D

I will try to get some parts when I visit USA early next month as some parts are really hard to come by in Denmark/Europe.

Thanks for the nice critique from a very experienced builder :-D

By the way I'll be in south China soon, but just for a ship visit, so no going out or anything.

Do you have any links for the 11-34 mega range screw on ??
I haven't seen that option anywhere yet.

01-22-2013, 11:52 AM
Amazon is a great source for the 11 to 34 mega range Cassettes- They have 7-8-9 speed cassettes available and I have even seen a 10 speed cassette.
As all these cassette screw on the the same freewheel adapter they should not have an issue with a 20mm Axle. As to the BMX freewheels I am unsure what their dimensions are so I am unsure if they will fit a 20mm axle.
But here is a quick find from a simple Google search. Hope that helps.

By the way that was a really neat adaptation from the original idea.. The bad is if I decide to add this to the Timberwolf in Progress I will have to remake my Axles as mine were originally formed from the Delta Runner plans in 2008. Not that I need a differential here in Arizona where I live doesn't get snow. It gets cold but no snow. We reached 27 degrees F. the other morning. That - 2.7 C for all the other Outside USA Temperatures. And while that may not seem cold to most of you folk you have to realize that 43 C or 110 degrees F is a nice summer day for me here in Arizona. And we consider 65F or 18C cold enough to warrant winter jackets.
Anyway off the subject of a differential- I hope you find what your looking for. I suggested Amazon as I know they have European links and will ship to Europe as long as your country does not prohibit it.

01-22-2013, 05:20 PM

Great drawing & a neat solution to a good system. However, I do see (or maybe misunderstood?) a minor design flaw in the post.

If the unit is pre-assembled before fitting, and assuming it is fully enclosed (you did say you may fill it with grease) then there is no access to pin the axles to their respective freewheels.

If the unit is not pre-assembled you would have to be sure to have all the components are over each axle in the correct order before pinning the freewheels.

Does this make any sense or have I missed something?


01-22-2013, 07:12 PM
I'll try to answer that one, Ken.

It would appear that you would need all the components slid onto their respective axles in the correct order as you thought, and then assemble it in this order, at least this is how I would do it:

pin bmx freewheel adapters to axles

install bmx freewheels to adapters

slide outer cover over bmx freewheels

install bolts through end cap and cluster freewheel adapter (which I think should be bushed so it can slip on the axle) through cogs on bmx

install gear set freewheel onto adapter

slide bearings to their respective mounting areas

ride and enjoy!

Is that what you were asking?

Bushed or not, the cluster freewheel adapter should be a good fit to the axle and would not need to be pinned, as all output torque would then have to go through the bmx freewheels. This would have to be made a slight bit different than a regular adapter to give room for bolt heads. Not sure I'd use flathead bolts for this as I think this would reduce the amount o expectations?Does that meet yourf torque that could be safely transmitted to the bmx freewheels. I'll leave that to my betters at engineering.

By the way, Penola, your drawing shows the bmx adapters in the wrong direction unless you are wanting left hand thread freewheels. Otherwise they would tend to unscrew when torque is applied. The endcap should also be made from 3/16 ~1/4" (5~6.5mm) steel flat stock as it functions as part of the torque transmitting member. It could actually be welded to the case, with the freewheel end of the case notched in some form or another to match notches/gaps in the freewheel adapter. In the original drawings, the spacers fill two roles. Support for the through bolts/pins, and torque transmitting members. The case in your adaptation would have to fill this role, much as the center section of a normal bike hub serves this same function.


01-22-2013, 07:55 PM
Hi darnthedog :-D

I'll have a look around, I guess I just never thought that the Mega range was available i screw on version :-D'
Thank *** for the help and knowledge available here, not to mention the free sharing of info :-D

Thank you :-D
He-he sorry if I caused problems in your build ;-D
Well I just played this thing up while planing for my Timber Wolf on which I'd really think this ease turn lock diff will come in handy for a trip in the wild as well as for winter touring :-D
OK I first have to build it all, but Warrior almost done then this is the next project.
Ref SWAMBO some parts have arrived at home so I can start when I get home :-D

I admit that half of the fun about the fun with this diff is to build it and make it work :-D
I hope to find a bunch of free wheel single speed for normal 1,375"x24tpi units which I can get for a good price.
Then I have some handy as I can see 3 diffs being needed in my future if I get 1 to work alright :-D

I soooooooooooooooooooo look forward to get home and work on this project :-D
I do have an onld 7 speed cluster that I can use for testing, but I need to make the axle adapters and get the freewheels to fit before anymore can happen here :-D

Thanks for the help :-D

01-22-2013, 08:44 PM
No links--I just remeber some one saying it was available, I think on Ebay, which means any good bike shop should know of them. But I have my doubts that a 20 mm axle will pass through this hub. You would only need to thin one axle, and use different adaptors if that was the way it worked out.
You would have to use a screw on hub to make this diff easilly-.
South China is about 2000 K from here, so I am afraid we will not meet up---next time!
Steve G,

01-22-2013, 09:05 PM
You are right Charlie--sharp eyes! The free wheels are on backwards! No big problem as the principle is the same.
After another look, I think some form of bush is needed between the case and the axles at either end, and , as I have access to a lathe that can do it, I would alter the design slightly, and add a proper bearing at each end, which would effectily seal the casing.
I see no problem with the casing withstanding any torque we can apply, but I would use high grade bolts. If the nuts are placed between the adaptor and the cogset, it will be possible to completely assemble and disassemble the unit with the hub still screwed on to the adaptor. This is important for any roadside emergency, as it is unlikely that you would be able to remove the hub on the side of the road!!!!And you could use Allen key bolts.
Assembly must be done in the righ order, but it is quite practicle, and once built, this thing should last for years. An ocasional check on the bolts for wear(another reason for reversing the position,) would be all that was required. If the bolts do wear, they can be replaced one at a time, without disassembly of the complete unit
We are on a winner here.
I will try to knock up some drawings with numbers that suit metric and imperial stuff later.
Steve G,

01-23-2013, 08:34 AM
Might be a possible revenue stream after extensive real world testing?

Spline the bmx adapters/shaft ends, and let it free float? Or use snap rings/split collars on both axles to maintain position relative to the trike frame. You see where I'm going with this.

Penola, you created a monster, here. Fantastic! An alternative to Samagaga style differentials that can be an option that any trike/velo builder can use. Lightweight, yet robust.


01-23-2013, 09:25 AM
Hi darnthedog :-D

I checked your link, and that is for casettes not the screw on model, but I did find som 14-34 mega range Shimano that looks just right for this project.
Shimano model is: Shimano MF-TZ31 Tourney Freewheel (14-34T Mega 7 Speed)
I'm not sure if the BMX hubs will fit that good, they have an 30mm thread, but I am ready to try but you can also find plenty strong ordinary free wheel nubs that fit the normal 1,375" x 24 tpi as we normally use.

He-he, I'm sorry that I disturbed your build ;-D
Yes I'll look through both E-bay and Amazon as I have a contact in US whom I will visit in a few days and he will keep my ordered parts for me until I can bring them home :-D
Lucky for me I think :-D

01-23-2013, 09:31 AM
Hi Ken :-D

Thank you :-D
You got it all right :-D
Charlie got it more or less as I think I will do it.
I plan to fit a grease nipple but I haven't decided where so it's not in the drawings as of now.

01-23-2013, 10:12 AM
Hi charlie :-D

Thank you for the help :-D
I plan to make a press fit with the adapters in combination with a pipe split I think, that should give a very strong and clean solution :-D

In my drawings/mind I have made a 0,5mm gap between the axle and the 2 end covers.
That should by all means give enough room for free movement but not excessive play so it looks bad.
I need the end covers to move freely on the axles

You are absolutely correct, I forgot to double check the brain before putting it on paper :-D
I am working on a drawing where they are positioned correctly (luckily it isn't a major change pheeww!!!)
Thank you very very much for putting my attention to this :-D

Yes I think of aluminium for distance rings and left end cover and mild steel on the right end cover/adapter.
I would use a 10.8 or 12.8 bolt which is very strong.
I have planned using a 16 teeth freewheel and fit a bolt in every second groove.
If this isn't up to the task I'll be surprised :-D
By making the torque elements in the outer shell there are posibility for a very high torque transfer.
I sincerely hop it works alright :-D

Once again thank you for your help with the adapters/freewheels :-D

01-23-2013, 10:17 AM
Found a Freewheel cassette which is the screw on your looking for 11-34 mega range.


As to modification of my Timberwolf it probably won't happen as I said I have no justification for 2 wheel drive as I have no ice or snow to worry about here. Nor is there any chance I will be taking this trike into that type of climate in the near future.
As to my research link from before I forgot to put freewheel in the search but I did find the one for you. Although I am sure you could have found it yourself. I am also watching Brad Velomobile with interest as it would make my early morning rides more comfortable. But as it is a commute to work I will probably go with the Timberwolf due to large wheels will get me there a bit faster with less effort.

Sorry about the mis-direction to Amazon. They have a lot of bicycle parts was my actual goal to assist you in getting parts.

01-23-2013, 10:17 AM
Hi Ticktock :-D

That's OK, I managed to find the 7-speed mega range as screw on version :-D
I'll see how it works out once I get some parts to play with :-D
If I need to reduce the dimension it will only be on the right axle as you say :-D

He he, yeap I now China us mega big :-D

01-23-2013, 10:24 AM
Penola and Charlie,
Did some quick drawings, and a ball race version is a real goer--just fell into place!
Sketck attached is a photo of my computer screen, as the printer is doing what printers do best--not work! Deltacad is great for drawing, but no good for sending drawings unless everyone has Deltacad! So , heres a real screen shot.6054
Uses 18 tooth freewheels, (black), and 20x42x12 bearings 60042RS. Only minor changes if you want tom use Imperial bearings.
The ball bearing in the center is the cheapest wayI could think of to take away end play (It was used in older tractors, so it should last with us)
Ideally the right side cap would be better in steel, but as Brads adaptors appear to be lasting out, good grade alloy should work.
The rest of the casing can be alloy. I have not shown the locking bolts on the internal adaptors -just lazy-we all know they are there.
The locating lips on the casing parts make it impossible to assemble the wrong way, and also do locate the bits! The two dowels will line up the casing parts to help get round any errors in drilling the bolt holes.
Assembly in the right order, and carefull axle alignment, and start riding.
In the rush to put this on paper(screen) I forgot to use layers, so it will be redrawn later to dimension parts, but it is around 4 inch /100mm diameter.
Compare with the 14/28 hub drawn full size. I don't think it will work with the 11/34 cassette type hubs, but it will work with the Shimano hub you found (I have already fitted these to 20mm axles)
So now we one better than Samagaga, as this does what we want, not what they think we want!
To be fair, they aim at a different market, and the larger trikes here do need a normal diff, as the extra width would make steering just a bit difficult with one wheel drive.
quite a big step from what it started as, yet exactly the same !
Steve G,
PS Wish I had done these drawings before I went shopping for other metal today--I would have grabbed some alloy at the same time! Now I have another 50 K round trip to start building one of these . (The trike does need to used, and --More ice in the beard)

01-23-2013, 10:40 AM
Hi Ticktock :-D

Yes thank you Charlie for your sharp eyes :-D

I don't think a bearing in each end cover is really needed here, but if I find it needed after building and testing then I will fit a grease lubricated brass bearing as there are hardly any difference of speed between the shaft and the end covers.
Ball bearings will not last too long in this setup whereas a old fashion "slide" bearing will be perfect here (at least in my opinion).
This is also easy to press fit into the end covers and a polished brass in both ends will look stylish ;-D

Yes I think this will work out fine in respect of power/torque transferred at least from my humble body :-D
Considering charlies post and your latest input on the bolts then I'll draw a little more tonight :-D
Actually we can take away the nuts if we cut a thread in the right end cover instead :-D
I like the idea to be able to inspect and hange the bolts when needed (if needed :-D), so this is included in the next drawing as well :-D

I like this, I sincerely hope this works out well :-D
Thank you for your valuable input :-D
7 high strength M6 allen bolts should absolutely do it alright I think especially because they are fitted at a decent radius :-D

01-23-2013, 10:46 AM
Hi Charlie_r :-D

Yes splines would be groovy but out of what I can handle in my workshop :-D
The idea is fine but I don't have the tools :-/ (crying like a baby).

Thanks a lot, I love if someone or "manyone" ;-D could have good use for this should it work out as intended :-D
Yes I have looked at these stupidly expensive easy turn lock diff from the few suppliers, and at these prices we can build the whole bike including this hopefully great unit.

