Electric Street Fox? [Archive] - Atomic Zombie™ Extreme Machines Builder's Forum

Locutus

10-17-2008, 07:27 PM

Okay, so after seeing the new Greenspeed Glyde velomobile (hot d@mn!) I'm reconsidering building an electric Delta Runner. I may want to build a Street Fox instead. I think that building a shell for the the Street Fox similar to that of the Glyde would be a way cool way to go. The problem is though, where to mount a battery pack on a Street Fox. The DR has plenty of room behind and under the seat. But the SF is much more compact, and I think mounting paniers for batteries on both sides of the rear wheel may adversely alter the center of gravity towards the rear, whereas for safer handling I would prefer the CG to be further forward.

Once again, my quest is to make my 21-mile each way commute in less than one hour. So I have come up with what I'll call my 30/30 rule. That is, I want to build it so that I can go 30 MPH for 30 miles on a single charge without pedalling. This is my electric range/speed minimum requirement. I'll need to also carry the charger and extension cord on board as well, since I'll need to recharge at work. Of course I'll actually also be pedalling, but I still want that all-electric range and speed.

I'm thinking that something like that 1000 W, 48 V rear hub motor system with a 26" or larger rear wheel would be well suited to the task. I calculated that top speed would be over 30 mph with this setup. But again, where to mount the batteries. Perhaps I could build the frame to ride an inch or two higher and mount them under the seat?

Questions for Brad:
1. What about using batteries similar to those in the Cycle Bully? I haven't bought plans for that but looking at the pictures it looks like four smallish 12 volt batteries. That would give me the 48 volts but for range I might need to run two sets of four in parallel.
2. Do you think eight of these might fit under the seat of the Street Fox? This would be ideal because it would keep the CG low and not move it backward.
3. Would eight of these be enough to give me the range and speed I require?
4. What kind of batteries are they anyway?
5. In cornering, is there any difference in lateral force applied to the front wheels of a tadpole trike compared to the rear wheel? It seems to me that the front wheels might have a larger lateral load applied in cornering than the rear. I'll feel safer putting a 26" or larger rear wheel on the trike if this is so.
6. Will a rear wheel that has a hub motor installed be able to absorb more or less lateral force than a regular rear wheel?
7. Would you recommend different batteries for the Street Fox than those used on the Cycle Bully?

Anyone else that can provide some insights on these questions feel free to chip in.

AtomicZombie

10-17-2008, 08:38 PM

I would think that the DeltaRunner design would be much better for what you are after.

Brad

Locutus

10-17-2008, 09:17 PM

I would think that the DeltaRunner design would be much better for what you are after.

Brad

Even if I plan to enclose it in a full fairing shell? Most of the velomobiles I've seen are tadpole design.

TheKid

10-17-2008, 10:13 PM

The BionX hub motor is a good one for tadpoles, if you want to spend that much. I've seen the battery pack mounted on the main boom, between the seat and the pedals, or in back of the seat. In the gallery link below, notice one of the tadpoles has a suspension rear. If you can find a less expensive motor that can be used with suspension rears, it's not too hard to build a battery rack between the seat and the rear wheel. I made a rack for carrying stuff on mine, which could easily be modded to hold batteries.

http://www.bionx.ca/en/main/gallery/53.shtml

http://i192.photobucket.com/albums/z66/edpol_photos/Fox%20Rack/000_0442Small.jpg

Locutus

11-03-2008, 03:20 PM

Can both front and rear wheelsets from a BMX bike somehow be used for the two front wheels of the Street Fox? If so, what special modifications (if any) would need to be done to the rear wheel from the BMX bike in order to be used as one of the front Street Fox wheels?

TheKid

11-03-2008, 05:10 PM

As long as the axles are heavy, like 14mm, there's no problem at all. The front wheels on my Fox in the pic I posted in this thread are both rear BMX wheels. I used the freewheel threads to screw on disc brake adapters, which ddin't work out. Rather than install caliper brakes, I opted to use SA drum hubs instead. If you use a front and rear wheel, the freewheel side of the hub should go to the outside, so both wheels are the same distance from the spindle.

Locutus

11-03-2008, 05:18 PM

I opted to use SA drum hubs instead.

Thanks for the feedback, Kid. How did you like the drum brakes? Would you recommend them over disc brakes?

TheKid

11-03-2008, 08:48 PM

I have no real preference as far as perfomance, but I do think the drums look better. There seems to be a little less drag with the drums. I notice no difference in stopping power, even on wet roads. Cost wise, they cost me $50 because I was lucky enough to find a deal, and they were already set up for a tadpole, with left and right backing plates. Without the left and right backing plates, there's a little bit of modding involved. I've seen the SA drum hubs for $43 each plus shipping.
The cheapest disc hubs I've seen so far are the Bitex with 12mm bearings, the same size as the drum hubs. Two would cost $40 including shipping, plus the cost of the discs and calipers. So if you could get discs for $10 each and calipers for $15 each, plus shipping, the total cost is about $100. For either, you still have to add the cost of spokes, because it would be very difficult to find the right length from donors, and the cost of rims if you don't get them from donors.

Locutus

11-10-2008, 07:48 PM

Well, I decided I'm definitely going to build a Street Fox as the platform for my electric assist commuter trike. I'm going with the Phoenix Racer hub motor and a set of four EVP20-12B1 batteries in a 48 volt system, which can be seen here:

http://www.electricrider.com/crystalyte/index.htm

Two problems I'm encountering so far:

1. I'm having trouble finding a suitable swing arm for the rear suspension. Used bikes are getting pricey and I'd rather have new parts anyway. Wally World, Target, Sears, etc. bikes are incredibly cheap garbage. I need better quality than I can find there, since I'm going to be using the trike as my regular commuter, travelling at least 42 miles every work day. It needs to be reliable. On the other hand, good bikes are too expensive to buy the whole bike for a swing arm, but I can't seem to find just swing arms for sale.

2. The Phoenix hub motor is incompatible with disk braking, according to the FAQs at Electric Rider. Apparently the motor is too wide to fit in the frame with disc brakes. I'd rather have disc brakes, but perhaps I can get away with a good caliper brake on the rear and discs on the front two wheels. But I may run into a bit of a Catch 22: The better quality swing arms I've seen have disc brakes. Perhaps I need to fabricate a custom swingarm that can accomodate a longer axle so that a disc brake will fit? But I don't know if I can switch out the motor's standard axle.

Another area of concern is the total rider/vehicle weight. I'm about 200 pounds, so with me plus trike, plus 60 pounds of batteries, 27 pounds of hub motor, 8 pounds for controller, and various other hardware, I'm looking at a total exceeding 350 pounds. Later I plan to add a full fairing and paniers for carrying stuff, so I could easily max out at over 400 pounds. I'm concerned about the front axles, 16 gauge frame and steering system. I'm not sure they can handle this load, especially that I'll be consistently exceeding 30 MPH. Thoughts on this?

SirJoey

11-10-2008, 08:18 PM

Another area of concern is the total rider/vehicle weight. I'm about 200 pounds, so with me plus trike, plus 60 pounds of batteries, 27 pounds of hub motor, 8 pounds for controller, and various other hardware, I'm looking at a total exceeding 350 pounds. Later I plan to add a full fairing and paniers for carrying stuff, so I could easily max out at over 400 pounds. I'm concerned about the front axles, 16 gauge frame and steering system. I'm not sure they can handle this load, especially that I'll be consistently exceeding 30 MPH. Thoughts on this?

Welcome to MY world! I'm building the CycleBully from He**!
Battery weight: 150 lbs.
Motor weight: 20 lbs.
Estimated controller, cargo tub & trailer weight: 30 lbs.
Total: 200 lbs!

My weight: 175 lbs.
Estimated KC weight: 85 lbs.

Grand total (estimate) 460 lbs!!!

Altogether, with any cargo at all, I'll be flirtin' with the 1/4 ton mark, easy! :eek:
But then again, I'm not carrying all the weight on the vehicle itself...

http://img356.imageshack.us/img356/2839/thanksgivingsigsmalllu5.jpg

Radical Brad

11-10-2008, 10:41 PM

Joey - best to be going with the dual spring suspension for your machine.

Brad

Locutus

11-11-2008, 04:58 PM

Radical Brad

11-11-2008, 06:16 PM

Locutus

11-11-2008, 07:18 PM

I know this is probably not the answer you wanted, but for your target application, I would say the DeltaRunner would be the better choice of vehicle to start with. Reasons....

- No worry about braking as the motor is on the front so you get dual rear discs.

- Easy to find strong steel front forks or make your own 3tree setup.

- Much simpler to design a fairing.

- Add suspension to the seat, then the rest of the machine does not need it.

I generally do not recommend rear hubmotors for the same reasons you have described.

Brad

Yes, I've gone back and forth on this myself. When the Delta Runner design was released I thought that would be the way to go. But in looking into how the drivetrain would work, I decided against it because only one rear wheel would have drive traction, in the absence of a differential. With the tadpole that's not a problem because there's only one rear wheel. The batteries I've chosen will tuck nicely under the Street Fox seat and should give me enough range if I recharge at work. Cornering and drive wheel traction will be better in the tadpole. I can make a teardrop shaped fairing with the tadpole, which is better aerodynamically (see the California Commuter). The Street Fox looks like it will be lighter and more compact. Finally, there's the coolness factor. The Street Fox looks like one "sick" chopper.

If I can't find a suitable swing arm, I may build it without suspension and try to suspend the seat somehow. I'm also thinking that running the boom on top of a single piece cross beam might be stronger than the way the plans have it with a two-piece cross beam on top of the boom. I'll probably use a thicker wall tubing and 20 mm front axles as well. I think the weakest point structurally is likely to be the front axles unless I overbuild them.

TheKid

11-12-2008, 11:22 AM

I'm also thinking that running the boom on top of a single piece cross beam might be stronger than the way the plans have it with a two-piece cross beam on top of the boom.