I can see that many people look and chime in, this is the way to a great design :-D

Thank you for your input :-D

01-23-2013, 11:01 AM
The reason I opt for ball bearings is that, although you are correct that there is little speed difference between casing and axle when it is acting as a diff, ie you peddling forward, there is a huge difference when you are not peddling--freewheeling. Also, the pressure is quite high, and in a dirty enviornment, I think the brass bush will not last too long, and nither will the axle! What happens is that the dirt gets inside the bush, and instead of destroying the bush, it tends to embed into the brass, and turn the brass into a grinding disc, cutting up the axle! We see this happening all then time with clocks.
Hence the strong recomendation for the bearing--it becomes a sealed unit this way. And the bearing will last provided you are careful with axle alignment.
I did not try one, but the sprocket looks more like 7mm which is what I have drawn, but 6mm should be no problem as there are six of them, and I doubt we can shear them all at once. Worn bolts can be replaced, and the freewheels, if worn at the teeth, just moved round one tooth, as the bolts stay in the same tooth space all the time--gives three life spans!
I do not advise designing with a thread in the end plates--a damaged thread could result in a need for a new plate, whereas a damaged nut and bolt is cheap and easy to fix . If the casing ever came loose, you would do a lot of damage to threads cut in the end plate, instead of just having to tighten the bolts again! I did not show any details, but I would be using self locking nuts on these bolts.
Steve G ,

01-23-2013, 11:05 AM
Thank you darnthedog :-D

Absolutely no hard feelings, I'm sure you tried to help, just look at me fitting the freewheels in the wrong direction :-D
I found them after Ticktock told me that I could find the mega range for the free wheel screw on system.
I always learn something new which is very nice :-D

That is perfectly fine, why should you make a more complicated and heavier build than needed.
I just want this because of my intended riding areas as well as some really annoying types of weather here.
I also ride in pebbles at times where the Warrior suffers big time with the 1 WD.
The I quickly engage my 3WD (2 hands pushing on the front wheels as no fender to obstruct this stone age 3WD :-D)

All the best :-D

01-23-2013, 11:48 AM
Hi Ticktock :-D
Yes, I just assume (might be completely wrong) that the internal "friction" and masses will make the diff move together with the axles and let the (hopefully) smooth running freewheel cluster do the freewheel part.
We will see, I plan on testing this out a little when I get parts and time for this little project.

I just fear ;-D that you will beat me by quite a margin to finish 1 or 2 of these up for testing in the real world :-D

At sea we use the slide bearings all the time and have no problem that a healthy dose of grease can't fix ;-D
However a narrow bearing would be easy to fit in the end covers as you suggest.
I will however try the simplest solution first and see how it works out.

It might broaden the range of builders who can do this at home :-D
Whatever we technical freaks mix up at home is our own case :-D

The ball in the middle is a neat Idea, I just think I'd fit 2 small bushings and a pin so the alignment of the axles are a little less critical plus there will be a little less side loading of the pillow block bearings.
But I think your system will work out fine but best on a system with angled bearings as used on cars and tractors to accommodate the side loads :-D

Yes as you know I started with the bolt and nut system but going for the nicest look then the fancy end cover is possible :-D
I also think I will do the job with bolts and nuts.

I like the idea with the "lips", as this is easy to make and will ensure perfect fit.
I was planning to use very close fitting bolts but your idea is neater :-D
I will work that into my drawing later.

I have made a little update on my drawing as well.
I like that you help me out as you have parts and much more experience than me in this area :-D

I think this might very well end up being a nice solution that many can benefit from without having to pay 500+ $us for a diff that also need special shafts etc.
I do't know the price of the materials etc for this item, what is your guess??

All the best, and I hope you get a well working nice looking diff out of this :-D

01-24-2013, 05:44 AM
Please don't think I am being over-critical. once again - brilliant design & this is just the place to iron out the niggles. So here's another niggle to consider.

We have established that the inner freewheels are to be fitted to the axles prior to finished assembly then all the pre-arranged components assembled in order. That's fine, and once fit to the trike it should be pretty much maintenance free.

However (ooh I must love that word, it's in all my posts), Especially during experimentation, modification, testing etc., once the 6 speed drive freewheel is on, the whole lot would need to be disassembled and the axle cleared of that freewheel for the freewheel removal tool to fit should said freewheel need removing.


01-24-2013, 05:49 AM
Here's an after thought to my last post, is there any way the six speed could be fastened to the outer casing without using the freewheel component of it (i.e. loose the screw-on factor). Freewheeling would still be achieved by the internal cogs, a larger exit would be available for larger axles and removal - depending on type of fitting - may not be an issue.


01-24-2013, 07:21 AM
Hi Ken :-D

Hey no problem :-D
Yes it is a little difficult to deal with if you want to remove the small internal freewheel, but not so bad I think :-D
Turn the bike upside down and loosen/remove the diff assembly bolts.
Now you have the "shaft unit" split in 1/2.
loosen the pillow block bearings and lift the left/right half of the drive out

Stolen from darnthedog and Ticktock:
Once your bearings are mounted. Grab a small square piece of metal for each bearing, butt it up tight against the bearing mounts. Then tack it down real good. This piece of metal will act as a reference for mounting the bearings when you pull it all apart for painting or repairs. Ticktock gave us this idea a while back. Bearing alignment needs to be maintained for ease of riding down the road.
Also mark the bearings so the come back in the the same position/direction as when adjusted first time :-D

Loosen and remove the small freewheel adapter and slide it off the axle.
Now a small piece of axle prepared so it fits in the adapter and the other end in the vice (you could also grind/machine the adapter so you have 2 flat sides parallel to the fixation bolt that could be used directly in the vice and most likely my solution :-D).
Now the freewheel can be removed with the correct tool for your model of the freewheel.
The free wheel on the end cover, here I would make a piece of flat bar with 4 holes to which I can bolt the cover and fit the flat bar in the vice and this freewheel cluster can be removed.

This is just suggestions others might have a faster or easier way, but for this job I don't think it's too bad.

If you have the opportunity to make splines in shaft + freewheel adapters then this is sooo much easier when dealing with the internal freewheel adapters but the end cover is still the same issue.

It is in theory possible to the the cluster/cassette directly to the end cover but again I think we will get into the realm of very difficult for most garage hackers like myself.
I want this to be reasonable easy with to do with a minimum of work requiring special tools etc.
With the design as is looks to solve this without going completely out of hands.

It looks like Ticktock will be the first to complete such a unit ;-D
He might have the measurements ready in relative short time, and then we will know how much work is required for such a job.
He might be kind enough to provide measurements for his unit and how difficult it is to set up.
I would love to do this, but it will take me at least a month to get home and acquire parts so i can do this my self.
I strongly feel that Ticktock is far ahead of me, and he have very good idea's to improve the design on his own behalf :-D

For example the guide steps in the rings which is super smart no matter how you decide to execute this system.
The idea of a guide split pin, or and external groove/mark that would ID the original position of all rings and covers to ease assembly afterwards :-D

He-he I really like to participate in this as the input here in this thread is really valuable and improving the design/idea to a level where we can make a really nice and good looking/working little unit :-D
Ready world, here come our own easy turn lock diff that is my goal :-D

01-24-2013, 07:47 AM
Please don't think I am being over-critical. once again - brilliant design & this is just the place to iron out the niggles. So here's another niggle to consider.

We have established that the inner freewheels are to be fitted to the axles prior to finished assembly then all the pre-arranged components assembled in order. That's fine, and once fit to the trike it should be pretty much maintenance free.

However (ooh I must love that word, it's in all my posts), Especially during experimentation, modification, testing etc., once the 6 speed drive freewheel is on, the whole lot would need to be disassembled and the axle cleared of that freewheel for the freewheel removal tool to fit should said freewheel need removing.

Here's an after thought to my last post, is there any way the six speed could be fastened to the outer casing without using the freewheel component of it (i.e. loose the screw-on factor). Freewheeling would still be achieved by the internal cogs, a larger exit would be available for larger axles and removal - depending on type of fitting - may not be an issue.



Good catch!!

You are correct. The assembly would have to be reversed to be able to remove the cluster.

I have that problem even with my mid drive and jackshaft set-up. My way of handling this situation is to have a short section of leftover axle bar welded to a piece of flat plate, and screwed to the workbench. Drilled for my pins, it holds the freewheel mount secure enough to facilitate removal. Believe me, that final freewheel really gets torqued on tight from the multiplication of torque present in any gearset.

I suspect that we will have to make a similar special tool for removal of the freewheel from the assembly.

A few studs welded to a plate would hold the adapter, and if secured in a vice should provide all we'd need for removal.

Yes, it would be possible to lose the outer freewheel. Would save a few grams for the weight weenies (doubt if we have any of those here though!) By disassembling the freewheel, we could weld the cog carrier section directly to the outer cage of the differential. That is how I did the output cogs on both the mid drive and jackshaft on mine.


01-24-2013, 08:08 AM
Again another idea applied during the build to over come thisi problem---just grind two flats on the adaptors parralel to the fixing bolts. Then a spanner (probably your big adjustable one) can be used to hold the adaptor, and the hub removal tool used as normal, Using Brads super strong tool does require that there is no axle in the hole.
Your anwser to the removal of the multispeed hub is the same as mine. All things considered, once built properly, this unit should give no problems resulting in a sudden breakdown. Even if one freewheel fails, you get home on one wheel drive! When was the last time you had a freewheel fail??
I have to re-draw this a bit more carefully to get dimensions (although most dimensions I do know already) so it may be a couple of days.
Have not considered the cost until now, but looking at one multispeed hub, two bearings, and two freewheels and six nuts and bolts I guess about $50 US (based on my guess at cost in China plus a bit) with the alloy as an unkown until I go shopping.
I could calculate the weight, but its cheaper to pick up scrap bits in their shop and ask how much .
To give you an idea as to how creative they can be, I wanted a piece of 5mm plate 200 mm square--they had no 5mm plate, so the guy started to pick up a piece of 200mm suare bar about 1meter long, and said he would slice a bit off for me. Thats when I stopped him, and asked him to slice a piece of 200mm round bar instead, as I was only going to to cut into a circle anyway. 15 minutes later I had a piece of 5mm thick thick , 200 diameter!
I would be surprised if the total cost was over $100 , but you never know until you try.
I was going to answer Kens post, but you said it first, so there is no need to repeat your good words.
Ken--thanks for chipping in with your thoughts, every thing helps lead to a better result--look where this started and where its gone to once we got going!
Now back to the drawing board (showing my age again)

01-24-2013, 12:24 PM
Hi Charlie :-D

That Ticktock is really fast and smart.
I have just drawn the adapter with 2 flat sides as he suggest to use the big spanner on, I would just put it in my vice instead, but same thing different day ;-D

I'll put the drawing in the answer to Ticktock :-D

All the best :-D

01-24-2013, 12:42 PM
Darn it Ticktock ;-D

You are so fast, I've just drawn the adapter as answer to earlier post and wanted to post it as a simple suggestion.
I think we can agree to many things in this build :-D

Here is my latest drawing with following upgrades/additions :-D
I have drawn the control grooves like cones instead, but that is just a matter of taste and tools available.
I have included a small sketch of the grinding of the otherwise normal adapter as Brad designed them.


I a'm very happy that you help out with real world measurements and input here :-D

Yes the Chinese ingenuity is without limits and very often also without any practical limits :-D

Yes I have a feeling that this will work out very fine in the end.

The modification on the adapter might be something that Brad can use in his next batch as it is rather easy to do and might help many dealing with the freewheel/freehub removal.
That is however up to Brad to decide and evaluate the benefit vs. possible higher price in manufacturing cost.

Thank you everybody for the help and genius ideas that helps this project forward :-D

All the best :-D

01-25-2013, 04:02 AM
The loccating lips were drawn as "squares" because it gives you something to measure! Very hard to machine cones to an exact size, as it is hard to determine a start / finish point with domestic equipment! Alsdo, the cone would leave a sharp edge, rather than a nice neat edge from the "Square". With close maching and 'Square lips, the whole case can be assembled, and a light cut taken right accross the outside, bringing it to finish size, and almost hiding the joins between the plates. Also, you need as much contact area between the plates as you can get, and it is possible to finish up with the faces of the cones acting as contact, which is not the best.
With the dowel pin between thre axles, there really is no need for the bushes here. I used the ball bearing idea because I have seen it before, and it is dead simple, but all you need is a loose fitting pin, and brass washer betweent the ends of the axles, just incase the finish up rubbing, The pin holds the washer in place. In fact, this way is better, as there is less chance of the washer falling out!
Still working on dimensioned drawings--had to finish a clock case deign first (money wins sometimes)
Steve G

01-25-2013, 04:46 AM
Hi Ticktock :-D

I agree that the square solution is easier, it's probably just my gear head custom gene that made me draw them with cones.
Kind of mostly for the challenge it gives :-D I might very well just use your design instead when all comes to an end.

Yes the dowel pins will work as guides too :-D.
I was actually planning to machine the outer rings so they fitted within a 1/10th of a mm to the freewheel adapter housing.
That and the center pin would by all means take care of most of the centering issue.

Yeap a build and test driving etc and the a trip to the lathe for the final finish cut/polish and the unit should look sooooo neat.
If we make all the outer parts in aluminium and polish the unit afterwards together with SS bolts, nuts and washer it would almost be a pity to paint the little ***** :-D
Or worse if we make it in aluminium and get it anodized in a neat red, black or shiny blue or whatever we like then I'll have to hang on on the wall and 1 on the bike ;-D
I have to investigate where I can get parts anodized in Denmark.

Wow or black painted steel ends with red anodized center rings 8-0
***** I haven't even build it yet and I'm all over the place.
I think a high gloss black Timber Wolf with red anodized spoke nipples and red anodized center rings and some red pin striping done.
Yes I think that might be groovy :-D

He-he, this is really going somewhere I think.

Thank you for your help, and don't worry, make your normal life work and do this only when time and mood permits to work on this little project.
OK I can't help much from out here and I can't benefit from you work before I get home to my parts.
I'm sure that there are Zombies out there who are really anticipating your finished work :-D

All the best and good luck with your projects on work as in free time :-D

01-26-2013, 10:58 AM
I have nearly finished dimensioned drawings for the diff, when I realised that a word of warning is needed!!!
If you fit this to any of the AZ trikes, the location of the inner bearing arms must be altered to suit the diff. Biggest departure from the plans would be on the Load Runner 1 and 2, as there would have to be two inner arms instead of one center arm. In all cases, no big deal, and fairly obvious.
The sneaky bit is that on Deltawolf, Deltarunner, Timberwolf and Auroa, etc, there must be a small change to the way the rear cross member is attached to the main boom, in order to give clearance over the diff casing. So if you want to fit this diff to any of these, don;t build the rear end until you know whats needed.!
Now, my printer has died, and the scanner is on holiday , along with the rest of China---does any one know how I can post here, or email, a Deltacad File so that anyone can open it? At present, I have the files in Deltacad format, but you would need Deltacad to open them.
If you get the answer to this, you can all have drawings in a couple of days!!@!!
Steve G,
PS, Neville, the long pin between the axles may not work, as the locking bolt for one adaptor wants to use the same space! (or close enough to cause a structural problem)

01-26-2013, 12:07 PM
Hi Ticktock :-D
Got a point there with the pin, but there are several ways around this.

Here I have changed the design for the axle ends:

I have a few sketches for rear swinger of the coming Timber Wolf for myself.
There are endless possibilities here, but this is what have been in play for now.
This is however just for playing as I want to build my hub before I build the rear, so the sketches are only mind games from my side :-D


With respect to your printer problem.
In fear of giving stupid advice's, have you tried to use the "Save as" command and check for the possibility to save as JPG or other recognized format?
I must say that I haven't ever used the Delta CAD program so I'm just trying a little, sorry if this is already tried.
I often use "Irfanview" as it reads sooooo many formats especially with the full plugin package installed.
It might be worth a try, and once opened this program can save as JPG format.

All the best :-D

01-26-2013, 07:24 PM
Hi Neville,
You see the problem correctly. The two sketches wth an "A" frame are likely to create another problem by fouling the top chain run with suspension movement, especially in top gear. the asymetrilcal and the build over will work. The assymetrical is lighter by one support arm. Even easier is to simply extend the rear boom by 40mm, and weld it on top of the cross beam, then cap the hole in the end!.
Because the locking bolt is quite close to the end of the axle on the RHS, I would be reluctant to drill any holes into the end of that axle, but the left side is OK . So I suggest a brass washer with a short "axle" that fits in the end of the LHS axle. It is only there to remove any side play between the axles, and to prevent them hitting. load should be zero, and revs very slow and very few! But it needs to be there.
I will try more ideas with Deltacad later--family says I have to go out now!
Steve G

01-26-2013, 10:30 PM
Ticktock, I don't know what operating system you are using but this program "CutePDF" works with windows. It acts as a printer and saves the file as a pdf file. It is free which I like. I used it to save pretty much everything on my laptop when I wasn't connected to a printer

here is a link to the download page http://cutepdf.com/Products/CutePDF/writer.asp

01-27-2013, 10:20 AM
Thanks everyone, but I think I have solved the posting problem--Deltacad does allow transfer of JPG, so if I' right, you get some pics in two seconds!
I should have said it uses two 18 tooth freewheels!
Details of the spacers will come in the next thrilling instalment, when I get time.
The only critical dimensions are those for the bearings, and the locating lips around the edges. Accurate indexing of the bolts will help!
Please check and tell me of any errors or ommissions etc, as this was done quickly.
Have fun,
Steve G,

01-27-2013, 10:25 AM
It seems that the dimensions are not too clear on my screen anyway. Tell me if this is the case, as I see no way of enlarging what is posted.
I can repost again, but enlarging the dimensioned parts of the drawing--the rest is pretty obvious any way once you get the general idea.
Steve G

01-27-2013, 12:01 PM
Hi Ticktock :-D
Yes the dimensions aren't that clear but I think this is a limitation in the forum that creates this issue which is understandable.

I like your design, and during a quick look through this looks fine :-D
I would trim the left side axle end to fit into the other axle with a bush and a washer as on the latest sketch to make the axle ends links so the connection will contribute to minimize the pedaling force deflection even more.
This is however most likely overkill and not needed in the real world.

I'm soooo looking forward to see your work in the real reality :-D

If you would be so kind, could you send me the drawings in a much better resolution on my personal e-mail.
I can be contacted on penola@gmail.com
Then I can have a closer look at your drawings (mostly for my own sake)

Thank you for the help on this project :-D

01-27-2013, 12:45 PM
You have just given me an idea that may solve this lack of clarity! Deltacad did give me a choice of reolution, defaulted at 50/100, so I left alone. I will try again at 100 and see what happens, just for fun.
I don't think you will bend a 20mm axle over that distance--and any support given by a small dowelpin would depend on wear, which it would do if it had to take peddle strain, so with wear you would be back to no support, and hope the axle is strong enough on its own. I prefer to take away the problem, and not need the support in the first place, then it can't go wrong! If the axles were off center, the diff would still work as I have drawn it--with a joining dowel, then the axles may well bind up and cause heaps of problems--even if the holes were just a bit off this would happen.
So now lets see what happens --6075607660776078
Steve G
I knew I would find a use for the edit function one day---I tied at 100%--did not make any difference. I then found that if you click on the image again, you get it on its own page, and under the View tab is a choice of Zoom. But the numbers are still too hard to read.
Looks like the only way is to get the printer and scanner working--thats the next two days fighting with Microsoft!!!
Steve G

01-27-2013, 12:55 PM
One thing I would like to point out. Maybe you realize it maybe your so into it your did not realize it. Between Ticktock and Penola you guys look to be using 3 freewheels for this differential.
There is only need of one if your using a thread on Mega geared freewheel attached to the differential. The Mega gear is a freewheel in itself.
I believe the original idea was to have a single gear driving the 2 18 tooth freewheels and a mid-drive driving the differential. However with the Cassette mounted to the Axle and differential there would be no need of the third BMX freewheel. Not to burst your guys bubble. But it is something I just noticed.

01-27-2013, 01:52 PM

I think you are correct. If the cluster freewheel is pinned to the axle, that would eliminate one bearing, the center section, one freewheel adapter and freewheel. You just brought the time and cost down by at least 2/3 if machine time is included.

Great catch!

01-27-2013, 01:58 PM
Hi darnthedog :-D

I have been thinking a little about you idea, and maybe I just can't see over my nose here.
I think you are completely correct for a turn to the right.
I case of a turn to the left we get the same as a stiff axle.

Again I might be off my board here, but as you suggest I see a problem.
right turn:
Drive through the mega range to the right wheel which will drive the bike and the outer(left wheel can freely spin faster due to the left freewheel).

Left turn:
Drive through the mega range to the right wheel which will drive the wheel at chain speed.
The left wheel that should turn slower than the Right wheel isn't allowed to rotate slower than the outer wheel due to the lock function in the left freewheel.

In the design with 2 freewheel and 1 mega range freewhub the function is slightly different:
Right turn:
Drive through mega range to right freewheel and the left (outer) wheel can spin faster due to the left freewheel and the system makes turning easier.

Left turn:
Drive through mega range to left freewheel and the right (outer) wheel can spin faster due to the right freewheel and the system makes turning easier.

So your system will work for the anti spin function and the turn to the right, but turning to the left will create same function as a solid 1 piece axle.
present design will at all time let the outer wheel in a turn move faster, but never let any wheel spin slower than the chain speed dictates.

Hope that I have explained this correctly and I'm not totally blind because I've been so focused on this project for some time now.

Ticktock, please let this go through your mind as well and comment on this.
If we can save a freewheel it would be nice I just don't think it can be done with full function intact :-D

Thank your for chiming in on this darnthedog :-D

Tom Schneide
01-27-2013, 02:17 PM
You could eliminate the freewheel on the mega gear but you do need one on each axle. Each axle must be able go faster than the other for right or left turns. As Penola said, if pinned to 1 axle, the other axle could not go slower just faster.
You could put a cassette on with a suitable mount since you don't need a freewheel on the cassette.

01-27-2013, 02:38 PM
still need 4 bearings.. look at the rearend on any rear wheeldrive car or truck
with 3 bearing it leaves on side of an axle unsupported

as far as using one freewheel... tape two ratchets with extensions togather then try and turn both ratchets after that put a breaker bar on one side instead of 1 ratchet and try it again

01-27-2013, 03:07 PM
Actually your Mega Gear axle will always determine the speed as your peddling right or left turn as it is always driving both the axles altogether. The Mega Gear Axle will also freewheel so when going right or left the slower wheel will be allowed to go slower to reduce tire wear. Having 2 freewheels on same axle will not make it freewheel any easier. The idea for a differential for a bicycle is different then in an automobile. In a bicycle the differential is not require to make the bike go forward unless there is a slippery surfaces such as ice or sand in which you want both your wheel to be able to drive forward. Thus you only need one freewheel per axle the drive axle will always drive regardless of how many free wheels you use. Anyway sorry if this throws you off. Feel free to build it as you desire. Just trying to save you some parts.

01-27-2013, 06:32 PM
again.... look at the dif in a rear wheel drive car/truck... the ring and pinion gears spin at the same speeds but the speeds of the wheels change going into corners without this axles BREAK or tires spin.

you do not need a freewheel built into the gear cluster but being there is no adapter made to allow the use of a casset style gear cluster most of us builders may not have a choice but to use a 5/7 speed freewheel cluster unless an internal geared trike hub is used to supply the change of gearing headed to the dif

01-27-2013, 09:24 PM
Hi darnthedog :-D

You are not 100% correct I think.
Your system will work under most circumstances:
Turning right
as locking differential
freewheeling (no pedaling) in a left turn.

Not when pedaling in a left turn.

You say:
" The Mega Gear Axle will also freewheel so when going right or left the slower wheel will be allowed to go slower to reduce tire wear."

If you go left it isn't possible to freewheel the mega range AND drive the diff via the mega range at the same time.
It is not possible to drive the fastest wheel and let the slowest freewheel.

I am aware of the difference between this and a car differential :-D

Yes the only reason for using a freewheel hub in the gear cluster is that it is easier to fit for most of the builders here compared to the problems making a cassette adapter vs the thread for the freewheel hub cluster.

All the best :-D

01-27-2013, 09:43 PM
LOts of interesting discussion!
Comes down to this---the only freewheel we do not need is the one in the cassette hub, but you must have one there! Why?
Because , althogh the two differential freewheels do indeed act as a single freewheel when you stop peddling, or back peddle, the is far too much chance that there will be enough internal drag through the complete diff to affect the chain tensioning ability of the derailer.
The moment you back-peddle with a stiff freewheel, you derail the chain on the front cogs--trust me--I've done it accidentally by getting a chain guide tube dragging on a derailer.
So the easiest way is simplyto use the multispeed hub as is, as we know how to mount that easily.
If you did build without the third freewheel, you would be in trouble if anything went wrong insidr that little diff, as you could get instant fixed wheel, so the third free wheel is good insurance. Also, it will roll much more easily than using the internal freewheels.
You must use four pillow block bearings for the axles, as the only way you could use three would be a much more complicated build on the diff! It can be done, but this is a design to built at home--as far as possible anyway.
Anyone with access to a lathe that can spin 100mm+ should be able to make these parts. I have access to a 200mm lathe, and I have a 80mm lathe. With adaptors I can tuurn 125mm on this small lathe, and I intend to try to make this diff on the small lathe, just to check how easy it is to make on a small lathe. Won't be quick, but anyone with such a small lathe is usually not in bussiness!
It was correctly pointed out that this diff will work with just a single chain input, from , say, a midrive unit, or other multi gear hub . In this case, either a single speed freewheel can be fitted as usual, or a single sprocket bolted on to the casing (fixed drive at that point)
So long as there is a freewheel in the midrive or the hub, this will work OK. I would use a screw on adaptor to fit the single gear if possible.
It gets a bit difficult to bolt on any sprocket under 20 teeth--I have done it with 22.
So at this point, the design remains unchanged until either tested, or some major improvement can be made (or errors corrected)
Thanks Everyone,
Steve G,

01-28-2013, 12:04 AM
I can get bigger numbers on Deltacad!!! Lets see if it works--
Now I hit the send button and wait.'
Steve G

Can you all read that???? I can!

01-28-2013, 01:53 AM
Hi Ticktock :-D

Yes this is readable :-D
I will scrutinize the drawings a little :-D

All the best and thank you for the detailed drawings :-D
Really nice work :-D

01-28-2013, 05:38 AM
After a bit of mental assembling, I think that while there is nothing wrong with the set up as drawn, it is a bit too much of a watch making exercise as regards the location of the 7mm bolts---they have to be spot on exact in position, or it will not assemble at all!
The answer--well there are two answers! Both are easy. one is to change nothing and use 6mm bolts and holes. the other is to use 7mm bolts and increase the PCD from 70 to 73mm . 7mm bolts are the better size to use, so it is better to increase the PCD.
It is just too close for a home build as drawn. One of the problems with CAD--if it fits it says its OK, but a human has to make the bits.
So this is the first design change!
Steve G

More research, forget the 6mm bolt idea--better to increase the PCD to give more clearances inside the case. There is almost no gain with 6mm bolts.

03-05-2013, 05:13 PM
Am I correct in thinking that this device is the same as Samagaga's "Easy Turn Gear" (http://www.samagaga.com/Category.aspx?Category=ETG) ?

03-05-2013, 05:45 PM
Am I correct in thinking that this device is the same as Samagaga's "Easy Turn Gear" (http://www.samagaga.com/Category.aspx?Category=ETG) ?

Same idea different methodology. This is using free wheels to simulate a differential.