The angled crossmember is one of the great aspects of the design. It allows placement of the front wheels far enough in front of the seat to get proper weight distribution, and a longer wheelbase for a more comfortable ride, without your legs hitting the crossmember. As far as strength, cut the crossmember as one piece, then cut a wedge out of the center and bend it to the "boomerang" shape. The back will still be solid, and all you have to do is weld the top and inside seams. I made mine that way, and it's plenty strong.

Locutus

11-12-2008, 12:15 PM

Good idea Kid. Thanks for the tip. What say you to putting the boom on top of the cross beam?

TheKid

11-12-2008, 04:02 PM

Actually, I wish hadn't done that. As Brad explains, having the crossmember over the boom allows for easier chain routing. It wasn't an issue when I had the mid drive, but now that the chain goes from front to rear in one shot, finding a good location for the return idler is a problem. I raised my seat due to disabilities, but if I kept it at the lower height, location of the power side idler would be a problem as well. Bear in mind, I'm using an internal gear hub with a 19 tooth cog. If I switch to a cassette, the problem with the power side idler will be present. I'd advise keeping the crossmember on top of the boom, as the plans suggest. If you look at the threads on the old forum, you'll see that Brad took a lot into account while building the Streetfox. I was building a tadpole at the time he started, and after many mods, went with Brad's method of building the crossmember. I put it under the boom, thinking that with the eventual internal gear hub, along with the mid drive, it would be a better location. I was right, but now the mid drive is gone to make fabricating a fairing easier, and the crossmember is kinda in the way. I may have to lower the steering linkage to make more room. But rather than spend time on it, I need a fairing more than a second working trike, so I'm devoting my time to a fairing for the DR instead of the Fox. At least when I get to the Fox fairing, the wheelwells will already have been made.

Locutus

11-12-2008, 04:36 PM

All good points, Kid. My two main concerns here are ground clearance for batteries mounted under the seat, and structural strength for the added weight of batteries and an eventual fairing. I think the ground clearance will be okay with the batteries I've selected. Perhaps I'll add some gussets to improve strength.

trikeman

11-12-2008, 05:06 PM

I find better quality components on some of the bikes I find at the thrift store, and they are cheaper than the ones at Walmart. I have started buying their more expensive ones (about $40) and most have only been ridden a few miles. The lower priced thrift store bikes are often good for the frames, but the components often leave a lot to be desired. I got a nice Trek (got that one for $6) last year, a good quality Schwins MTB with suspension, and a Specialized Rock Hard this year with a brand new Terry X leather saddle. I flipped the trek, since I couldn't bear to cut it up. All good quality components on them. People don't like to pay $40 for a bike at the thrift, so I usually have a better chance at getting one. The Schwinn has a good swing arm, great linear brakes, a mega range rear end new tires etc and will probably feel the hacksaw soon.

You can also make your own swing arm. It ain't rocket science, and you will most likely build a better one than you can buy, if that is your wish. Here is a guy that makes all of his swing arms from simple steel and a few bushings from the hardware store or some salvaged bottom brackets.

http://www.fleettrikes.com/john%20wife%20trike%201.jpg

http://www.fleettrikes.com/larry%20trike%202b.jpg

http://www.fleettrikes.com/luane%20after.jpg

Locutus

11-12-2008, 05:26 PM

Hey, I like the look of those. How do you suppose the pivot was fabricated?

trikeman

11-12-2008, 05:55 PM

Some look like bottom brackets. Others look like simple pieces of pipe with a bushing (either brass or nylon) with a bolt through them. Similar to the way he makes his king pins. Those who have tried the bolt and bushing method for king pins here report the salvaged head tubes work smoother, but for a swing arm, I would think a bolt and bushing would work ok. I haven't tried it though.

http://www.fleettrikes.com/tth2.htm#kingpins

Radical Brad

11-13-2008, 10:44 AM

Probably not much use for your project, but here is another home brew swingarm that can carry a 16 inch trailer wheel on an axle....

http://www.atomiczombie.com/gallery/bradgraham/arcturus/arcturus.htm

I needed to carry 500-800 pounds, and a 10+ HP electric motor, so it needed to be strong.

Brad

Locutus

11-13-2008, 12:29 PM

jimFPU

11-13-2008, 12:33 PM

Hey this may be an idea for a suspended Street Fighter...more Lego modeling required...

trikeman

11-13-2008, 01:30 PM

Looks like a great project. Those sealed bearings look like just what I need. Where can I buy them?

You can buy sealed bearings from TheBigBearingStore.com. That is where many of us got our pillow block bearings at a good price. You could also consider just buying a used swing arm from a small motorcycle. In fact, if you really want it beefy, and intend to travel at 30 mph+ speeds, you might just buy a small old motorcycle with a blown motor. That way, you could also use the brakes etc if you wanted to.

If it helps, here is a diagram of the swing arm on my Buell Blast motorcycle. You can see how they put it together using sealed bearings as Brad did.

http://www.atlantamusclecars.com/DeltaWolf/swingarm.jpg

The bearings in that diagram run about $7.50 from my Harley Davidson dealer, but you don't need any that large.

Locutus

11-13-2008, 01:38 PM

Could sealed bearings be used in the steering instead of chopped bike forks? It seems to me such a system might be stronger.

jimFPU

11-13-2008, 01:43 PM

I think it has something to do with the load bearing direction...vertical or horizontal.

TheKid

11-13-2008, 01:52 PM

I had sealed bearings for the steering in both my quad, and the original tadpole. They work well, and could be used with the method shown on fleettrikes.com, instead of the bushings. I used 1 1/4" EMT for the tubes, with flange bearings inserted into them. Flange bearings come in 1/2", 5/8", and 3/4". They're the same ones used for lawn cart wheels. I also used them for a swing arm on one of the tadpole mods. If I find the drawing for the swing arm, I'll post it. It was made with 16 ga. 1" and 3/4" square tube.

trikeman

11-13-2008, 02:27 PM

The only thing I would worry about with some sealed bearings is the axial load as a previous poster mentioned. Not all sealed bearings are designed to take an axial load. That is why head tubes have bearing surfaces that are slanted outward. Slanting them gives the bearings something to ride on that was designed to take it. Remember all the weight of the front of the trike will be riding on the steering tube, trying to push the bearings up. On my motorcycle they use cone shaped bearings with a cone shaped race, with does the same thing as the slanted races on most bicycle head tubes.

Something like these tapered bearings should work fine, since they can withstand loads in both directions.

http://www.thebigbearingstore.com/servlet/Search?category=Taper%20Roller%20Bearings

To borrow a picture from my motorcycle again - this time the steering head. Note the tapered roller bearings.

http://www.atlantamusclecars.com/DeltaWolf/taper.jpg

Locutus

11-15-2008, 11:32 PM

I'm concerned about the strength of the steering hardware as designed. Since the eventual total vehicle/rider weight may be around 400 pounds with batteries, motor, and full fairing, and I'll be regularly riding at speeds between 30 and 35 MPH, I think I'm going to have to beef it up.

Brad and Krew, do you have any suggestions for strengthening the steering/axles/hubs? For the tabs, I'm thinking of using a couple of hunks of 1-inch thick plate instead of 1/2-inch, and using 20mm axles and disk brake hubs. How much load can a setup like this handle in the fast riding conditions I'll be using it for, without flexing or bending?

Are there better ways to strenghen it? Perhaps a totally different design should be used in my case?

Radical Brad

11-16-2008, 04:52 PM

Locutus

11-16-2008, 06:53 PM

I'm just not seeing the StreetFox working for your desgin. Another factor you should really worry about will be the extreme side loading on the 26 inch rear wheel. At that speed and weight, you have problems.

I guess the only reason I suggested the DeltaRunner is because it will start to tip before you break anything, forcing you to learn the limits of the vehicle. The lower trikes will probably fail at extremes before they rollover.

You are dabbling in "motorcycle" territory with what you want, so bicycle parts are going to be put to the test. I actually do not have too many ideas for you as I am facing the same design issues with my electric high speed bike planned for next year.

Brad

I could be wrong, but I think the weak point of the design is likely to be the steering system, not the rear wheel. since there will be a hub motor on the rear wheel, the spokes will be shorter, and will have heavy duty spokes. the whole wheel will be built by Electric Rider with heavy duty spokes and double wall rim. Other than speed, I plan to be pretty easy on it, riding on paved straight streets and slowing down for the corners.

For the steering tabs, I thought 1" plate might be stiffer, and I could weld on some reinforcements made from 1/8" bar stock, something like this:

http://s59.photobucket.com/albums/g292/Locutus59/Workshop/th_img013.jpg

I went to the Exercar.com site and looked closely at the photos. the steering system seems to be similar to that of the street fox, and they have motorized/electric hybrid power taking the trikes to 35 mph and beyond. So I figure if they can do it, I should be able to also.

Locutus

11-16-2008, 07:21 PM

I'm thinking of buying this bike new, to hack for my Street Fox project:

http://www.kmart.com/shc/s/p_10151_10104_080W928574110001P?vName=Fitness+%26+ Sports&cName=Bicycling&sName=Bicycles

Here's a picture:

http://s.kmart.com/is/image/Sears/00610555000?qlt=90,0&resMode=sharp&op_usm=0.9,0.5,0,0

I'm considering this one because it has the strongest looking steel swing arm of all the department store bikes I've seen, the frame is steel, and it has two disk brakes that I can use on the front two wheels of the Street fox. They're Promax brakes. Are Promax any good?

I wonder if I can get by with just front brakes, or if I really need a rear brake for stable braking? Since the hub motor is incompatible with disc brakes I'll have to adapt the swing arm to accept a linear pull caliper brake.