03-05-2013, 10:23 PM
Hi Bambuko,
AS far as I can tell from the Samagaga site (they supply no internal details) their "diff" cannot be a freewheeling diff, as they provide a mount for a disc brake on the diff casing. This would be totally useless on a true freewheeling diff, If the easy turn diff is a geared"normal" car type in ternally, than it is pretty much useless for us! As they quite correctly state on the FAQ sheet, a wheel in the air will just spin and you go nowhere (their words!) Same will happen on any loose surface. What we want is a limited slip diff, and thats kinda pricey , if you can find one to fit.
The freewheel diff allows cornering by allowing the outside wheel to tun faster, leaving the inside wheel to drive through a corner.
But if thatwheel tries to spin, the diff locks, and drive is transferred to the outside wheel. (in fact, both wheels)
So you get two wheel drive when you need it, and the ability to turn. And it can be made using mostly standard bike parts and AZ adaptors.
All we did was to refine the concept, and put it into a pretty case!
I will stress the point again--a normal diff is useless to us--its worse than no diff at all!
Hope that helps,
Steve G

03-06-2013, 05:15 AM
Have a look at this video (http://www.youtube.com/watch?v=M0dK6hB4fUg)

It looks like double freewheel contraption.
BTW Samagaga do both differential (http://www.samagaga.com/Category.aspx?Category=DG72) and easy turn gear (http://www.samagaga.com/Category.aspx?Category=ETG) (ie double freewheel thingy)

Of course, you could always buy British (http://pedal-trikes.blogspot.co.uk/2010_09_01_archive.html) https://lh3.googleusercontent.com/-qnijrvWaBXs/R7IjTBiQMhI/AAAAAAAAEPQ/YJqATWApqls/s800/flag_British.gif :punk:

03-06-2013, 07:01 AM
Hi Bambuko,
The Samagaga diff does not appear to be a free-weeling diff, as they provide a mount for a disc brake on the casing. If it is a "normal " diff it is useless to us. If it turns out to be a freewheeling diff, don't use the disc brake mount without carefull checking first.
I suspect it is a form of cam lock, as used on some auto LSDs . Could see any price guides on their site.
The UK made unit really is a free wheel diff (prefer your name of "double freewheel thingy" as it stops calling it a diff--it is not ! It does not divide torque.
It looks well made and designed. It is exactly the same in principle as the unit we have come up with for home building. it is smaller, and probably lighter, but at the price you would expect some advantages. Main advantage of our "thingy" is that you can get spare parts at the local bike shop, or even the hardware store, and you don't need to get special axles made at a machine shop if you use AZ adaptors.
Hope to start on a prototype soon, so I will keep you all posted as it proceeds.
Steve G
(Before ordering one of the UK models, best to check out compatability with the hubs you intend to use, and include this in any price comparisons you are making)

03-06-2013, 08:23 AM
... Samagaga diff does not appear to be a free-weeling diff, ...
Indeed it is not, and that's the whole point - until recently they only offered the diff, now they also offer "easy turn gear" which appears to be exactly double freewheel device.
Please forget about Samagaga diff and look at "easy turn gear" :rolleyes4:

I am looking forward to seeing your device, when it is ready :scooter:

03-06-2013, 08:40 AM
I was carefull to say that I do not know what is inside the ETG! Logically, it CANNOT be a freewheeling diff, as they would not be so silly as to mount a disc brake onto the casing! It would have the same stopping power as a stationary set of peddles==zero.
Your mention of the ETG is first I have seen or heard of it, so it is quite new.
If it can use a disc brake on the casing, and it does lock axles on wheel spin, it becomes an interesting proposition, but I imagine, a pricey one.
Personally, I would still use discs mounted on the axle, so that I still have brakes in the event of ETG explosions ! The brake on a casing would be illegal on a car in most counties, with good reasons.
Pity that nothing on Samagaga site tells us what it really does, and at what price. Add on special axles and it could get quite pricey.
If I was in the UK, the UK model is not a bad buy, but it is too expensive here in China--would cost me more than the whole bike here!
Steve G,

03-06-2013, 09:08 AM
I have just had another look at the Sammagaga ETG. The test report they give shows that they have only really tested it to about 280 Kg chain tension. At the back of a mid geared trike this is not even half the force most of us could apply in a low gear!
Also, the test method proves that it is not a freewheeling thingy! If it was, all the stress would be applied to the chain, and nothing to the fixed axle. Result would almost certainly be a destroyed casing, as, given the some what flimsy mounting in the machine chuck, and the lack of any center supports near the diff, I see casing failure as the only result. If it is some form of locking diff, then the chain is only there for show, as the axles should lock- and thats what they appear to do. So logic says it is not a freewheeling diff.
I have some doubts about the usefulness of the test or its results.
Bike chain is rated at a max stress of well over one ton, just form the record. Using their test set up, and driving the diff by the chain, but with two fixed axles, it would almost certainly self destruct before a speed chain breaks.
Might try to get more info from them if I get time tomorrow.
Steve G,

03-07-2013, 08:49 AM
Hi All,
I did phone Samagaga this morning. Got a few surprises. One was good English. Two , was intelligent answers, and three was the price.
Against all my arguements, it really is a freewheeling diff (double freewheel thingy to use the common name)
Jerry, who I spoke to had no hesitation in describing how it works and what it does (and does not do).
It is essentially the same as our design, and that from the UK, but I think the ratchet system is different, but the result is the same.
I asked about the disc brake mount, and he confirmed that a disc brake would not work in that location. The mounting was intended for a second sprocket for electric power. he went on to say a parking brake could be fitted there, but could not understand why it would not work (except backwards).
Then I asked the price, and asked him to repeat it in Chinese to confirm---32USD . Now I think he has misread something, but we will see later.
I then asked about axles and hubs, and he stopped me and asked for an email giving some details.
So we are now waiting for the reply.
As to the price, I had been talking about the disc brake model so as to get a better answer as to what it did, but in reality, most of us would probably want the Casette hub version, which is what I asked about in the email.
If he is correct at 32USD, its a good price, even if you get custom axles made locally.
I think it was Socialtalker who got some axles splined just recently. Dare we ask the cost?
This is starting to look interesting. Hope they will supply one unit at a time, and not expect orders for five thousand.
I will let you know when I know.
Steve G,

03-07-2013, 09:42 AM
At that price (assuming it's correct) - it would cost me more to get materials, not to mention my (theoretically free) time.
Delighted that my guess as to what it is turned out to be correct.

03-07-2013, 10:27 AM
Hi Again,
I just ecieved then email from Jerry at Samagaga.
He gave me a list of parts that would normally be needed for one trike. Remember that they think in terms of uprights and delivery trikes,
in my opinnion, some of the bits are not much use.
Lets start with the parts list and prices as quoted--

Plain ETG unit USD 32
Cassette ETG USD 42
Axles (2) USD 32
Axle adaptors(2) USD13
FD Hubs (2) USD22

This makes for a total of USD 109 for a Casstte model, and USD 99 for the basic unit.
THenyou add postage, for me, Taiwan to Beijing, USD46. So if I used the Cassette model, bought all tghe recomemnded bits, with postage, I would pay USD155 .

I have had a good look through their drawings etc, and come to the conlusion that the hubs are not really suitable for what we expect out of our trikes (pity, as they are an easy fit) The flange width is ony 48mm--the same as the dished front wheel on my LWB. A far cry from the 75 or 80 mm flange width on my trike . If you did use them it would have to be with much care, and on only 2o inch rims or smaller And that is not a recomendation as to suitability. The other objection is that the axles have to be reduced to 12mm to use the adaptors so the weakest point is right where you need the most strength.
So I plan to get an ETG cassette model, along with 2 axles. Its cheaper to buy their axles than it is to mhave them machined here in China!
I will use about three or four inchs of their axle, and join it to a 20mm axle as normally used (youn guys in USA read as 3/4")
Then I can use normal AZ hubs. The inner 20mm pillow blocks can have a collar fitted to hold the smaller axle.
I will have to modify the rear of the old trike for this to happen, but its only a matter of moving one axle support, I think!?!? I sense Murphy in the background.
I think, without actually measuring, it will be possible to use my existing axles and wheels.
Now you know everything except your own personal postage costs!
Any questions, ask me or email webmaster@samagaga.com and mark "atten Jerry"as he helped me a lot.
Payment can be by Paypal.
Steve G
If a few of you in one location got together, you could save a bundle on postage by making one big order.

03-07-2013, 11:16 AM
Hi Ticktock

That sounds dirt cheap :-)
I still think I'll give a homemade version a try just for the challenge and fun building it :-)
Ok the torque you mentioned is also a little low for me I think :-)

Thanks for the information :-)

03-07-2013, 11:46 AM
Thats exactly what I thought about the test torque. Sounds a lot- but not when you know what it means. Their whole test is open to question in my oppinion, as it does not seem to be "real life"simulation.
Now we have confirmed that it really is a double freewheel thingy (to stop calling it a diff), I can't see what they were trying to test!
It appears they stuck one axle end in a torque "generator", and the other appears to be locked to the test bed.
The chain is a fixed chain to stop the thingy casing from turning. So now we know what happens inside , we can predict what will happen when torque is applied to the end of the axle. If the axle is driven "forward", nothing happens, as the freewheel on that axle will just let it turn. No load on anything at all. So it must be turned in "reverse" to apply any load. Then the driven axle freewheel will lock, and attept to turn the casing, just as a bike pushed bacwards turns the peddles backwards. As the chain is fixed, this will put the chain in tension on one side, and apply a huge bending stress to the axle, which is only supported at the extreme ends .The casing will not turn any further than the chain and the bending allows, untill the axle breaks. The other axle is under no torque load at all at this time, as its freewheel cannot lock!
So in fact, I am bit surprised that the whole axle did survive this rather crude treatment. It does not relate in any way to normal use,
and just leads me to ignore the test results, and make sure that my axle is properly supported close to the thingy.
At the price, its not worth while trying to make one, unless theirs proves faulty later.The bits I need will cost me about 120USD, and about a days work. Might be a bit more if I have to build new hubs. And I may be able to use an 11tooth sprocket if I really go mad! Joking, won't change the gearing-its works too well as it is.
To make one at home will cost me close to 50USD if I'm lucky, and two or three days machining bits on a small lathe.
The whole confusion for me was caused by the idea of fitting a disc brake to the casing!! I did suggest that they might like to change the wording before someone does not stop!
Steve G

03-07-2013, 02:58 PM
I wish you were closer and I had 2 of these.
As A long suffering member of I.N.T.A.A.(I Never Throw Anything Away)
It's the true diff. out of my first riding lawnmower. 26 1/2" long, 3/4" axles with 3" key-way on each end. As it sits it 10.4 pounds Take off the 9" dia. 1/4" thick sproket I'm guessing weight would be under 9 pounds.


03-07-2013, 08:25 PM
Hi Trikedoc
When I first started thinking of a trike, all my training was telling me that one wheel drive was not safe etc etc, so I was looking for a proper diff, and this type of thing came to mind, despite the weight. I have since learnt from experience that a normal diff is a waste of time on a LWB trike, and one wheel works fine 99.9%of the time for normal use. A normal car type diff is worse than no diff in our usage.
The double freewheeling thingy is the only economic answer for what we need. If Samagaga's thingy is any good, they will sell heaps of these, as they are supplying what is needed. Just hope it is made well enough to last a while. I feel the UK version mentioned on this thread is better quality, but the price is too high for most people, and if that were the only thingy on the market, I would make my own.
The "low" torque on their test is a bit of a worry, as I can generate twice that in my low gears (getting close to maximum on the chain by that time), but as they don't aim for trikes with a mid drive and 9GI gearing, it is understanadable. Their figures represent a 200lb person standing on a 170 crank with a 22 tooth cog on the front. Thats the worst normal case they can think of. Maybe they will need to bring out a heavy duty version later, but until WE try to break it, they won't know. I am surprised the casing did not fail on their test, so thats a good start!
Just ran a few numbers though the calulator, and my normal riding only gets to about about half of their test torque! Its only if I drop onto the small cog on the front that I can start to get up to , and over their numbers, so it may not be such a big problem in the end.

Have fun,
Steve G

03-07-2013, 08:50 PM
Hi Trikedoc

A normal car type diff is worse than no diff in our usage.

Have fun,
Steve G

I gather your referring to on a normal diff. if you spin one wheel you lose forward motion. Yes but your likely hood of spin out is greatly reduced because your power is being applied to both rear wheels with double the traction.


03-07-2013, 08:51 PM
...The "low" torque on their test is a bit of a worry...
It would only be a worry if the test failed at this low figure - as it is, it doesn't prove anything. It simply states that when tested with this torque, it didn't fail, but doesn't tell us what would happen if the torque was higher?
More than likely, the value chosen for the test torque is driven (pardon the pun) by some "standard" ...

03-07-2013, 08:59 PM
But with one wheel drive you can lean a bit of weight onto the drive wheel, and nearly achieve the same traction as fixed two wheel drive.
With a normal diff, this will result in even less drive, as the maximum push you can get comes from the slipping wheel, which can then slip more easily, and thus give less push.
Believe me, once any wheel can spin, a true diff is useless! Even a 200hp tractor goes nowhere when one wheel spins.(except down)
Steve G.

03-07-2013, 09:10 PM
Hi Bambuko,
Yes ,I think there is a standard they used. As I said earlier, that torque is about the same as a 200lb person standing on 170crank with a 22 tooth sprocket.. A logical test figure to start with, but a total fail figure would convey more security to most users.
Lets hope the total fail figure is not 201 Ibs!
Time will tell,
Steve G

03-07-2013, 10:15 PM
I imagine that Samagaga's "Diff" has been well tested on the Greenspeed Anura and Utah Trike's custom delta and quads...

03-07-2013, 10:47 PM
I imagine that Samagaga's "Diff" has been well tested on the Greenspeed Anura and Utah Trike's custom delta and quads...


With bearing support in close to the diff. it looks like it could take anything a peddler could dish out.

03-08-2013, 12:33 AM
Hi Trikedoc (still nervous--I checked again)
True that Samagaga diffs have been tested on these other trikes, but we are not talking about the diff in your picture! That is a diff.
We are talking about a "double free wheel thingy", which Samagaga call ETG. This is a new product, and we know nothing about it except the somewhat dubious test report. If the ETG is set the same as in the photo, which is what should be done, we will nebver bend an axle by peddling, even at 16mm dia.
Their test does give the impression that the casing is OK, so the only unknown is how well the internals will stand up to our abuse. This is where a total fail test would give some idea where we stand, but I can understand their reluctance to include this information at this stage.
I have taken the plunge ten minutes ago, and ordered my bits from Samagaga, one ETG Cassette version, and two axles.
I will keep you informed as to what happens next.
There was no problem with ordering just one unit, except the postage is a bit pricey!
Steve G

03-08-2013, 02:50 AM
Utah Trikes uses them on their custom Catrike quad (http://www.utahtrikes.com/uploads/utrecenttrikepics/3265/pic/10.jpg)

The rest of the pics of this beast can be found here: http://www.utahtrikes.com/RECENTTRIKE-The_Ultimate_Quad.html

03-08-2013, 07:47 AM
But with one wheel drive you can lean a bit of weight onto the drive wheel, and nearly achieve the same traction as fixed two wheel drive.
With a normal diff, this will result in even less drive, as the maximum push you can get comes from the slipping wheel, which can then slip more easily, and thus give less push.
Believe me, once any wheel can spin, a true diff is useless! Even a 200hp tractor goes nowhere when one wheel spins.(except down)
Steve G.
this is why tractors have seperate brakes for each rear wheel if that wheel starts to spin you tap the brake
and the power goes to the other wheel thats not spinning

03-08-2013, 10:21 AM
That was the old days---now you just hit the diff lock button! The individual brakes are only used for steering.
Steve G

03-08-2013, 10:45 AM
Hi Tradetek,
That looks like the disc brake model (using their description) with a wiiiide spacer for the sprocket. I have seen this quad before, but missed the ETG part-. Its a good recomendation, so I feel a bit safer with my decision to buy one and see what happens.
Now the news update on that subject is that Samagaga were real quick of the mark, I got the Paypal invoice, an order confirmation, and an advice that all parts are in stock , within one hour of emailing the order. It was paid for ten minutes later, and payment acknowledged when I checked an hour later, with a possible delivery on Monday. Thats pretty good. I don't expect it on Monday as I have had too many dealings with express couriours here! Can't blame Samagaga for the couriors stuff ups.
Thats a pretty mean looking quad-- I kept our Husky away from the sceen so she does not start making demands about the morning walk!
It certainly sets a high standard, but I suppose given enough time and enough cash, any thing is possible.
Steve G

03-08-2013, 01:37 PM
Ticktock, so I guess you saw the pic on the main photos page with the quad hooked up to 4 sled dogs then!

And I don't know about you, but I do know that the "unlimited funds" issue is why I'm here! :rolleyes4:

03-08-2013, 02:03 PM
Ticktock, so I guess you saw the pic on the main photos page with the quad hooked up to 4 sled dogs then!

And I don't know about you, but I do know that the "unlimited funds" issue is why I'm here! :rolleyes4:

I don't know about you and Ticktock but that quad would have NO pedals,gears, spiffy diffy thingy, motors,batteries, controller, chain.crankset just needs a 10' pole with a rabbit tied to one end.:wheelchair:

03-08-2013, 02:19 PM
That was the old days---now you just hit the diff lock button! The individual brakes are only used for steering.
Steve G

For some of use it still is the old days. sniff

03-08-2013, 02:57 PM
Yes, when I saw this beast the first time hooked up to a couple of dogs it made me want to go out get a couple Husky pups. Ours passed away last year and she was as strong as an ox!

03-08-2013, 08:35 PM
Don't worry, when you make clocks it's the old days every day.
Nothing wrong with that beastie--at least it does not have a computer, and you can see everything that makes it work!
And fix it when don't want to work.
A freind has a new" John something" tractor with 48 gears and more buttons then a Jumbo jet, and the brakes totally stop working when the motor stops---now which one would you rather drive around a hill? I rather like the old days.
Steve G

03-08-2013, 08:44 PM
Hi Trike doc (got it right first go this time)
I have just redesigned the next build. Should cause a stir here. no gears, no diff, ,just rear wheel brakes. Have placed an order for four harness, and three more dogs. Also ordered four sets of boots for the dogs, and a long pole with a fake rabbit on the end. I did have one with a carrot, but after testing last night, decided the acceleration is better with the rabbit.
You have just saved a lot of money, and got the dog to loose weight all in one go.
Now I'm of to buy more dog food with the money I saved!
Steve G

03-08-2013, 08:54 PM
Hi Tradettek,
You are right,the Hushy is incredibly strong for their size, and love to pull. Even on a tiled floor, our little beast can , going backwards, drag me around the house on the office wheelie chair. and if she gets on a run outside she will drag you off your feet esasily. They seem to be able to keep the pull going evenat a run, which most dogs can't do. maybe they manasge to keep one foot pushing all the time, as thetre is no slack in the lead when she gets going.
Apparently, on a weight for weight basis, dogs (husky) are stronger than a horse. A horse is only happy pulling about twice its own weight, whereas (onlyheard this) a dog is OK with five times its own weight. Seems about right when you start adding up weights on a good dog team.
There is a site somewhere for dog carts , scooters etc, which is where I picked up the tip for boots for the dogs.
Even my horses had their own rubber boots for any long road trips. Thedylove them once they get over the first attempts to kick them off.
Steve G

03-18-2013, 09:21 AM
Hi Guys,
Latest news. I picked up the Samagaga ETG today , from China Customs.
It was extreemly well packed, much bigger box than I expected for two axles and a thingie, al wrapped in bubblewrap'
All I've done so far is to open the box, and look! It looks good, looks well finished, and feels right so far. axles feel like they are good steel, and are well made. So far, impressed with their service and the product.
Next I will pull it apart and look inside, just to see whatmakes it click!
It is small, and light weight. No one should be concerned about the weight of this beastie if they need a diff of this type.
Steve G,

03-18-2013, 04:51 PM
I'd love to hear all the juicy details on this one Steve! I have been looking into something that their products would be good for.


03-18-2013, 05:20 PM
Hi Trike doc (got it right first go this time)
I have just redesigned the next build. Should cause a stir here. no gears, no diff, ,just rear wheel brakes. Have placed an order for four harness, and three more dogs. Also ordered four sets of boots for the dogs, and a long pole with a fake rabbit on the end. I did have one with a carrot, but after testing last night, decided the acceleration is better with the rabbit.
You have just saved a lot of money, and got the dog to loose weight all in one go.
Now I'm of to buy more dog food with the money I saved!
Steve G

Steve, We need someone willing to call UT an ask about buying one. I looked for just the Fat Larry's on the back $160. each. I'm thinking with the prices of there stock trikes
that purple thing goes for 5 figures!

03-18-2013, 08:54 PM
Love to see their faces when I ask for delivery to Beijing, and do they accept Chinese Yuan in Cash!!!

As a test related to Eds thread, that was a triple enter then.
If you are correct at 10k plus than it would cost about 60,000 Yuan, and our biggest note is a 100 yuan! Would be a nice bundle of cash.

Double enter-- How about a secret camers when I make te call?
Steve G,

07-05-2013, 12:44 PM
Hi all contributors,

I might be a little out of touch with this thread, but Steve G, how has the Samagaga ETG all worked out and what was the final spec out costs involved, have you got any pictures??


07-05-2013, 05:50 PM
Savarin and Steve G calling on your knowledge sirs.
What stops this working?

Each axle (half shaft) has a keyed end.
A tube 40mm ID with a gear/sprocket fixed in the centre to provide the drive.
Press fitted (vice pressed) into both ends of the tube a sprag clutch
http://simplybearings.co.uk/shop/Bearings-Sprag+Clutch+Bearings/c3_4585/p152504/CSK17+17mm+Sprag+Clutch+One+Way+Bearing+Without+Ke yways+17x40x12mm/product_info.html
Then fit a key to the end of each half shaft to connect the whole lot together

Isn't this a bit more garage hacker and closer to the origins of this thread.

Let me and the 13,196 other followers of this thread know if this could work.

07-05-2013, 09:25 PM
Hi Tim,
Sounds like it would work, provided that clutch is a freewheel ratchet type, and they fitted right way round. but a press fit is not reliable when transmitting driving torque--anything you can vice press will slip in low gear--been there , done that! Lucky it was on a tandem, and the stokers drive still worked, or it would have been a long walk home!
Even easier is the earlier idea that started the whole discussion on diffs, is in an earlier thread, where the center tube has six studs welded to it, engaging in the teeth of BMX sprockets each side, which fit on to freewheel adaptors. No need for a keyed shaft.
Hope some one can point you in the right direction for this thread. (might have been Saverin, but not sure)
If you can overcome the slip problem, its a neat solution, especially if you can keyways done on the cheap.
Steve G
Just got a quick look at the clutch--it is shown with no keyway for the shaft, and the specs only mention a press fit on the shaft. may be a bit difficult for a Zombie to handle four press fits in one go, with axles and wheels waving in the air. Chances are that a BMX sprocket is cheaper than the clutch, and easier to find.'

07-06-2013, 03:19 AM
Hi Steve
thanks for getting back so soon.
Thanks for the first hand experience of why vice press would not work, really important bit of detail that.
I have come across CSK20PP 20mm Sprag Clutch One Way Bearing with Internal & External Keyways 20x47x14mm, so this has the key on outer ring also, this could work then?
The bmx sprocket design is the one I made and now use, but I am trying to improve on this as it looks a bit crude (possibly my making skills are part of the problem) and you can still see the tell tale freewheels on each shaft - I am looking to create an engineered looking solution on the cheap.
If the only thing now standing in the way is a couple of keys then this should be ok to overcome.
Let me know what you are thinking Steve and others.


07-06-2013, 07:18 AM
After I left home this morning I had a feeling it was you that designed that diff!
As DIY "diff", its as good as they come--you can't do better without machining, special bits, and spending money. My solution would be to tidy up the construction a bit, and use what you have already developed, while we copy!
Now, the clutch with internal external keyways will work, but at quite a cost in machining!--I prefer the money in my pocket, and tolerate the home made look.

Seriously, looking at it another way, by the time you get four keyways cut, buy two clutches, buy another sprocket as driver and weld that, its going to be cheaper to buy a Samagaga ETG and two axles, fitted with a cassette, and drive straight from the cranks or mid drive. --and that does look professional. But if it breaks, start pushing, as you won't buy one from the corner shop.
Your first plan is the winner with me, as its made from stuff you can get almost anywhere, and should give plenty of visual warning of impending failure.

Back to the question--with four keyways it will work very well, should be quiet, and should last . Just be careful with axle alignment and support, and retaining.
Steve G

07-06-2013, 08:12 AM

Savarin posted the original design.
Yes I have made a version similar to the original design, hopefully simplifying it a bit, by using a conveyor roller as the two pieces of tube that are welded inside to just the sprocket of a disassembled single speed freewheel. To achieve the drive to both freewheels mounted via Brads design of freewheel adapter I welded some short m6 threaded to the outside of the tubes, it is probably this part I do not like the most.
It is fitted to my delta trike
Your thoughts on improving what I have are similar to what I was getting to in my own mind, so that is my first option, replace / smooth out the m6 studs and perhaps cover the freewheels that they attach to.
Watch this space, however here in the Uk we are having some really nice weather this weekend, so the work will not be started for a few days most likely.
It would be interesting to know how many people want to make one of these units, because I can make some drawings for others to follow if required, or maybe with sufficient interest Brad adds it to his list of parts to buy in the shop !

07-06-2013, 08:37 AM
Well, M6 can be replaced with 6mm Rod, and look better, maybe painting it all black, but there's nothing wrong with something that you made from nothing, and it works!
Same as my LWB---it don't look as good as most of the racers in this city, but its fun when you beat them anyway!
Your concept here is about as good as you can get, with improvements as I noted--use rod instead of M6 and (we all want to be able to do this) just tidy up the welding.
If it works its good--if it ain't broke, don't fix it!
If you think for a moment, the only part needed in kit would be the center tube and sprocket--the rest is optional to the builder. And of course, when the pins do eventually wear out, and the teeth disappear from the sprocket, a new one is needed, it sounds like a good business.
Now if we take the simple idea and find a way to add a cassette/ freewheel directly, and eliminate the jackshaft, that really is a win.
I designed one that does this, but it does need a lot of lathe work.
Interesting if you have had any quotes for the keyways, as I feel this will be the stopping point.
Steve G

07-06-2013, 10:25 AM
With reference to the key way
This was done using a Dremel type hobby drill thing for the shaft, could some of this be done using a grinding disc ?
The one for the inner join tube might be more difficult, but could you not just drill a hole for a dowel, or put on a thread?