I may have to go with a new donor because the used ones I've seen have been either unsuitable, too pricey, or just too cr@ppy. I'll find a couple of junk bikes for the steering head tubes though, hopefully.

Locutus

11-18-2008, 03:15 PM

The Mongoose Spark mountain bike shown in my last post is equipped with Promax disc brakes and Shimano drivetrain. Brad and Krew: What has been your experience with Promax brakes? Are they any good? I'm trying to decide whether it's worthwhile to buy this bike new for the swingarm and hardware, or if I should just get a used bike for its swingarm, and pay up for new Tekto or Avid disc brakes, and Shimano, Sram or other name brand drivetrain.

Locutus

11-24-2008, 12:10 AM

Brad and Krew,
In my continuing research in preparation for my electric Street Fox build, I've found that most commercial tadpole trikes have two front brakes only, no rear brake. I'm thinking of doing the same for my Street Fox, as it will be much simpler than a three brake setup. As for the potential for the trike to flip forward on hard braking, I think this problem may be mitigated somewhat by the weight of the 40 to 80 pounds of batteries I'll be mounting under the seat, and the weight of the rear hub motor. That just leaves the question of whether stopping power of the two front (disc) brakes will be sufficient for a total rider/vehicle weight in excess of 300 pounds, and speeds over 30 MPH. What do you all think?

darnthedog

11-24-2008, 12:35 AM

Depending on your state anything going over 25 mph and powered may require licensing and registration and insurance and might not be considered a bicycle.
Need to check your local MVD. Lot of people seem to be getting stung by some imported electric mopeds. The sellers are saying they don't need to be licensed, then the people get tickets. If it is for off road only then there is no issue typically. Now if the power is only pedal then there is no issue going over 25.

trikeman

11-24-2008, 01:10 AM

I don't think the braking will be much more complicated if you use one of the double levers that have been talked about on the forum before. That way, one brake lever will control both front brakes, and the other will control the rear brake.

If you are tooling down the road in excess of 30 mph and a car pulls out in front of you, it would be nice to have a backup brake (the rear one) in case the front brakes fail for some reason (cable break etc). The rear brake will also allow you to stop maybe 20% faster, which can be the difference between a trip to the hospital and just having to change your underwear. Motorcycle accident statistics show that one of the most common causes of accidents is a cager either turning in front of you from the wrong lane, or pulling out from a side street or driveway. The cagers are not going to show any more respect to a tadpole than the do a motorcycle (probably less).In other words, you need all the braking you can get at those speeds.

At 30 mph you are traveling 44 feet per second. It takes the average motorcyclist about 1 second to react to an incident, if they don't already have their hand on the brake. It takes them another 30-40 feet to stop after they react. Bikes are quite a bit lighter than motorcycles, but most bike brakes suck compared to the big hydraulic brakes on motorcycles, and bicycles don't have as much traction on the road generally, since they are so light.

Radical Brad

11-24-2008, 02:56 PM

Since you are going to absolutely need to convert to dual front disc brakes, I would probably go with the dual lever to the front and a decent rear brake as well. The dual lever will even out the braking force. Independant levers to the front will introduce a world of problems at your intended speed and weight.

at 30MPH and with all of that weight, there is no possible way the braking arm system I designed would hold up.

You will probably also need to remove all of the linkage and go with a USS steering configuration to lessen the mechanical advantage. At that speed, a tadpole will not feel safe.

My opinion is still.... delta.

Brad

Locutus

11-26-2008, 04:31 PM

Here's another idea I'm toying with: Since the kingpins (head tubes) need to be tilted in two directions, why not simplify the attachment to the crossmember by tilting the crossmember itself? This could easily be accomplished by inserting a 15 degree wedge (cut from 1.5" square tubing or a piece of steel plate) between the boom and the crossmember, then welding all three pieces together. Since the boom and crossmember would have to be welded together anyway, I dont foresee any loss of strength by doing this. I see this simple modification as having the following effects:

1. Fabricating the joint between the kingpin headtube and the end of the crossmember becomes a simple, rather than compound cut, making it easier and less time consuming to fab. I think this joint might be stronger also, because the pieces would line up along the axis.

2. The boom will be slightly lower at the front end, making the seating slightly lower and more forward tilting, in the absence of any compensating seat adjustment.

3. Center of gravity will be slightly lower, improving handling.

Thoughts on this?

trikeman

11-26-2008, 05:50 PM

Locutus

11-26-2008, 07:29 PM

Cutting a 15 degree wedge that small and welding it all back together doesn't sound very easy to me. I think I like TheKId's method in this post better

http://forum.atomiczombie.com/showthread.php?t=1474&highlight=fishmouth

Thanks, Trikeman. I checked it out and it looks like that might make it easier. I'll try some modelling to get the feel for it. Maybe I can try a combination of methods. Here's what I was thinking of:

http://i59.photobucket.com/albums/g292/Locutus59/Workshop/img014.jpg?t=1227745026

Alternately, I could simply build it so that the boom itself is at an upward angle from rear to front. I think combining about a 6 to 8 degree boom angle with Kid's method would yield a near-15 degree angle at the kingpin. The boom angle can be adjusted by varying the placement of the rear suspension spring attachment tabs. Of course I'm guessing about the numbers. I haven't run any calculations at this point.

Radical Brad

11-27-2008, 01:02 AM

You could also hack a bit out of the boom instead of the wedge. Tack it in the front, set up the frame to check angles, then weld the rear of the joint.

Brad

Locutus

11-27-2008, 11:40 AM

You could also hack a bit out of the boom instead of the wedge. Tack it in the front, set up the frame to check angles, then weld the rear of the joint.

Brad

Seems to me that would reduce the strength of the frame. If not, why to you think that would be stronger than inserting a wedge?

comreich

11-27-2008, 01:00 PM

Coming out of lurk mode for this one. Locutus, I've done the same slice & weld on a trike I built (somewhat different style) to correct a rather large negative camber.

This first picture shows the wheels really tipped in and, while it was pretty fast, it chewed tires something awful.
http://comreich.ods.org/~reich/trike/2008-05-11%20-%20Front.JPG

So, I cut a slot close up to the kingpins, bent the cross member closed to get the wheels vertical and then re-welded. It's plenty strong. In fact, I cut one of them wrong and ended up cutting through the part of the cross member that was supposed to bend. Even that hasn't affected the strength of the re-welded arm.
http://comreich.ods.org/~reich/trike/new/2008-07-05%20-%20Camber%20fix%20closeup.jpg

Effectively, the welded joint is stronger than the material surrounding it, so cutting a wedge into the boom and bending it will probably make it that much stronger. And as trikeman said, cutting the tiny 15 degree wedge to slip under is probably more hassle than it's worth. Strong, but really fiddly.

comreich

Radical Brad

11-27-2008, 01:10 PM

You don't have to worry about frame strength, especially in this design. Both methods would be just fine. Here is a wedge-cut cross boom on the SpinCycle....

http://www.lucidscience.com/temp/scframe.jpg

If you knew what I did to this poor thing, you would not be worried! Even when I had myself and two adults (big kids) standing on each side of the boom, it did not hurt anything when I bashed directly into a curb and rolled the thing. I even bent shopping cart casters right over but never bent the frame.

I still say you biggest concern is the amount of even braking you will need and the fact that my steering design is not going to work well at your intended constant speed. You really need to re-think the entire steering system.

Brad

SirJoey

11-27-2008, 04:02 PM

Here is a wedge-cut cross boom on the SpinCycle....
If you knew what I did to this poor thing, you would not be worried!

You tell 'em, Brad! Mine's built exactly the same way, per the plans, & I'm blastin' down the road
at over 30 mph, with a 200 lb trailer LITERALLY hangin' off the back of mine! :eek:

http://img356.imageshack.us/img356/2839/thanksgivingsigsmalllu5.jpg

Locutus

11-27-2008, 04:09 PM

I still say you biggest concern is the amount of even braking you will need and the fact that my steering design is not going to work well at your intended constant speed. You really need to re-think the entire steering system.

Brad

Yeah, I'm thinking of installing handlebars with the head tube going through the boom just in front of the crossmember, and tying into the tie rod. I'll probably have to use two tie rods with each attaching to the steering tab in the middle. And maybe fatter tie rods and larger ball joints. Wouldn't the steering tab need to face backwards and be the same length and angle as the ackerman attachment points, and also wouldn't the steering tube need to be along a straight line between the kingpins? Like this:

http://i59.photobucket.com/albums/g292/Locutus59/Workshop/img015.jpg?t=1227819683

As for braking, I'm planning to put disc brakes in front, and a brake in back too but I don't know yet whether that will be disc or caliper.

Radical Brad

11-27-2008, 09:50 PM

There is a bit more to it than that, but it is not too hard to figure out with a little real world testing. Here is some good ground work on steering...

http://www.eland.org.uk/steer_intro.html

I figure my designs out using my own calculations, some home brew computer software and actual drag tests, but you can get a lot from that page.

Also, you want mechanical disadvantage so the trike does not feel as twitchy at high speeds. I am guessing some tests and redesign is going to be necessary for what you want to achieve. That's part of the fun though.

Brad

Locutus

11-28-2008, 02:18 AM

Thanks, Brad. That's good information, although I think it will take some study before I understand those spreadsheets and how to use them.

I've been thinking about the steering issues, and it occured to me that perhaps I could adapt the steering system in the California Commuter (for which I also have plans) to the Street Fox, although that would make it a very different machine. I'd post some images from the plans but that would probably violate copyright. Instead, I made my own sketch to give an idea of the system used. Essentially, it consists of a front swing arm with dual shock absorbers, tied in with a dual joystick lever steering mechanism. Here's my sketch:

http://i59.photobucket.com/albums/g292/Locutus59/Workshop/img016.jpg?t=1227856501

The California Commuter is designed to travel at freeway speed (60 MPH cruise). I don't know if this system would address the mechanical advantage/disadvantage issue you mentioned, but if it's good enough for the freeway, it should be good enough for a 35 MPH city street. I'd probably need to make it a bit smaller and lighter weight for the Street Fox build.

I could probably just build the steering system without the suspension swingarm to keep it simpler.

savarin

11-28-2008, 04:07 AM

if I could chip in here.
Have a look on this site for all 16 articles regarding "another hpv" download them and print them out. Its a very informative collection of ideas that work very well and then decide how you want it all to go.
Your after constant high speed work and this system seems to have it all worked out.
http://www.autospeed.com/cms/A_108917/article.html

trikeman

11-28-2008, 05:13 AM

Locutus - if your actual metal machines (once you start making sparks) are as nice as your drawings, they will be outstanding. Do I smell architecture training somewhere in your background?

Sparky

11-28-2008, 10:35 AM

those steering componets look like go kart stuff. it might be heavy and expensive, but it is made to handle some abuse.

a thought on a steering damper- look to the big 4wd trucks. they always use em to get a handle on bump steer caused by massive tires. obviously you dont need something as big, but perhaps the info could be relevant.

Locutus

11-28-2008, 04:29 PM

Thanks, Savarin. Lots of good information there. There's actually two projects, I consolidated the links for all of them and will study them carefully.

I just made a major score. See the photos on my "Preparations are Progressing" thread.

Radical Brad

11-28-2008, 05:02 PM

The "Commuter" steering seems to lack centerpoint and caster angle, so it will not be a good choice for anything but slow moving lawn equipment. The linkage could probably be adapted though.

Brad

Locutus

11-28-2008, 08:29 PM

The "Commuter" steering seems to lack centerpoint and caster angle, so it will not be a good choice for anything but slow moving lawn equipment. The linkage could probably be adapted though.

Brad

Au contraire Brad. here's a detail sketch I whipped up to show how the CC is designed with both center point and caster angles built in:

http://i59.photobucket.com/albums/g292/Locutus59/Workshop/img017.jpg?t=1227921508

And here's an image from one of the trike build articles Savarin turned us on to. It shares some traits of the CC steering, i.e., the levers, but the rest of the linkage is quite different, with the intention of minimizing bump steer:

http://us1.webpublications.com.au/static/images/articles/i30/3039_3mg.jpg

Notice that the lever pivot points are attached directly to the underside of the seat frame. Mechanical disadvantage is also deliberately built in.

You can read the article here:

http://www.autospeed.com/cms/A_3039/article.html

Perhaps some of these ideas can be used to good effect on the Street Fox?

At the end of the article from which the above photo was taken, the author has these comments about this steering system:

"This steering system gives the following positives:

Steering handles have a lot of travel – ie a slower ratio steering

The ability to change the leverage ratio manually by gripping the rods high or low

The ability to easily change the leverage ratio during development by having differing mounting points on the lower part of the steering levers for the push/pull rods

Conventional ‘one lever moves back as the other moves forward’ steering, where pushing forward on the left-hand lever and/or pulling back on the right-hand lever causes the trike to turn right

And the negatives?

A slight arc of forward/rear movement of the inner ball-joints

Changing Ackermann compensation which complicates this aspect of design

The use of 8 ball-joints in the steering system

Increased weight over other approaches

A greater possibility of deflection in the steering components because of their lengths and the fact some are subject to bending forces not just compression/tension.

It’s a measure of how difficult I found the steering system development that I was not at all confident that even this system would work well until I could test it on the road. So it was with immense relief that I found it to work very well!"

Radical Brad

11-28-2008, 09:58 PM

Ok, much better!

Yes, that is a nice setup. I am doing something very similar on the StreetFighter-II, but personally did not like the front/back lever steering.

I found the lever action to be counter intuitive, as it does not relate as well as side to side action. On SF2 I am going with a left/right dual lever so the steering will respond in the direction I point. Front/back levers just don't relate well with me, although that is just my own observation.

The design is great though.

Brad

Locutus

11-28-2008, 11:27 PM

Or how about this suspension and steering? Same author, second HPV.

http://us1.webpublications.com.au/static/images/articles/i1090/109038_4mg.jpg

TheKid

11-29-2008, 01:44 AM

The Commuter steering geometry was specifically designed to eliminate bump steer that's inherent with front suspension. All the angles, lengths of steering components, track, travel, etc. were carefully engineered. Any deviation of any component will radically affect the handling. When using a design as sophisticated as that, at the speeds you in tend to achieve, it's important to accurately fabricate your components according to those plans.

savarin

11-29-2008, 04:22 AM

that second article is the set I was alluding to and he appeared to have solved all the bump steer problems and have excellent handling, suspension and steering.
Complex but for a high speed machine for long distance I would think well worth while.

savarin

11-29-2008, 04:26 AM

you will not that the majority of his tubes pass through the one another so they are welded on both sides.
He has an article regarding spreading stresses so they dont congregate at one point leading to catastrophic failure. An interesting read.

Radical Brad

11-29-2008, 11:33 AM

I really like the second system.

Brad

TheKid

11-29-2008, 01:02 PM

Yes. The second system is what I was referring to. I toyed with that system on paper while my leg was healing in the summer of '07, thinking I might want to go with it for a motorized trike. Bump steer is reduced as much as possible, but any deviation must be compensated somewhere else. For instance, if you want a wider or narrower track, it must be compensated for somewhere in the design. So if you want to build a system like this without having to do any more engineering, it's best to follow the plan exactly for best results. In order to eliminate bump steer, the travel must be absolutely vertical, in a way that camber and caster remain constant at all times. The best that can be achieved is reduction of bump steer to a point that it's unnoticeable.

Locutus

11-29-2008, 01:35 PM

Here's another view. The green arrow shows where the weight of the rider is transferred directly from the seat to the suspension. I think this is one of the most ingenious parts of this design, because the front suspension supports the weight of the rider more directly, rather than through the rest of the frame.

http://us1.webpublications.com.au/static/images/articles/i1087/108767_10mg.jpg

Locutus

11-29-2008, 02:40 PM

Here you can see the rear spring directly supporting the back of the seat, and thus the rider. Notice that the rear swing arm pivot is way forward under the seat, allowing the spring travel to be similar to the rear wheel travel (low motion ratio).

http://us1.webpublications.com.au/static/images/articles/i1087/108796_4mg.jpg

Radical Brad

11-29-2008, 11:10 PM

I have always like this trike as well, but the machining would be intense...

http://mairas.net/recumbents/S327/

Brad

savarin

11-30-2008, 12:41 AM

I have always like this trike as well, but the machining would be intense...

http://mairas.net/recumbents/S327/

Brad

Me too, really high geek factor. More bragging rights than you could poke a stick at. :cool4:

Locutus

11-30-2008, 03:16 AM

More views of Julian Edgar's full suspension trike frame, from Bent Rider Online. I know this isn't an AZ design, but I think these pictures are good idea generators. We hackers can make whatever mods strike our fancy, after all.

Note the lateral and longitudinal braces in the next two photos, marked by arrows. Not only do they add strength to the frame, but also stiffness, reducing flex considerably. the longitudinal brace is removable to allow for steering installation.

http://i122.photobucket.com/albums/o272/suspensiontrike/finalframe2.jpg

http://i122.photobucket.com/albums/o272/suspensiontrike/finalframe1.jpg

This one better shows the suspension design. The central part of the frame reminds me of the thorax of a spider, with the appendages branching out from a compact area. This allows the stronger (and heavier) frame components to be used sparingly.

http://i122.photobucket.com/albums/o272/suspensiontrike/Air150steeringandfrontsuspension.jpg

Locutus

11-30-2008, 01:06 PM

Here's a quickie sketch I made that is intended as a front suspension mod idea for the Street fox, based on Julian Edgar's full suspension trike, but using hacker materials like steel square tube and scavenged bike parts. Let me know what you think.

http://i59.photobucket.com/albums/g292/Locutus59/Workshop/img018.jpg?t=1228067769

SirJoey

11-30-2008, 01:12 PM

Dude, you are gonna be the SUPER BUILDER from Mars! :punk:

http://img233.imageshack.us/img233/539/christxsigsmalloq2.jpg

Radical Brad

11-30-2008, 02:03 PM

Locutus

11-30-2008, 02:41 PM

Looks like a good plan. 3 things that came to mind...

1) If using cycle springs, you will need to move them way closer to the axis or go with much softer gocart springs.

2) As the arm lifts, the wheels will tilt outward, causing them to skid or flex so if there is a lot of travel, this could weaken or cause a rim failure. A change in the pivot axis or addition of a wishbone support would help.

3) Tie rods will have to run parallel with the swing arms or suspension induced toe-in will occur. 4 control arms, perhaps?

I think all of these things can be addressed in your design.

Brad

Brad, here's what I'm thinking to address the three issues you brought up:

1. I think I should try to keep the springs out board, to keep them as much in line with the weight transfer from seat to hub as possible. I want them angled so as to optimize the vertical suspension travel. If that means using softer springs, so be it. Perhaps I could use springs designed for lighter riders, say, from a kid's suspension bike. Although I think they may be too short. I'll probably go with your suggestion of using go cart springs. I'm also toying with the notion of using a suspension fork, straddling the suspension at an angle, or splitting it and using half on each side, port and starboard. But I think they might be too long. Dual springs straddling the swing arm would eliminate the torsion that would occur from using only one spring at the side.

2. Julian Edgar addresses this in his articles. Since his air springs didn't provide sufficient damping, he was using lateral wheel travel to his advantage. The lateral travel in fact provided the damping effect he was after. The downside according to him was increased tire wear. He didn't report any damage to frame or rims. I wouldn't need the damping effect if I used dampened springs, but I also don't think there will be a lot of lateral travel with the length of the swingarms I'd be using and the well-maintained roads I'll be riding on.