07-07-2013, 08:21 AM
How about this for an idea


One machined part with bearings fitted.
Shafts then just require keys cutting into them
Item supplied with keys

Any one interested ?

Cannot see why it would not work

Allows for freewheel to be fitted to the end, as per any adapters sold in AZ shop

Works like any other adapter, but has the benefit of two wheel drive

07-07-2013, 09:21 AM
You are 90% there with this one!
You will need a couple more parts to make it fool proof and wear proof!
First, the press fit bearings are not reliable to drive, so the external key way feature must be used. Good point here is that it only needs to be one (but two is better) dowel pressed into the shell, to locate each bearing . To be able to put in two bearings, one after the other, these dowels must be accurately placed. Then it would be wise to add and end cover, to close off the shell.
The other thing the assembler will love you for is to add a spacer between the outer races of the bearings, so the second one can't go in too far .
The bend cover is just a plain disc with ,say, four small bolts into the end face of the main shell.
Be very careful with axle alignments, and keep the inner bearings as close as you can to the whole thing, allowing for rear cogs and chain.
Neat design --like its the next step up from the one I drew some time ago--but I had the goal to use standard bike parts wherever possible, while making a sealed unit.
Al we need now is a tutorial on hand cutting a key way-----it can be done. In fact, that's the way it was done a few years ago--hammer and chisel!
Steve G

To help explain why you will need the external key. Its not being over cautious.
On the Tandem, I used a twin thread rear hub that I can buy here. In the past, I tried to use one of these to make an adaptor, so I took one apart . Normayl, I separate the two ends from the center, and bash out the bearing cups, as they are too hard to file or machine. This leaves a mild steel hub center with thread, which can be machined , or filed, to suit the axle.
This new hub was a bit different, and had the thread cut on a pressed metal "cap" which was then used to lock the center of the hub over the bearing cup, Therse were all press fits.
They were so tight I could not separate them with normal hammer and vice work. I could not even tell how they went together at first--the parts really were tight . I had to destroy the thing in steps to find out how it was put together, and only at the last minute did it all fall apart . Bad news was that the threaded bit cant be used without making an adaptor for the the adaptor!
'So whats the problem-sounds like they should be ok for a bit of torque?
I used the twin thread version for a mid drive on the tandem, and partly forgot, partly false sense of security, did not weld the hubs to the center.
Well , this new hub was much stronger than the old style--they only get to the end of the drive way before they slip if not welded. The new style lasted about four days, then slipped.
That was a press fit far tighter than any bearing specification.
Its now been welded, and I hope everyone will now heed Brads advice to weld the centers of a mid drive!!!
Hope that means more than just saying it won't work!

07-07-2013, 05:14 PM
Version 2

The parts list is:
1. Body (estimated cost 40)
2. Cover washer ( estimated cost 5)
3. Sprag Bearing CSK20PP with internal and external key ways (cost 16.12 each 2 off required)
4. Dowel pins 3mm (2 off estimated cost 2 for both) - might even consider allowing for 2 per bearing as only 3mm
5. Internal circlip INT0480 ( estimated cost 2)
6. Bearing tube (estimated cost 2)
Total estimated cost 85.24 or approx $138 us - is the feasible or realistic ?
Might even suggest adding the cost of laser etch "AZ Freehub"

Oh and the cost of the keys

Cutting the keys see post 117 for a link, also noticed my grinding cut off disc is 1.15mm thick, how hard can it be then to create a 6mm wide key.


07-08-2013, 05:53 PM
Love this "differential" thread.
What an inventive bunch AZ folks are :-)
My thinking on an approach to this was probably naive in the extreme so I shall be watching this with interest!!


07-08-2013, 09:33 PM
That works form me . See no problems with that, but don't have a press fit on axle and the body- or you will never get it apart, let alone the battle to get it lined up for assembly!
Just think of a Deltarunner rear end-two 26 inch wheels, on axles, trying to get into that diff--a bit wobbly!
Good one,

Now the comparisons start,
Samagaga ETG-- for either screw on or cassette----USD 32 (here you can use 11/34 megarange if you use a cassette hub)
Samagaga axles two 32
postage guess only 50

Total 112 and you only need to weld two axles. Here your way wins as it is hard to get the axles true, your way they are true !
But then you can't say you made, and that's priceless!
Have fun with this--it will work.
Steve G

07-09-2013, 05:39 AM
I guess it is "damn-fool"-question time, and as I fit that description quite well and ignoring the old adage that says if you suspect people think you are an ***** don't open your mouth and confirm it for them...... ;-)

I like the elegance and simplicity of the design but I wonder about the keys ability to stand up to the stresses that may be imposed on them.
Assuming the axle is still only mild-steel and is not treated or case-hardened in any way will it (or any attached/affixed key) be up to the loads imposed?
Clearly the bearing are made for just this type of application so it is to be assumed that they can take the loads, but what about the axles?

I know nothing (clearly) about metallurgy and/or sheer strengths etc. and I have no clear idea what 9.4kn is (648 ft-lbs?) and whether this sort of stress will ever exist in the drive-train.
I assume not as the weight of a rider of c.(200-250lbs) standing on a c.1ft crank sounds to me like 250 ft-lbs in the drive system somewhere (now there's a real guesstimate for you) and if all of that was transmitted to a tiny mild-steel shim of metal in a slot in a similarly mild-steel axle would it hold fast ok with no issues or eventually chew its way free?

Hoots of derision may begin immediately......3.....2....1....GO!


07-09-2013, 10:47 AM
It is not a dumb question!!! It is, in my opinion , the weak link in the system, and you just prompted me to do some real number work, as I can see its a close call.

So lets look at worst case, normal use.
Rider 250 lbs
Cranks 170mm
Front cog22 teeth, ==11"circ /pi=3.5" dia =45mm radius.
Rear cog 34 teeth=17" circ/pi= 5.41 dia=68mm radius
axle 10mm radius
Torque is not a factor here, it is shear stress at the keyway that counts. don't worry about using lbs and millimetres--the millimetres cancel and the answer is in lbs, just the same as if you use inches.
So we have 250 lb rider standing on a 170 frank, with a 22 tooth front cog pulling the chain
Stress on chain is 250X170/45=944 lbs ---nearly half a ton!!
this force acts on the rear sprocket and keyway
So the shear load on the keyway is
944X68/10= 6420 lbs that's roughly three tons!
Maximum shear stress in mild steel is 21,600 psi (lbs/sq. inch)
so minimum shear area of key must be 6420/21600= 0.297 sq inches or 192 sq.mm.
Bearing is 14m wide, and this stress can be applied to one wheel only at any time. So key must be 192/14=13.7mm wide! Not possible.
So on first look it won't work.
Now lets bring some reality into the picture! In my opinion it is extremely unlikiy that any one will use this much force in low gear on a bent.
This torque would produce about 280lbs thrust at the wheel--almost enough to climb a brick wall if you could get traction.
But in top gear a strong rider may do this often--so lets see if its any better--
Front crank is now 42 tooth, and 6.68 "dia=84mm radius

Rear cog is 14 tooth and 2.22 dia=28.29 radius.
same rider
Stress on chain is 250X170/84=505 lbs .
transferred to back end
505X28.29/10=1428 lbs on the key ,
so key way now would need to be 1428/21600=.066 square inchs or43 squ.mm With 14mm bearing width, this means a key with a width of 3.07 . This would double if you were restricted to the big cog up front, but used a 28 on the back, which means 6mm key is about the smallest you could use, and then at considerable risk of shear failure in lower gears.
So, unless anyone can show me where I'm wrong, it will be a close call.
See Dan--it was not a dumb question.
I'm a bit surprised at just how big the key has to be--but not surprised at the stresses generated. The only way to better this would be to try a high grade key, but as its in a mild steel axle, I would not even bother to try.
So, to keep a good idea afloat, somebody find fault with the figures. Its easy to get bogged down on a wrong track, but I don't think I have .
Steve G
I have not checked if the two dowels would be ok, but I doubt it after this surprise!
Steve G

Just done more checking, and the ultimate strength of mild steel is around 50,000 psi , but no engineer would design on that figure. If you took the gamble, it would halve the widths I have calculated, but double the chance of failure.
I.m done checking--somebody tell please tell me I'm wrong !!

07-09-2013, 01:28 PM
maybe a feasible idea to achieve a differential type rear drive?
Just thinking out loud.
The hub with welded spoke flanges was posted on AZ somewhere but ?? The freewheel adapters must be attached to the shafts in same direction.

http://i992.photobucket.com/albums/af44/MrDEB/differential_zps6bb6852a.png (http://s992.photobucket.com/user/MrDEB/media/differential_zps6bb6852a.png.html)

07-09-2013, 02:31 PM
Thanks Steve,
I am relieved to find that I am possibly not quite as barking mad as might be thought and that perhaps my fear for the design has some merit.
At least the saving grace for a recumbent is that one is unlikely to have something snap while standing on a pedal and have one's gonads crushed by 200+ ft/lbs of falling un-suspended body and an immovable and intractable cross-bar...OUCH!! ;-)



07-09-2013, 05:01 PM
Worth checking the maths, easy solution is put the key in the 47mm bore the entire length then this takes out the need for the dowels and makes the alignment of the bearings easy.

Steve does this bearing work for the loads?
There maybe a bit more of a garage hackers approach to using sprag bearing if the maths are ok.

07-09-2013, 05:06 PM
Mr Idaho
If you look at post 16 of this thread you will see the version I made that works just fine, just not very pretty.
Next task is to make it pretty.
The sprag clutch idea is a theoretical can it work and can it be pretty and least possible machining as well as functionally capable.


07-09-2013, 05:52 PM
I failed to realize more posts.
Looking at post 21, I get lost as to what the description is stating.
post 16 looks like a finished working unit but an update on construction etc. might be helpful before I start melting metal.

07-09-2013, 06:12 PM
Mr Idaho

Look at post #115 and this is the unit fitted on my delta trike.
Simply follows the principle as stated right at the start of this topic by savarin.
Anyway all it consists of is a freewheel 18 teeth mounted on each axle shaft.
Joining the two axles is a tube with m6 drive dogs to lock into the freewheels. In the centre of tube (actually two tubes is a free wheel, but just the sprocket, welded on the inside, then the chain drives this.

It really works, just not very pretty, when you corner the drive goes to the inner wheel in the turn and the outer wheel just clicks.
There it is

If you have time, read all of this thread, it has been going for some time, the theme is as always what can we diy create, right up you street.

07-09-2013, 06:32 PM
I think this is where your plan is?
If I am correct then I must build--lol Now to locate some single bmX SPROCKETS or ? wonder if possible to cut down a full cassette? or something to thread onto the freewheel adapters. I have extra bearings and tubing w/ 2"ID
http://i992.photobucket.com/albums/af44/MrDEB/reardifferential_zps82d10aa1.png (http://s992.photobucket.com/user/MrDEB/media/reardifferential_zps82d10aa1.png.html)

07-09-2013, 06:53 PM
Mr Idaho
The tube is from a roller conveyor and the inside diameter is a nice snug fit on the flange of the bmx sprocket, being only about 1mm wall.
The tube was then cut into two pieces and a third free wheel was tacked apart, again another 18 tooth sprocket (centre sprocket)- the reason was I did not want more the 18 teeth is that it is driven via a jack shaft with another 18 teeth sprocket.
If the centre sprocket is bigger it reduces the gearing.

Your drawing is not wrong, just watch you do not end up with too big a gear and mess up your gearing, an easy solution is have the same number of teeth to the driving the centre sprocket.

Hope this makes sense

07-09-2013, 07:15 PM
Mr Idaho
Rubbish iPad drawing below hopefully makes my rumblings before clearer
Oh for neat handwriting and a decent free iPad app to draw with

Hope this helps


07-09-2013, 08:22 PM
Hi all
looks like a couple of points here, so all answers in one go,
The hub concept is really a development of the normal AZ hub designed by Brad, but I posted the drawings showing it used on the end of a kingpin, intended for the front of a tadpole.
Using a long jack shaft an short axles is not the cheapest way to go, as at least one extra pillow block has to be used to support the cassette on the jackshaft---remember that 800lb + strain on the chain? use a short jackshaft, with two bearings, and a normal AZ rear frame will be much stronger all round, and easier to make.
Good thing about a bent is that a chain break is just a loud bang and then stop--no screams of agony.
Good point about a freewheel diff is that you get two chances if a key does fail--but its not long before the next one goes!
The original idea is still the best, as its so easy to make, inspect, repair or replace, with normal bike bits. It passes the stress tests because there are six bolts working on a much greater radius--one bolt would probably pass there!
The new bearing is smaller, with a 12 mm axle, so it is likely, from past experience, no calculation needed, that the axle will fail!
If you have a similar drawing for the first bearing, showing key sizes and all those nasty numbers, it may help prove I goofed up somewhere, as even now I don't believe the keysizes I come up with I would have expected 6mm square key to do the job, as pointed out by Dan, wear being the big problem, leading to a failure in low gear.
If the max torque for this bearing is the 9.3Nm shown in the spec sheet, it won't survive!
As to full length key way in the "body"- great idea, functional for use and assembly, you won't break that one easily. But run the idea of a key way into a dead end past the machine shop first.
It can be done, but depends on their tooling as to how close to the dead end they can get!
If you look at the difference in key sizes on the bearing drawing, it will give you an idea as to how much more stress there is on the shaft key---they made it bigger.
If you use BMX freewheels on the original idea, they are really just plain single speed freewheels of a kids bike--18tooth is suggested sized as its most common, and allows a choice of 1, 2 , 3,4, 6, or 12 studs! 4 or 6 is best.
The bearings in the center would appear to be not needed based on first reports, but are a nice touch (but more machining?). There is no real need for the nuts to hold the sprockets--its all locked in by the axles.
Just keep the inner bearings close to the center.
Now I think that covers everything, in no particular order.
I will have another coffee, while you guys think up the next session!
Then I might get started on that seat 1
Steve G

07-10-2013, 06:54 AM

Knowing you are better at the maths involved than I, there are a few questions that come up from my experience in mechanical fields. I've installed bucket and belt grain elevators, and some of the stresses on the drive system make me wonder how it can work at all. Granted, we are working on a larger scale than the typical delta trike, but the principles should be the same.


This is from memory, it's been almost 20 years since I did this.

2' radius (4' dia) top and bottom wheels for the belt and buckets.
100' between 3" shafts
~210' 1/2" thick x 8" wide belt -- not sure total weight of belt and buckets, but I understand the upward moving side of belt weight is cancelled by downward moving side.
Total weight of grain being lifted in the buckets would be close to 2400 lbs. Guestimate, given how short a time it takes to empty a 5T load from a grain truck.
20 HP 3450 rpm drive motor has 10" dia. 2 sheave pulley, 1/2" key
Gearbox driven pulley is 36" dia. on 2" shaft, 20:1 reduction.
Gearbox output 2" shaft with 12" 4 sheave pulley.
Pulley on bucket belt 36" dia.
Hubs on all shafts are tapered compression type, with keys.
All keys are 1/2"

I know the compression hubs do account for a major part of the torque transfer, but still, how do those keys survive this kind of abuse?

By the maths you presented, those keys should have sheared the moment power was applied.

Believe me, installing the motor house on an 90' tower wasn't fun, especially for someone not comfortable with heights. Yes, I said 100' C-C on belt axles, pit was ~15' deep.

In automotive use, most accessory drives are friction fit to the accessories -- alternator, water pump, etc -- with the only keyed shaft being the crankshaft with 1/4" key. Wouldn't this be much higher torque than on a trike sprag clutch differential? Crank keys take a huge amount of shock load, with every firing of the each cylinder.

On these trikes we are talking much smaller scale, and the keys are taking essentially all of the torque transfer. I would bet the keys would survive the punishment.

07-10-2013, 07:22 AM
KEYways now were talking $$$ to have someone cut the keyways.
I read through the entire thread and still can't get what post 21 is drawing.
My idea was to use some 2.25OD 2" ID tubing to hold the bearings (these will keep everything straight I think?
Only addition would be adding a cassette in place of the center drive sprocket.
Use a freewheel adapters to hold the cassette in the middle but this needs to be locked to the tube. Thats where I need to do some thinking.
Going back and study post 21 again

07-10-2013, 07:32 AM
Hi Charlie,
I hope you forgive me, but I did not go through and check your figures, as they are too logical. As I said, I am surprised at what my quick check showed up, and would have expected a much smaller answer.
Why does your system survive? you gave half the anwser--tapered shafts locked tight is half of it, and the other half is the 1/2" key is probably 2or 3 inches long. Based on the numbers I used, that's at least one square inch shear area for the key, and that means it fails at 21600lbs nearly 10 tons! So with a 2inch radius pulley and ,say, one inch axle, that means the belt could lift 5 tons before the key sheared . Reasonable safety factor there, and confirms I'm not too far off line . The most torque will usually be at the end furthest away from the motor.
Most pulleys etc on motors are either press fit or taper, and also keyed. Actual torque is lowest at the motor end, usually, but the shock loads are higher. the press fit or taper must be the redeeming factor here.
I was not surprised at the chain loadings at all. If you saw the independent suspension rear end I drew up, I did say there was a surprising stress problem in the design---it was the chain loading--so I was already aware of the numbers for the chain. What surprised me was how quickly that force multiplied by the time it got to that skinny axle!
In normal use we don't use that much force, but a sharp jab in low gear would be enough to cause a problem based on what the numbers say.
If I read the chart properly the manufactures specs really make this a moot point, as it seems the torque limit on the clutch is far lower, which ,of course , explains why their keys survive.
And , for what its worth, I am still amazed by the numbers!
I would have built it with a 5 or 6 mm key and expected it to be OK, but the bearing/clutch does not accept this.
Steve G

07-10-2013, 08:26 AM
Maybe I missed something?
I looked at the drawing in post *21 again (I failed to realize that clicking on the pic it gets bigger-duh!)
Yes the freewheels are on backwards BUT will a 3/4" axle fin into a cassette ID?
I like the way the freewheel adapters are used, very compact.

07-10-2013, 08:44 AM
First, lets make sure we are using the same terminology- or we both get totally confused.
There are two types of multi speed hubs, and both get called cassettes. One of them is not a cassette!
One screws on to a "normal", bike freewheel threaded hub, and is usually called a free hub, thread on or screw on,
The other one is a cassette. It differs in that the cogs slide onto a splined hub, which contains the freewheel and bearings. They are easier to remove and can be custom built as each cog can be replaced. The bearing setup results in a stronger rear axle.
Gets confusing because when you look at a free hub you see splines on the inside! These are not for the cogs--they are for the tool to remove the whole thing from the hub!
So now we come back to your question--
A 20mm axle will pass through a free hub easily. However, in most cases, you are limited to a 14 tooth small cog. I have heard of smaller being available, but doubt they would accept a 20mm axle. 13 tooth might.
A 20m axle may pass though a cassette, but there is no way to mount it , and a 20mm axle will not pass though the cassette hub--no way!
Hope that helps without boreing you if you already knew most of it.
Steve G

07-10-2013, 11:34 AM
Hello Folks,

I think the freewheel "sourced" arrangement depicted by go1000go (TIm) and MrIdaho are right on the money because they use components specifically designed for the stresses induced by cycling to effect the differential slipping clutch requirement and the tube/tubes joining these two halves will be crush/twist proof.
Just a thought.......If you modified the inner ends of those 2 tubes to provide mating bolt pathways on common BCD pattern/centers then the center sprocket might be interchangeable/serviceable too and might offer a range of Sprocket-teeth options" perhaps?



07-10-2013, 12:34 PM
I am getting jazzed about this differential
QUESTION, I do not have a freewheel adapter in hand but the measurements in post #70 drive side end-plate are the dimensions of the freewheel adapter that AZ sells?
Plus it appears the housing is 3 separate sections? w/ aligning pins.
will make corrections as to freewheel sprocket adapter and not a cassette.

07-10-2013, 02:45 PM
Hi the MrIdaho, I think the answer you seek is on Sheldon Brown's site, but I do believe the threading for the freewheel's is compatible with the AZ adapter, see http://www.sheldonbrown.com/gloss_e-f.html#freewheel

British (http://www.sheldonbrown.com/gloss_bo-z.html#british)
1.370" x 24 tpi
34.80 x 1.058 mm

Sounds like a really good match with the AZ site info "The threads on the backside of the freewheel are fine 1.375" x 24 teeth per inch clockwise threads. These threads are standard on all Shimano type thread-on freewheels, even the single speed BMX types. Shimano freewheels can be purchased at most bicycle shops and are available with multiple chain rings ranging in count from as few as 5 to as many as 9. Department store bicycles and lower quality steel rear wheels are also a good source for salvaging a Shimano style thread-on freewheel." which is at http://atomiczombie.com/FDAX34%20Trike%20Axle%20FreeWheel%20Adapter.aspx

Go for it! :-)


07-10-2013, 10:20 PM
Hi Dan,
What you say is true, but its all too easy to get away from the dead simple, anyone can do it anywhere concept.
Even though I did the drawings for the fully enclosed version, it is not a good dIY project, as most do not have a lathe to make the bits, and commercial costs take the price way past whats already on the market.
So the first design is still the winner with me. As to wear on the sprockets--its so simple to make the center housing that I would just make another one when the sprocket wears out---by which time I may have forgotten why its there!
Steve G

07-10-2013, 10:24 PM
Just be carefull with Raleigh bikes in respect of freewheel and BB threads---they used a slightly different thread. and its almost impossible to tell the difference, except that they don't match, and will jam on.
I did start a thread with all these details a while ago, so its all on the forum somewhere!
Steve G,

John Lewis
07-11-2013, 12:25 AM
Just reading some of the recent posts.

When we look at the loading that may be applied to the keys and the like we need to keep in mind that the wheel will most likely slip long before those forces are achieved.

On my DeltaWolf the freewheel adapter and the brake adapters are "keyed" via a 1/4" setscrew that sits in a 1/8" deep hole on the axle. I actually have two at 90 degrees to take up any slack.
The thickness where the setscrews thread into the adapter is a little under 1/4".

Those fittings have survived several years of hard use with no sign of breaking.

I suspect that there is unlikely to be a problem with using the keys that were mentioned in previous posts.


07-11-2013, 08:45 AM
Hi John,
Thanks for a living example of this problem. You have two "keys" at 1/4 " diameter. (calculator died, so this is rough maths)which gives a shear area of about 56sq mm--which is more than the 43 I came up with on my "down to earth" calcs. Also, your two keys are probably not grade 1 or plain mild steel, so yes, I would expect yours to survive.
Also, remember that I used the "safe " strength of 26000psi, whereas the ultimate is around 50,000 psi.
But I think its all just a talking point, as I suspect we are working way past what the clutch can handle, if the spec sheet says what I think it says.
May well be worth an email to the suppliers asking for more detail in that regard.
Steve G

John Lewis
07-11-2013, 09:30 AM
Thanks for that information Ticktock.
It gives me more confidence. Not sure what grade setscrews are but certainly better than mild steel.
I still think the tyres would probably slip before the load became catastrophic.
I'm certainly no engineer so happy to be proven wrong.


07-11-2013, 10:37 AM
Hi again John. There is a limiting factor--it is wheel spin.
So I looked at what happens with our 250 lb rider sitting dead center between the rear wheels and forgot the weight of the trike--its all on the front wheel!
In low gear, the wheel will spin if force exceeds grip. Taking IG as the best grip, it means 125lb on that one wheel that's driving. What size key do we need to withstand wheel spin ?
250X125/10=3125lbs is the force on the key, which means we need 3125/21600=0.144sq. in. ==943sq.mm shear area , With a 14mm bearing, this means 6.7mm wide key.
So a key this size will allow things to work, but with care , as it assumes equeal weight on each rear wheel. If all the weight goes onto one wheel, the wheel grip doubles , and so does the max force that wheel can deliver, and the max possible load on the key doubles.
In top gear a 6mm key pass all tests--as the gears get lower it gets more critical.
So we then have to fall back on the fact that any high load is likely to be only short duration, and we can risk a lesser safety factor. Ultimate fail strength is nearly double what I first used, as is normal practice.
If you use the biggest key you can , around the 6mm mark, made from good steel, it will probably survive fair treatment for a long time. But use full power riding on one wheel in low gear and you stand a good chance of breaking the key.
All this assumes the clutch can deliver this amazing amount of power.
John, you are right--In low gear, with equeal weight on each wheel, it just spins before the key breaks. But with all the weight on the wheel, the key breaks --!
Interesting exercise, which I will avoid in the future--too many variables if you try to allow for everything . Would have been quicker to fit up a keyway and try to break it!
Steve G

07-12-2013, 12:35 AM
biggest force will come from braking not the 250watts or roughly 1/3 of a hp a human can produce
If a 1 inch long by 3/16 x 3/16 keyway is plenty to handle the forces of 5hp I do not think it will be
a problem and a bolt or setscrew is NOT a keyway

07-12-2013, 10:17 AM
Wrong--biggest force from braking can only related to tyre grip and no more, Guess what--its the same with the drive force--any more than the wheel can handle and it either spins or skids
Same thing either way. Difference is that normally you cant spin a bike wheel--but a trike in low gear and a strong rider may be able to get that much torque to the ground.
I can put the front wheel against a wall and spin the back wheel on mine!
But I can't if I move all the weight to the drive side. Lucky I don't have a keyed shaft, or I may have sheared a key or two. My low is much lower than the low I used in the earlier post!
But, even after checking the numbers, more than once, I am still surprised at what is needed, although its not much bigger than I would have used from experience , playing safe!
And don't forget, this has nothing to do with HP, Watts or even torque--its down to basics---shear stress at the key--not HP at the motor.
And if you read the drawings and the numbers, the key-way can only be , in effect, 14mm long--the width of the bearing--about half of what you correctly say is strong enough!
So I guess my calcs are not too far from the truth, allowing for the fact that I try to cover everything that could happen, and not just riding in top gear, when a rusty nail would work if you were gentle!
By the way, there is no comparison with the shear loads on the rear of a trike to the loads on the motor you show.
Steve G

07-12-2013, 12:14 PM
Further simplification of the design as per post #120
So here is the idea
Get this bored to 47mm inside diameter and get the key way cut into it
End plates do we bother with these ?

07-12-2013, 12:44 PM
As a suggestion and make it easier to follow this interesting thread, include a link to the post # that you are referring to http://forum.atomiczombie.com/showthread.php/5049-freewheel-differential?p=77738#post77738
It would make it easier than backtracking to find post #XXX
Just right click the post number you are referring to and copy link.
Now back to our program--
The sprocket pictured would require machining but I thought this thread was for a DIY differential that would not require expensive machining.
My thoughts leaden towards not using a sprocket but a plate that bolts to the housing. No sprocket required, just the freewheel adapter w/ a plate attached. HOW ??