3. I'll probably end up using a Greenspeed style steering rod system to optimize this, even though it doesn't optimize mechanical disadvantage. If that turns out to be inadequate, I may convert it later to the lever system I illustrated earlier.

Locutus

11-30-2008, 03:01 PM

Another thought I had about building a front suspension is that perhaps I won't need 20 mm axles, due to the fact the the majority of the shock loads will be aborbed relatively smoothly by the springs, rather than suddenly by the axles. To put it another way, the shock will be transferred to the springs through the axles. In light of this, I'm wondering if stock kingpin assemblies with standard 12 mm axles, such as those sold by Greenspeed and other trike manufacturers, would be adequate on a front suspension trike, even at the 30 MPH + speeds I'll be riding? This is what Julian Edgar used on his. He put it through some pretty rigorous testing but didn't report any axle damage or failure.

Locutus

11-30-2008, 03:20 PM

Hey, I wonder if any of these would work?:

http://www.jackssmallengines.com/gokaz_spindle.cfm

Probably not, as far as complete assemblies. They don't appear to have proper angles for center point steering or camber. but perhaps some of the individual parts could be useful?

Locutus

11-30-2008, 06:04 PM

Here's a revised sketch of my front suspension idea. I think this will work much better, and elminates torsion load from offset shocks. By the way, what spring rating do you think I should use? I've been looking at budget shocks from 350 to 1000 lbs. ratings, with travel from 1.5" to 3". Considering the rider weight will be distributed over three shocks, I wouldn't think I'd need really strong ones to acheive the required support, while also providing a smooth ride.

Here's the sketch:

http://i59.photobucket.com/albums/g292/Locutus59/Workshop/img020.jpg?t=1228085653

savarin

11-30-2008, 06:46 PM

anyone seen these?
not much travel but how would it work in real life.

http://i154.photobucket.com/albums/s258/savarin48/recumbent/9.jpg

http://i154.photobucket.com/albums/s258/savarin48/recumbent/11.jpg

Radical Brad

11-30-2008, 07:37 PM

Looks like you could make it by pulling appart some kid's bike suspension springs. It does solve the wheel scrub and toe in problem quite easily. Maybe I will try something like that next year.

Brad

Locutus

11-30-2008, 09:41 PM

Savarin,
I like that suspension design and think it would be relatively simple to build, and solve the problems Brad mentioned. But it looks like vertical travel would be only about 1/2 inch, 1 inch tops. I'm looking for up to 4 inches travel in my design, to be able to suck up the largest bumps and handle rough road with aplomb.

John Lewis

11-30-2008, 10:50 PM

[QUOTE=savarin;15025]anyone seen these?
not much travel but how would it work in real life.

http://i154.photobucket.com/albums/s258/savarin48/recumbent/9.jpg

Greenspeed do or did one like this. I've seen it round here. It uses a red elastomer (urethane ?) instead of the springs.

I think the same idea is used by Timothy Smith. Take a look round on his site

http://www.ihpva.org/people/tstrike/home.htm

John Lewis

Edit: Hang on . That is Tim's trike. Have a look at his site anyway for details.
Here it is:
http://www.ihpva.org/people/tstrike/trike3.htm

savarin

12-01-2008, 03:46 AM

thanks John, I found that a long time ago but never made a not of who it was.

TheKid

12-01-2008, 10:02 AM

Tim Smith has a lot of good ideas. In fact, the first tadpole I made was based on some of his designs, with an added rear suspension triangle I have from a 20" bike. (It later became my Streetfox.)
The problem with most of these front suspension designs, is that they lack the two pivot points needed to keep the wheels perpendicular to the boom at all times. That's why tires wear out more quickly, or as Brad states, there is danger in damaging the rims. The few that are complicated are that way for two reasons. A safe stable ride, and comfort. 4" of travel is a lot, with the average being about 1 1/2". There's a lot to consider, including bottoming out the frame when designing a suspension system. One aspect also deals with the angle of travel, which must be along the line of the shock absorber. There should be no lateral forces on the shock whatsoever, or the shocks will be damaged beyond repair. If you want a simple design, such as used by Tim Smith, which is similar to the Crank-It mountain quad, the travel must be limited in order to maintain stability. Added comfort can be achieved by using seat suspension. The trike you showed earlier is designed for both comfort and stability, with plenty of damping without excessive travel.

Locutus

12-02-2008, 08:58 PM

Ok, so two of my smaller chromoly frames are almost identical: The Giant and the Raleigh. I'm trying to think out of the box a bit here. I thought that if I cut the frame so that the tube connecting the BB and the steering tube is left intact, then turn it upside down, I might be able to use it like that as the pivot crossmember. The angle is about 35 degrees, but I'm thinking that if I tilt it vertically down slightly, and use the 45 degree crossmember angle, I might be able to achieve a 15 degree angle both laterally and fore-aft. Here are a couple of illustrations of what I'm talking about. First a photo showing the cuts:

http://i59.photobucket.com/albums/g292/Locutus59/Workshop/Bikes.jpg?t=1228268820

Here's a sketch to show where those two pieces would go:

http://i59.photobucket.com/albums/g292/Locutus59/Workshop/img022.jpg?t=1228268923

The tube is about 22 inches long, not including the BB and the Steering tube. The down angle would cause the seat to ride higher, but I think it would also have a somewhat wider track than the standard Street fox, so the handling should even out. Also, if the angle is right, the suspension arc of vertical travel may move above and below the level plane about evenly, reducing suspension induced lateral scrub of the front tires. Or so it seems to me. What do you all think?

Locutus

12-05-2008, 02:31 AM

I've been thinking about the suspension some more. Since there will be three shocks, each of them will only need to take 1/3 of the total load. The total sprung rider/vehicle weight shouldn't exceed 300 pounds, so that's 100 pounds nominal load per shock. Double that as a rule of thumb for when the wheels roll over bumps. So that's 200 pounds per shock. Now, the softest bike shock I've found online is 650 pounds of load per inch of compression. I understand that to mean that If I were to position the shock vertically, and place 650 pounds on top, it would compress one inch. So I think I should position the shocks in such a way that leverage will be increased on them. Since I want to have a 3 to 4 inch vertical wheel travel, and dynamic bump load will be in the neighborhood of 200 pounds, I need to position the shocks in such a way as to translate 1/3 of an inch of shock travel into a few inches of travel at the wheel, lets say 2 inches. So I came up with a kind of zig-zag suspension mod. Here's a sketch:

http://i59.photobucket.com/albums/g292/Locutus59/Workshop/img023.jpg?t=1228461282

So that's the general idea. I'll need to quantify the postioning and figure out how to prevent pinching situations.

Now another factor I realized probably needs to be considered and compensated for is the arc of travel of the suspension cross member. This wil depend on the positioning of the pivot. If I align the pivot with the boom, viewed from the front there will be a curved arc of vertical travel at the wheel and a small amount of lateral travel. Viewed from the side, the vertical travel will be straight up and down. I think this will be the case even if the suspension crossmember is angled forward, as in this sketch:

http://i59.photobucket.com/albums/g292/Locutus59/Workshop/img024.jpg?t=1228461720

However, if the pivot is also repositioned to angle forward, the dynamic changes. The vertical wheel travel will be in the form of an arc whether viewed from the front or the side, and the lateral motion will also be at an angle, as in this sketch:

http://i59.photobucket.com/albums/g292/Locutus59/Workshop/img025.jpg?t=1228461901

So I guess the question becomes: Will this have any impact on how the trike rides, handles or steers, and if so, what should be done about it and how can it be quantified?

TheKid

12-05-2008, 10:13 AM

You need two pivot points to avoid changing the camber of the wheel on uneven ground. Even smooth roads are graded to allow runoff of rain. A second pivot at the kingpin will keep the wheel vertical. In addition, the springs must be set so they allow travel where the road grades lower. Without the weight of a rider, the bottom of the wheels should camber slightly inward. (Positive camber) That will allow the wheels to revert to a vertical position when the weight of a rider is added. For enhanced handling at higher speeds, some engineers advocate slight negative camber when the rider is on the trike.

rickairmed

12-05-2008, 10:26 AM

Locutus

12-05-2008, 10:42 AM

Locutus the only real problem I can see is your shock angle the bottom of the shock needs to be out on the lower arm and the top needs to be in on the frame otherwise it wont load or unload properly . I woud say in its current position it will bind and the suspension will not travel properly as the lower control arm moves the shock needs to move in and out in the current setup I dont think it will do that put the bottom of the shock out closer to the spindle.

Rick

You may be correct about that. Perhaps a better way would be to mount the shock similar to how I illustrated in my Nov. 30 post, but at a shallow angle to provide the needed leverage. That will of course limit the vertical travel to maybe 2 inches, but for the intended use (commuting on well-maintained paved roads) that may be all that's needed. I might also try front suspension forks, because they are softer. I could split one in two and put half on each side. The problem with those is that they are longer than the spring type so fit could be an issue.

TheKid

12-05-2008, 10:44 AM

I tried that a while back. It worked, but was bulky.

rickairmed

12-05-2008, 10:50 AM

Locutus

12-05-2008, 11:00 AM

Yes your Nov. 30 post would work properly and you may find 2" of travel will be plenty .I might try to play with an upper and lower control arm desighn for you with as Kid said pivot points at the spndle and on the frame which as he said would alow the spindle( kingpin ) to travel in a straight line up and down . I have a big job starting today so it may be a few days before I can play with the desighn.

Rick

Thanks. I may try building a mockup of one side of the suspension for testing, before actually building a trike like this. I want to get the angles and positioning right to acheive the correct amount of travel. A mockup will allow me to experiment.

TheKid

12-05-2008, 12:00 PM

Here's an illustration of what happens with one pivot point:

http://i192.photobucket.com/albums/z66/edpol_photos/suspension/100_0209Small.jpg

Upper and lower control arms is the way to go. It allows the use of a spindle on ball joints, eliminating the old fashioned kingpins. Inclination is achieved by using a longer lower arm. Making the arms in an A Frame configuration will greatly add to the strength. Heavier, yes. But that design will improve safety when using a powerful motor at the speeds you want to achieve.

Locutus

12-05-2008, 01:09 PM

When Julian Edgar built his first machine (articles referenced earlier in this thread), he did use double swing arm (wishbone) suspension, but even with aluminum he found it to be too heavy. His semi leading single swingarm design in his second machine was much lighter, balanced out the various steering issues and was strong enough for speedy downhills on rough roads. So unless I can come up with a dual swing arm design that compares favorably in weight to the single swingarm, I'll probably go with the simpler-to-build single swingarm.

Hmmm... I wonder if the skinnier rear triangle tubes from two chromoly road bikes would be strong enough to use for the swingarms in a dual design, considering the load transfer will be through the shock absorber into the seat? Maybe I'll come up with a sketch for that this weekend....

TheKid

12-05-2008, 02:44 PM

The second design seems to be very different than your drawings. There are comonents he used that keep the wheels vertical, particularly the design of the anti-roll bar, and the springs that are built into the rigid arms that the seat mounts to. Combined with the 30 degree angle the crossmember arms are attached to the boom, all the components pivot in a way that prevents bump steer. With the first aluminum design, he used solid blocks of aluminum that are quite heavy compared to tubing. It may be possible to make control arms from steel or aluminum tubing that are a bit lighter, but it would take a lot of experimenting.
Another thing to consider is that "too heavy" is relative to the designer and his or her goals. For instance, if I want a vehicle that I'll be using with either pedal assist or the motor only at all times, weight isn't an issue at all. The motor will in essence "lighten the load" when pedalling. However, if I want a vehicle that will use a motor only on steep hills, the I'll want it as light as possible. Suspension is nice to have, but It's probably much easier to apply it to the seat. A less than optimum steering suspension leads to a vehicle that's not much fun to ride, and could prove to be dangerous. I took the suspension fork off my DR because there was too much wheel flop. It was easier than changing the head tube angle. The difference isn't that noticeable, and with slightly less tire pressure, there's no noticeable difference at all. If you want a smoother ride, there are far easier ways of achieving it than building a full suspension trike. On the other hand, if you want the challenge, then the only option is building a suspension trike. You also might want to look into the Leitra, which uses a McPherson strut type of suspension.

Locutus

12-05-2008, 03:05 PM

Kid,
I was planning on a anti-roll bar, but didn't include it in the sketches for clarity's sake. My design is intended to emulate Edgar's second trike, but using less expensive shocks. His airbag shocks were $200 or $300 apiece, if I recall correctly, compared to $20 or $30 apiece for the shocks I'm proposing. I do have a rigid crossmember in my sketches which are to be tied in to the seat structure. They include additional bracing for extra strength.

TheKid

12-05-2008, 03:18 PM

Then it will fill the bill nicely. And a lot cheaper!

Locutus

12-05-2008, 04:40 PM

I found this online, looking for Chromoly tubing.

http://www.midwestcontrol.com/buy.php?item=2268

I was thinking it might be good for axle material. But .75 inch OD is just slightly less than 20 mm. So I'm wondering if it will fit well inside a 20 mm Bitex or similar hub, or if I'd need to go to the next larger size (.875 in) and machine it down on a lathe to 20 mm? In that case I'd need to get at least .125 wall thickness, or thicker even.

If anyone knows where to get chromoly tubing that will exactly fit a Bitex or similar 20 mm through hub, please let me know.

Oh, and by the way, I've been trying to reach Bitex without success. Probably I'm just contacting the wrong email and phone number. Anyone know how to reach someone who can actually sell and ship the hubs to me?

TheKid

12-05-2008, 08:31 PM

Ms. Judy Hsieh/ Mr. Stefan Hernandez
3099 Falling Waters Lane
Lindenhurst, IL 60046
E-mail: hsiehjudy@gmail.com
sherna4896@yahoo.com

I sent an email to Judy, who sent me the prices of the hubs. Apparently, all you have to do is send her a check to the above address, and she has the hubs drop shipped to you.

Locutus

12-05-2008, 08:59 PM

Thanks, Kid. I just shot off an email to both of them. I'm still trying to figure out the axles though. I asked them if they know where I can get them, perhaps they know.

Locutus

12-06-2008, 01:57 AM

Julian Edgar has published two articles on his third trike build, dubbed the "Air 150 Recumbent trike." Great information, including details of how it was built and specifications. After reading, I felt like I could run out to the garage and build one myself. Here are the articles:

AIR 150 RECUMBENT TRIKE

Part 1 – Its Design and Build

http://www.autospeed.com/cms/A_109615/article.html

Part 2 – Testing and Evaluating the Design

http://www.autospeed.com/cms/A_109618/article.html

Hopefully these have given me sufficient additional information for me to incorporate many of his ideas into my Street Fox build. Mine will be a garage hacker's version though, using a lot of scrounged parts.

Locutus

12-08-2008, 04:15 PM

I found this bike on Craigslist:

http://images.craigslist.org/1191f11293n63kf3la8c8a9659132e2111906.jpg

Called the seller up, he says it's an aluminum frame. I've been passing up aluminum bikes, but I really need to find a good rear suspension swingarm, and this bike is said to be almost new. I could use some of the other components on it too.

So my question is, If all I need is the swingarm and shock, how can I fasten it to a steel frame? Normally a hacker would use the bottom bracket tube from the original frame, but since it's aluminum in this case, I'd need to find an alternate attachment point.

Please provide your ideas ASAP because if I can use this bike I'd like to snap it up quick, before it's gone. Thanks.

trikeman

12-08-2008, 06:15 PM

A lot of "aluminum" frame bikes have steel swing arms. I check em with a magnet.

TheKid

12-08-2008, 06:34 PM

You could easily use the swingarm whether it's aluminum or steel. You'll need a steel tube on the rear end of the boom that's the same size as the tube holding the swingarm on the bike. In my case, I had to make one by cutting a slice out of a larger tube then pinching it shut and welding the seam. You'll need to do this even if the swingarm is steel, because the tube it attaches to on the donor bike is aluminum. Then you'll need to make a piece for the shock to mount on the seat tube. I made one with two short pieces of angle iron welded to the frame, then drilled the holes for the shock.

jimFPU

12-08-2008, 09:32 PM

Locutus, I bought 3 of the same kid of bike. They most likely have the steel rear triangle. If you look at the Not-so-Baby Fox thread, you'll see my hack with my AL bike like that...pretty good components too, for the Craigslist price...

TheKid

12-08-2008, 10:19 PM

It's a lot easier to just cut a slice out of a tube and clamp it in a vise, then weld the seam. You just insert it into the holes you drilled in the frame and weld it in. It took less than 20 minutes to do the whole thing, and there's no need to wrap a steel strip around the back. If you ever have to replace the bushings, just take the rear off and pop them out. On another tadpole, I had a rear triangle I built from scratch, and used a piece of 1 1/4" EMT for the pivot tube. I used 5/8" flange bearings instead of bushings.

Locutus

12-08-2008, 11:10 PM

Thanks guys for your inputs. I wasn't too concerned about whether the swingarm itself was aluminum, just about the attachment point on the frame. But from what you are saying, it sounds like there are some pretty straightforward workarounds. I was also toying with the idea of making my own swingarm, maybe one similar to the Air 150 Recumbent Trike. Also, if I don't have to cut up the aluminum front part of the frame, maybe someone else can use it.

jimFPU

12-09-2008, 03:31 PM

I put the rest of my AL frame in my recycle bin...

Locutus

12-10-2008, 08:11 PM

I've been giving some thought to the issue of camber changes with the front suspension. Julian Edgar's design creates increased camber on bump and cornering deliberately, so maybe a little of that is a good thing. But I came up with a simple solution that makes the wheel move straight up and down when viewed from the front or back, but retains the arc of travel when viewed from the side. Thus, the angle that changes is in the trail only. The solution was in the axis of the front swing arm pivot. The axis is positioned perpendicular to the boom. Here's a sketch to illustrate:

http://i59.photobucket.com/albums/g292/Locutus59/Workshop/img028.jpg?t=1228955814

I also figured that the shock would have to be repositioned to a fore/aft orientation due to the change in the motion of the swing arm relative to the rigid crossmember. This might have a secondary advantage: to create a soft brace against rearward forces of bumps in the road on the suspension. See second sketch:

http://i59.photobucket.com/albums/g292/Locutus59/Workshop/img027.jpg?t=1228955130

I wonder what kind of side effects this design change might have. More brake dive perhaps? I would think this would completely eliminate bump steer. What are your thoughts, Krewmembers?

On another front, I've been talking to Bitex about brakes. It seems that they offer a paired set of hydraulic disc brakes for about $70, and the Bitex rep is looking for me into the possibility of modifying the system to provide balanced three-wheel braking with one lever. It would have to be modulated to provide more power to the front wheels than the rear wheel, otherwise the rear wheel may skid prematurely. I'll post findings here when I have them. Meanwhile, here's a diagram of their brake system for your viewing pleasure:

http://i59.photobucket.com/albums/g292/Locutus59/Workshop/img029.jpg?t=1228956881

Locutus

12-12-2008, 04:09 PM

Any feedback from the Krew on my last post would be greatly appreciated. I'd like to know if anyone can foresee a problem with the latest suspension idea. :confused:

Odd Man Out

12-12-2008, 06:32 PM

Any feedback from the Krew on my last post would be greatly appreciated. I'd like to know if anyone can foresee a problem with the latest suspension idea. :confused:

You Sir are a NASA engineer compared to me... I dare not comment without embarrassing myself :rolleyes4:

jimFPU

12-12-2008, 08:04 PM

Something you might consider...why hasn't this been done before?