07-12-2013, 04:49 PM
Mr Idaho
You are indeed correct that some 150 posts later we are in danger of losing one another.
Within this thread there are a few design alternatives being pursued, so here goes as a suggestion to make things clearer to all future contributors.

savarin original
Post 1 where this all started http://forum.atomiczombie.com/showthread.php/5049-freewheel-differential?p=48507#post48507

go1000go diy original
This is the version I have created http://forum.atomiczombie.com/showthread.php/5049-freewheel-differential?p=57701#post57701 now fitted to http://forum.atomiczombie.com/showthread.php/5049-freewheel-differential?p=77668#post77668 sketch of this unit shown badly in http://forum.atomiczombie.com/showthread.php/5049-freewheel-differential?p=77884#post77884

Penola design
This is http://forum.atomiczombie.com/showthread.php/5049-freewheel-differential?p=70128#post70128 Ticktock made a number of designs relating to this http://forum.atomiczombie.com/showthread.php/5049-freewheel-differential?p=70366#post70366

Sprag bearing
This is the design which excludes freewheels and was a proposed to give an engineered solution
http://forum.atomiczombie.com/showthread.php/5049-freewheel-differential?p=77738#post77738 This is where the debate on keys and key ways started.

I would like to thank Savarin for starting this thread and Ticktock for his many posts on the subject.

If this proposal makes sense then perhaps when discussing one of these four options we should identify which design we are referring to. Hopefully I have not missed out a design in this summary, but if I have please shout up.

07-12-2013, 09:33 PM
Guess you can't get much simpler than that one, even if it is not total DIY--but then only one of these designs is really DIY.
Suggest a brass shim washer between the "clutchs" and good lateral restraint on the axle, and very careful alignment.
What size is the shaft key on this bearing--can't see it mentioned or drawn anywhere.
Steve G

07-12-2013, 10:39 PM
Did I fall asleep or ?
What clutch?

07-13-2013, 12:26 AM
ok Ticktock I will bite.. so a motor has no affect
well Sir then Explain how much it muliplies when you have a 11 tooth clutch
to a 22 tooth gear on a jackshaft otherside of jackshaft is a 10 tooth to a 72tooth on a axle
this gives 14.40-1 gear reduction MANY TIMES more then pedaling alone with a 4hp motor Some gokarts use motors that make over 20hp and use KEYWAYS

07-13-2013, 03:31 AM
Mr idaho

sprag bearing
This design uses two bearings that are just like freewheels without the teeth, used in industrial installations that are often referred to then as a clutch, hence ticktocks reference to a clutch.

Steve G http://forum.atomiczombie.com/showthread.php/5049-freewheel-differential?p=78070#post78070 I think we know we are talking about the sprag design for using this sprocket, as the boss dia is 56mm my thoughts were that this would be ok with the 20mm bearing, od of these 47mm leaving 4.5mm thickness, however I appreciate the weakest part then is where the key way is cut, as this will create a weak point. The key for the od in the bearing is 3mm wide by 1.5mm deep, so guessing the same 1.5 mm depth of key in the bore, so effective wall just 3mm here.
If this is too thin then stay with the same 20mm I/d sprag bearing, as the next size down is 17mm which is too small I believe,
I think I am correct let me know....

So then if the wall is too thin then have too go up on sprocket size, 19 teeth boss outside dia 60mm should be enough.
The suggestion of a brass shim washer between the two bearings I concur.

No Mr Idaho, you have me thinking, yes I agree the use of this sprocket is not diy, I do not have a lathe. Yes the idea was to use this design for the sprag design , however (and this is why I like this forum) in our confusion over communicating clearly I thought you were asking how can this be used in savarin original and why the expensive maching. Bingo there we have it. This sprocket type could be drilled out to provide clearance, they come with a 12mm pilot bore, so progressively drill this out, I can do this without a lathe. To combine the sprocket and spacers and bolts to the savarin original design. Just measured my freewheels and the dimension to the root of the teeth is 56mm, therefore I could mount a series of 6mm rod on the boss, just do a neater job, something I am now considering as at 4.20 this is cheap and only requires a bit of effort.

It is good to discuss.

With the go1000go diy original I just used two tubes and crudely welde the drive lugs (posh term form some bits of m6 thread) however with this design I think I could create a good result.

My thoughts are always on low cost, easy elegant solutions using industry standard parts that can be easily modified with simple tools, just so you all are aware of where I am coming form on these designs

07-13-2013, 03:48 AM
I can do this without a lathe. To combine the sprocket and spacers and bolts to the savarin original design. Just measured my freewheels and the dimension to the root of the teeth is 56mm, therefore I could mount a series of 6mm rod on the boss, just do a neater job, something I am now considering as at 4.20 this is cheap and only requires a bit of effort.

No I can't just realised the reason I used a tube is because the bore needs to clear the adapter, sorry for any confusion Mr Idaho.

07-13-2013, 06:51 AM
Am considering building a differential but do not have the freewheel adapters so whild looking over the plans for the Viking transmission I see a freewheel adapter cut from a hub.
After I straighten up my work area I am going to do an autopsy on a hub and see what makes this freewheel tick. Maybe build a differential using the salvaged hub bits and pieces. Don't mean to sound so cheap but can't afford 3 x $26 for freewheel adapters. Come September maybe yes. but in the meantime its all DIY with what I have on hand.

07-13-2013, 09:33 AM
The limiting factor is nothing to do with horse power--it is SHEAR STRESS at the KEY WAY--does not matter how this is developed--one cyclist or an army of ants. or a drag racing engine.
If you exceed the key way stress, it breaks. The saving grace factor in all this is tyre grip. exceed that and a wheel either skids or spins, and usually that happens before the key breaks, especially with small wheeled go -karts. I realiased that there are so many variables in this, and it is such a close call if you rely on engineering numbers, its better to fall back on experience that says --this will work and this will fail--no numbers, as I can prove on one hand that a 7mm is OK, then change the conditions to the other , unlikely extreme , and it will fail.
A 1cc model aircraft engine could shear these keys if the gearing was right-- nothing has to move--its just stress at the keyway.
Steve G

07-14-2013, 05:05 AM
there is only one way stronger then a full length keyway and that is a splined shaft

at times waiting till have the funds available to buy the right parts is the only option as it will affect the quality of the final build

If you weld stuff to axles there really is no way to change it without buying new axles and making more stuff

07-14-2013, 07:18 AM
Am considering building a differential but do not have the freewheel adapters so whild looking over the plans for the Viking transmission I see a freewheel adapter cut from a hub.
After I straighten up my work area I am going to do an autopsy on a hub and see what makes this freewheel tick. Maybe build a differential using the salvaged hub bits and pieces. Don't mean to sound so cheap but can't afford 3 x $26 for freewheel adapters. Come September maybe yes. but in the meantime its all DIY with what I have on hand.

You can barely see the adapter type I made here.

http://i1094.photobucket.com/albums/i459/bcgeorge/bike%20pictures/th_P1010638.jpg (http://s1094.photobucket.com/user/bcgeorge/media/bike%20pictures/P1010638.jpg.html)

Old press together rear hub with a short length of tubing welded to it, pinned to the jackshaft.

07-14-2013, 08:15 AM
Steve G

07-14-2013, 08:21 AM
Yes, even welded axle parts can be changed with careful use of a grinder. However, there is one caveat -- noting outside the outer bearing on a delta should be messed with -- you've all seen the results in my threads.

07-14-2013, 05:46 PM
Yes, even welded axle parts can be changed with careful use of a grinder. However, there is one caveat -- noting outside the outer bearing on a delta should be messed with -- you've all seen the results in my threads.

use of parts and axle shafts with keyways and setscrews makes it a mute point and does not weaken the axle by drilling 1/4 holes in it repeatedly

John Lewis
07-15-2013, 05:02 AM
I made my adapters up . You don't need a rear hub as you can use one of the cups from an old bottom bracket. There were pictures on my Wolf build but that's all gone now. I have a home made lathe but you don't need one to do this. BB cups are hard but a grinder does the trick to mod them.

Here are a couple of shots . First is the cup and the second is the finished fitting.

http://i254.photobucket.com/albums/hh98/lew2au/fitting.jpg (http://s254.photobucket.com/user/lew2au/media/fitting.jpg.html)

http://i254.photobucket.com/albums/hh98/lew2au/Adapter.jpg (http://s254.photobucket.com/user/lew2au/media/Adapter.jpg.html)

Hope that's of some use


07-15-2013, 05:15 AM
How did you get the 20mm or 3/4 inch hole ?
Steve G

John Lewis
07-16-2013, 12:23 AM
Hi Steve G,

In the cup, because it is hard, I used a Dremel grinder. It took a while.
I turned up the other section and drilled it in the lathe.
The easy way is to get a collar the right size and use that.
As I didn't have one I chose to make it. Some thick pipe with the right ID would do as well.
I think it would be in order to just weld the cup to the axle but that makes it a bit permanent
and a problem if you need to replace the bearings.


07-16-2013, 08:08 AM
I am contemplating just taking a freewheel hub from a junk bike rear hub, welding a collar to be able to secure to a 3/4 axle.
Don't think I have seen a BB with a thread as John Lewis picture shows?

John Lewis
07-17-2013, 12:29 AM
You are right.
I must be getting old or something.

That one is in fact part of a free wheel hub.
It was another where I used the BB cup.

The threads are the same on both the BB cup and the freewheel so either can be used.
Just need to make sure you use the one with the right hand thread.


07-17-2013, 12:47 AM
Be careful with that last statement... BB's actually come in a couple of different sizes and thread spacings...

07-17-2013, 06:52 AM
Add to that--not all BBs, or freewheels, are the same thread. In USA , you will probably only see Raliegh as a different thread, but there are a couple of others to watch out for.
Raliegh is the same diameter as "normal" thread, but is 26 tpi instead of 24!! You need careful use of a thread gaugeb to pick that one!
Steve G

07-17-2013, 12:20 PM

older style 3 peice bottom bracket... yep threaded cup

07-17-2013, 01:14 PM
Top pic is standard crank replacement in China, using Bash in cups--bottom is normal theaded BB--can't tell if its English, French, or Swiss, or Ralliegh, in the pic.(But probably English as threads appear to be LH and RH ) As to the sleeve --no idea.
Steve G

08-20-2013, 03:32 PM
Hey Steve G

For another project, I ended up with one of these the other dayhttp://s10.postimg.org/l7c2cm9rd/image.jpg

It is a 21.9mm bore so a shaft will run clear through it.

So right back to post #1 where all this started ...

How about one on these on the left shaft, tube fitted to it that has the other end of the tube fixed to the biggest cog of the freewheel fitted to the right shaft freewheel (fitted so the gear still able to be used, ie. weld it). Derailer to change gears , driven by another jack shaft with Derailer and we should be able to get that amazing gear inch range on 20 inch wheels.


Will it work

PS one of these = the inner bit of a freewheel without the cogs on it from a 5 speed.

08-21-2013, 05:52 AM
Hi Tim,
That was a long trip back into history!
One thing here--you have just found another source of free wheel adaptors--we can now use AZ, machine shop, home made, cut down rear hub, left hand BB cup, or "one of these"
from a multi speed hub. Do't throw away the worn out hubs.
'Im sorry, I am having trouble visualising what you mean here. Can you do a quick sketch?
I have a idea from this description that may be what you mean, and it could work, but it would be hard to assemble, and almost impossible to dis-assemble!
Steve G

08-21-2013, 01:45 PM
Hi Steve G


The grub screw could be a number of fitting into some of the notches that are for fitting the gears to.
Haven't thought it all through but just thinking .....

08-21-2013, 10:39 PM
I think this was discussed before way back but the end of the 5 speed cog set would need a bushing for the axle to go through and bearings or bushings on the end of each axle as it may want to flop around.

08-22-2013, 11:50 AM
Hi Tim,
Just to make sure , before I say the wrong thing! This "thingy" is the freewheel part of a tread on hub????
If so, answer for Mr Idaho is that it has its own bearings, so no need to add further complication!
Answer for Tim--if it is the freewheel, it will work, but there are problems with assembly, and bigger problems with disassembly!
I have no use full suggestion as to how you fix the left side of the tube to the "thingy" --theres not much for screws, and it may be too hard to tap any way.
A suggestion does follow at the end!
care would be needed to avoid distortion of the big sprocket, and to maintain alignment of the tube, but it can be done. The axle and adaptor can be threaded into the right side, whether weld or bolted to the axle. But that's where the problems start--you will have major problems disassembling it to replace parts. A new sprocket means a remake. And with a welded adaptor you can't get the axle out, as a hub remover will not work the the axle in place. If its bolted, then you will have to drill holes in the tube to remove the bolt! Then how do you hold the adaptor deep inside the tube?
Suppose if it is a for a new sprocket you just cut the tube off to gain accsess, but for anything else its a problem.
Now we have got that far, and found that it looks like its a real pain to disassemble, here's the suggestion I warned you about! Its semi serious,
Just make the whole thing a throwaway, and weld the tube to the thingy, and make a new unit when the sprockets wear out. It will work that way!
And you can use the remains of the old hub to get a new thingy for the new one! Caution here though--I would be worried about that much heat going into the thingy, knowing that full of grease and ball bearings.
Quite honestly, when you can get a Samamgag ETG and two axles for around $100 , I wonder if it is worth it--I would rather use the ETG--its small, light, well made, and easy to set up.
Steve G

Steve G