One thing I see is that you are thinking that the pivot point and the suspension cross member (SCM) are always in the same position relative to where it is in the drawing. If you look at it from the side and (here is the theory part) if you could rotate it 360 degrees it would make a cone shape as it traveled around.

So, as you move the SCM up and down the shock would also have to slide/move in/out on the SCM. It seems to me this would cause some binding...I'll have to build a Lego model...

jimFPU

12-12-2008, 08:08 PM

Not enough of the right kind of peices for a Lego model...any one know how to use True Space better than me, maybe Brad can chime in...

savarin

12-12-2008, 09:34 PM

what is/are the problem/s with parallel links on the front suspension as most racing cars use?
weight?
strength?
under/over steer?
bump steer?

I dont know enough to make an evaluation.:dunce2:
But it seems that the wheel camber would remain the same as the wheel would rise and fall vertically, the contact point on the tyre (steering axis) would remain the same, the width of the front would shorten slightly on bumps.

TheKid

12-12-2008, 10:32 PM

There's still a change in both caster and camber when hitting a bump or encountering unlevel terrain.
Stick with the tried and true unless you plan on making numerous mods until you get it right. Most paper plans without the use of a scale model or a computer program to demonstrate the dynamics require changes. Better to build a scale model if possible than to deviate from a proven design. Unless of course, you plan on making suspension design a project in itself.

savarin

12-12-2008, 10:58 PM

There's still a change in both caster and camber when hitting a bump or encountering unlevel terrain.

why would they change with a parallel vertical movement? Wont the wheel angle tilt remain the same irrespective of its position?

Stick with the tried and true

Ah! the way to stagnation, seems a strange comment to use in this forum

unless you plan on making numerous mods until you get it right. Most paper plans without the use of a scale model or a computer program to demonstrate the dynamics require changes. Better to build a scale model if possible than to deviate from a proven design.

But we dont have an optimal design, just some methods that appear to work ok.
I wish I had the knowledge to follow the dynamics but I dont so I'm drawing it up in truespace, I will animate the movement and place it on here for discussion.

rickairmed

12-12-2008, 11:54 PM

The camber wouldnt change in the lastest drawings but the caster would although I dont think it would change drastically unless of course you were running it on Mountain bike trails .

Rick

Radical Brad

12-13-2008, 12:03 AM

TrueSpace is great for testing mechanical designs. Just move the axis and do some test rotations to see things working. You can even set IK chains (Inverse Kinematics) - I do that a lot.

http://en.wikipedia.org/wiki/Inverse_kinematic_animation

Brad

Locutus

12-13-2008, 12:26 AM

OMO, I'm no NASA engineer, or any engineer for that matter. If I was, perhaps I'd already know the answers here, but I'm just slogging through trying to figure it out.

Savarin and JimFPU, thanks for your feedback. It helped. In fact I think it helped me understand why Julian Edgar chose to design in some camber-increase-in-cornering. It has to do with roll. When the trike rolls laterally during cornering, the pivot axis of course would roll with it. Since in my latest design the pivot axis is perpendicular (horizontally) to the boom, the wheels will always be oriented at 90 degrees (vertically) to the pivot axis.

Once again, I've hunched over pencil, ruler, triangles and protractor to produce yet another handy dandy illustration of what I'm trying to figure out. I've drawn three pictures in succession, all views from the front. In the first picture, you can see the front suspension in the nominal position. The pivot axis is level and the wheels are vertical.

But what happens when cornering? I believe I have worked out what happens in the second picture. As the trike tilts into the outside wheel, the pivot axis tilts (15 degrees for this illustration). Since the wheels are always 90 degrees to the pivot axis, this causes the wheels to tilt 15 degrees also. I think this is why an anti-roll bar is so critical to the suspension system, and why Edgar designed his trike with some compensating increased camber in cornering.

The third picture depicts what I think would happen when travelling a straight line while hitting a bump. Since there's no cornering roll, both front wheels remain vertical.

http://i59.photobucket.com/albums/g292/Locutus59/Workshop/img030.jpg?t=1229144594

Now I can already see a flaw in this reasoning. If you notice in the second picture, the body is rolling but I did not actually show the wheels turning. I'm not sure, but I think that with the wheels turned, the kingpin inclination may partially compensate for the tilting pivot axis, but not completely. So once again, I think Julian Edgar was way smarter than me with his design. He seems to have balanced everything out.

Another thing I'm wondering about has to do with the rear swingarm. One of the things Edgar mentioned in his articles was that the rear wheel has zero roll resistance, referring not to how the wheel rolls down the road, but to lateral roll in cornering. This is why he designed his rear swing arm as he did. he wanted it to have stiffness against lateral torque. So with this in the back of my mind, I went to Wally World today to look at suspension mountain bikes. The thing that stood out to me was that the only point of contact that the swing arm in a typical mountain bike has with any resistance to lateral torque is a two-inch wide bushed pivot where the swing arm connects to the rest of the frame. The shock absorber does not appear to provide much, if any, lateral torque stiffness. So I'm beginning to wonder if I should skip the department store bike swing arm, in favor of building a gorilla swing arm from scratch. Hmmm....

TheKid

12-13-2008, 02:31 AM

I'm basing my statements on what I interpret from the drawings, and making a model from paper tubes. Based on the angles in the drawings, both caster and camber will change on bumps. When it comes to suspension on a lightweight vehicle moving 30 mph, methods that "appear to be okay" could be disastrous. Even without suspension, Brad had a close call with the Streetfighter because the caster was excessive. It was corrected before the plans were offered for sale.
I stand by the tried and true philosophy, unless you can use a program like Truespace as Brad suggests, or you're able to make actual scale models, or you're willing to go through the mods needed to refine the design. (Which will probably be necessary even if you use computer or physical models, but fewer would be needed.) Once you have a prototype built after detailed analysis, testing can begin. I know of very few prototypes that didn't require tweaks at a minimum, or one or more major mods, after testing.
I find that even paper models of components help a lot, and are a good way of testing the best angles for the placement of springs and/or shocks.
For what it's worth: If I had done some more studying and corrected the trail on my Meridian, I may have saved myself from a busted leg, even with the boat seat. I thought I had mastered the effects of the wheel flop, which I thought was inherent with LWB bikes. Then at a slow speed, the front wheel hit a bump sideways, and I could not control the bike at all. I later dismantled the Meridian for parts, but kept the main boom and rear. My neighbor rebuilt the rest with proper trail, and the wheel flop was reduced drastically. It now resides at his summer home in Upstate NY.

savarin

12-13-2008, 10:32 AM

I'm basing my statements on what I interpret from the drawings, and making a model from paper tubes. Based on the angles in the drawings, both caster and camber will change on bumps.

My mistake, I was proposing something else entirely. I believe the correct name is double wishbone suspension or even unequal length, non parallel wishbone. Something like this http://www.ubuilditplans.com/SII2.html

And as for tried and true, a double wishbone is the preferred choice for performance vehicles because it doesnt alter caster and camber on bumps. But it does alter track width which leads to excessive tyre wear.
What I was after (and still am) was reasons why it wouldn't work for our creations rather than a blanket statement to that effect.
What exactly does not work in that configuration and will cause a problem in our vehicles.

Radical Brad

12-13-2008, 12:39 PM

Depending on the length difference between the top and bottom arms in a wishbone system, the track width may not be changed as the wheel moves up and down. A small top arm causes the wheel to camber slightly as it travels, keeping the center point constant. From what I understand, this is at the trade of inducing a less stable roll center. On an HPV, I would choose to reduce tire scrub, as this will certainly lead to rim fatigue over time.

I think wheel scrub is a serious concern when dealing with wire wheels. If I could not eliminate it completely, I would choose to ditch the frame suspension and add it to the seat and cargo area as a stand alone unit.

When you think about it, what is the real point of suspending the frame when it is only the rider or battery pack that needs it. Not much to damage on a simple square tube frame.

Brad

Locutus

12-13-2008, 01:05 PM

When you think about it, what is the real point of suspending the frame when it is only the rider or battery pack that needs it. Not much to damage on a simple square tube frame.

Brad

Brad,
I think it's a good idea to suspend the seat instead of the whole bike. Although it would increase unsprung weight somewhat, the frame may end up being stronger for the weight, and simpler to build. But so far I have seen no designs for suspended recumbent trike seating, and I don't know how to design one myself without some baseline ideas. Do you know of any suspended recument seat designs I can look at? I'm leaning toward mesh and frame seating but I'll consider other types.

TheKid

12-13-2008, 01:46 PM

A lot of us have said that before. It's much easier to design seat suspension, with the added benefits of having less parts to wear out. A well designed rigid frame could withstand shock, as well as save the wheels from damage, as evidenced by BMX riders.
After toying with suspension several times, I abandoned the idea because even a well designed suspension adds drawbacks that outweigh the advantages when used with a strictly HPV. With a powerful motor, the weight disadvantage of a double wishbone suspension is eliminated, or reduced to the point of being a non-issue, so that would be the way to go. However, it still has to be tested, and finding a design that works takes time and practice, especially if one is not proficient with mathematics and/or computer programs. An exception to the strictly HPV rule, may be a monocoque velomobile with inherent suspension, because keeping the weight of the vehicle under 50-75 lbs. is generally not a goal.
If your goal is to design a suspended vehicle, then do it, but get your education from people who have achieved that goal successfully, as well as studying the math involved. Part of that math includes allowing for the crown built into roads for water drainage. Since we ride on the extreme sides of the road in most cases, that means building the suspension to allow one wheel to be lower most of the time. One must also build the suspension to allow for dips as well as bumps. Suspension should be carefully designed to suit the type of terrain you'll be riding on most of the time. Four inches of travel is excessive, and very difficult to design safely. If you're going to ride on smooth roads most of the time, suspension is probably unnecessary, but 1 1/2" of travel is more than enough. Think about this when designing a vehicle - the suspensions of race cars on an oval track are vastly different from a passenger car . Mainly, they're designed with optimization for left turns.
If you want to build a vehicle and suspension would be a nice option, but not necessary, then seat suspension or no suspension at all are better choices.

Locutus

12-13-2008, 03:19 PM

It seems to me there were reasons discussed in this thread as to why modifications to the Street Fox design would be necessary for my intended purpose, that is, 30 mph cruise speed with electric assist. But I scanned through the posts and I couldn't find the specific reasons. Maybe I need to take a step back and assess what I really need to do in order to relatively safely pedal down the street at 30 mph. I think Brad said something about the Street Fox not being adequate (as designed) for such use.

Maybe I should be asking a different question. How about this: What are the simplest design mods that should be made to the Street Fox so that I can safely cruise at a steady 30 mph on varying terrain for 20 miles? Two easy mods I'll definitely do are to add the hub motor and change the braking to all-wheel disc.

Suspension? Is it really necessary? I'll be riding on well-maintained city streets.

Structural integrity? If the Street Fox (as designed) is in some way not up to the task, what specifically should be changed or beefed up to avoid a structural failure at speed?

TheKid

12-13-2008, 03:38 PM

Maybe some gussets added to the crossmember, or heavier guage steel? There are plenty of tadpoles that travel at 30 mph without motors, so the speed probably isn't as much an issue as the increased torque of a motor compared to human power. That's another variable that may need to be considered. You may want to look at other designs, specifically tadpoles designed for such speeds.

savarin

12-13-2008, 08:46 PM

just found this, I think it answers some of my queries. It looks as if negative camber change on bump is a good thing.

Dynamic Camber Gain

Car tyres work best when they are vertical to the road ie have zero camber. If the suspension maintains a constant camber in compression, when the car rolls (ie the outside suspension is compressed and the inner extended), there will be an effective camber loss of the more heavily loaded outside wheel during hard cornering.

For example, if the static camber is zero and the car rolls by 3 degrees, there will be a positive camber gain of 3 degrees of the outside wheel. It’s for this reason that the static camber is normally set negative (ie the wheels lean in at their tops), resulting in a vertical tyre when in full roll. However, using lots of static negative camber can cause straight-line tyre wear and instability under brakes. A better way is to use a suspension design that adds negative camber in bump.

An unequal length double wishbone suspension will cause the wheel to increase in camber (ie have a negative camber gain) when the suspension is compressed. This dynamic camber gain can be used to effectively offset most or all of the camber loss caused by body roll. For example, a suspension may be designed to add 1 degree of negative camber for every inch of bump.

TheKid

12-13-2008, 09:26 PM

Jack up the front end of a car, and you can see the camber is set. (Some designs call for negative camber, while others have positive camber)The wheels return to vertical once weight is put upon them. This allows the wheel to return to an almost vertical position whether you hit a bump or a dip, as well as compensating for uneven terrain, while keeping uneven tire wear at a minimum. The spindle and outer points of the controlarms generally have upper and lower pivot points allowing pivoting in all directions, in the form of ball joints. The inner connections of the control arms allow vertical pivots only, in the form of bushings. Depending on the design, either the upper control arm bushings and the lower ball joints, (GM RWD vehicles for instance) or the lower control arm bushings and the upper ball joints (Ford RWD vehicles for instance) are subject to the most wear. The double control arm suspensions in general superceded king pin suspensions, which were subject to bump steer. (Old Ford and International Harvester trucks manufactured through the 60's are good examples.) With double control arms, kingpin or spindle inclination was rendered unecessary through the use of unequal length control arms. Thus, wheels are kept as vertical as physically possible, allowing for minimal uneven tire wear and better handling. When tire wear is uneven, it's a sign that alignment is out of whack, and should be readjusted. The cause of alignment going out of kilter is caused by wear and tear on the bushings and ball joints, which also causes loose steering. Realignment and tightening of steering components will be possible until the parts wear to the point of needing replacement.

Radical Brad

12-13-2008, 09:34 PM

The StreetFox is plenty strong for what you plan to do, but the steering is not designed for that kind of constant speed. You can try it, but I know you will find it "twitchy" with the electric assist. USS wuth mechanical disadvantage is what you will need, but I think that will also need to be beefed up. The GreenSpeed style USS is very flimsy, so if you have to hard corner at speed, you are going to be holding on to what feels like a wet noodle.

I wish I had some ideas for you, but I am not going to be thinking about my new StreetFighter-II electric quad until next year. I do plan on trying something unique in the steering though.... something that will handle well at speed and give me a solid point to hold on to as I smoke around corners.

Brad

Locutus

12-13-2008, 10:43 PM

So it looks like the main issue is really the steering and braking. Makes me wonder how I got so wrapped up in the suspension. :rolleyes:

I still want a full suspension, eventually. But perhaps I should start with a stock Street Fox so that I can put one together quickly. Then I can have one while I'm experimenting with steering and suspension on a separate frame build. Then, when the suspension frame is just the way I want it, I can take the good components off the stock Street Fox frame and put them on the new frame.

Or not. I may just go ahead and build the full suspension frame first. I have time to decide. I don't even have the front wheels yet.

John Lewis

12-14-2008, 02:27 AM

Just to add some more thoughts have a look through this. Mainly the bits on suspension.

Bob Stewarts car-cycle x4. Think he used combination of seat and vehicle suspension.

http://microship.com/bobstuart/carcycletech.html

John Lewis

Locutus

12-18-2008, 05:19 PM

Okay, so I got to thinking about air suspension. Julian Edgar uses a complex air bag suspension in his Air Recumbent 150 design. So the cushion is air. Now, what if there were tires that were fat enough to give me sufficient cushion so as to eliminate the need for a front suspension under normal operating conditions, but that still had low rolling resistance and good cornering?

I may have found just such a tire. It's the Schwalbe Big Apple, and it's available in 20 x 2.00 or 20 x 2.35 sizes. There's a good review on it by Utah Trikes:

http://www.utahtrikes.com/ARTICLE-32.html

And here's a picture:

http://www.utahtrikes.com/uploads/utupgrades/38/picture1/bigapple.jpg

These tires are designed to optimize rolling resistance, comfort, handling and durability.

The 2.00 size would probably have less rolling resistance (30 to 70 PSI range), but the 2.35 size would give more cushion (20 to 55 PSI range). The larger size could absorb 2 inches of bump without risking a pinch flat.

Since the rear tire will be on a suspension swingarm, and will endure more wear due to both braking and drive traction, I'll probably go with the Schwalbe Marathon Plus on the rear, but for the front tires, the Big Apples look pretty good. Using these tires, I might be able to get away with the simpler non-suspended Street Fox frame design at my target cruise speed of 30 MPH.

I'm actually rather relieved at the prospect of perhaps not needing to build a front suspension. A standard Street Fox frame will be much easier and faster to build. I was starting to feel a little intimidated. After all, this will be my very first build. I can always build something more complicated later, after I get some experience with the first one.

My plans are beginning to take shape. I now have my rear suspension, I've selected my motor and battery pack, and have most of the other bike parts I need. I still have to order the Bitex hubs and disc brake system, find suitable axles, rims and spokes, and get the wheels built up.

Speaking of rims, what are your recommendations for 20" and 26" rims for tadpole trike use? I'll need some good quality, strong rims, probably in a deep-V style.

To get the target speed where I want it, I'm planning an innovation with the eZee motor. Normally they come built into wheels and paired with 36 volt battery packs to cruise up to 20 mph. There are two motors: one designed for use with a 26" rim, and a higher RPM version designed for use with a 20" rim. I plan to use a 48 volt battery pack and lace the higher RPM motor to a 26" rim. That will raise the top cruise speed to 30 or 32 MPH...right on target.

Here are the rear suspension, motor and NiCd 8 AH battery pack I'm planning to use. I showed the hubs and brakes in an earlier post:

http://i59.photobucket.com/albums/g292/Locutus59/Workshop/Bikes010.jpg?t=1229637502

http://www.ebikes.ca/store/images/Ezee_Kit.jpg

http://www.ebikes.ca/store/photos/B4808CdR2-EL.jpg

Locutus

12-19-2008, 06:37 PM

I'm probably going to do my first build without front suspension, but I keep coming up with new suspension ideas. What do you think of this one? It only requires one shock absorber, but would only work if the pivot axes are parallel to the boom. the top tubes could come from the top frame tubes of road bikes, and the bottom tubes could be made from seat stays. This design would require use of either two head tubes or two bushed tubes for the pivots, in addition to those used for the kingpins. Each arm would have four triangles, making it very strong. See if you can spot all four triangles in each arm. Here's my crude sketch:

http://i59.photobucket.com/albums/g292/Locutus59/Workshop/img033.jpg?t=1229728714

If I wanted to angle the arms forward, I'd need two shock absorbers which would have to meet at a fitting on the boom, and the two arms would no longer be directly connected by the shock. I'd also have to change the pivot axes.

Radical Brad

12-19-2008, 09:00 PM

Locutus

12-19-2008, 10:33 PM

Your last suspension system would not work.

The main problem is that the main frame boom and rear wheel would simply flop to one side as there is nothing to keep it straight. On a quad, where the two rear wheels stabalize the rear, it would work, but suffer greatly from front wheel skid.

To fix that design, you would need 2 shocks connected to a central point on the boom to keep it from flopping over to one side. I still think wheel drag wil be way too much though.

Brad

Yeah, I thought of that after looking at the picture for a while. What do you mean by wheel drag in this case? And what precisely would be causing it?

How about this variation on the same theme?:

http://i59.photobucket.com/albums/g292/Locutus59/Workshop/img034.jpg?t=1229743777

This version could be angled forward since there are two shocks. the pivots would have to be perpendicular to the forward angle.