My life with Python trikes Mk1 , Mk1.5 , Mk2 ?

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There are places where weight can be avoided and places where it can not. The clamping set-up you point out is a complex dual axis pivot relying on the friction of the clamps for fundamental integrity. As such the clamps need a large surface area and need to be substantial to generate enough friction. I could not find a lighter system I could make that would work without completely sealing the thrust bearing in so to make it unserviceable. If you could devise a lighter system please tell me. I do not purport to have any monopoly on the best ideas.

By contrast mounting a backplate is a much simpler task with no moving parts, where a 40x20 ish box section with a pair of reinforced holes would both be stronger and much lighter than bar. Bar has many great uses in bracketry etc but is rarely the best choice for larger pieces of chassis, though I very much understand we often use what we have rather than what is best. In my case I deliberately added weighty bits by reasoned choice here as I could not conceive of a better system. I have, on other occasions, used poorer solutions because I had them already.

If we were weight weenies none of us would use trikes but making something unnecessarily heavy has no benefit and ought to be avoided where you have the choice. Swapping bar for box is simple, lighter and stronger.
All very true Popshot. I just use what I have to hand and it works and It has served me well. I could use thinner metal it is true; but I am OK and happy in the knowledge that it won't bent under load or snap off at a critical moment, nor will my backplates go for a spin when I hit the anchors. While a hollow section and an inserted crush-tube would save some weight it isn't my top priority because I weigh about 4 times the weight of the trike. :D
 
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Ok lots done today.

The Mk3 has always been knock kneed and hard to ride , so as I had it to investigate the broken brake tab I decided to try and fix the appalling wheel geometry.



So this is the rear dead axle with the good side downwards , a M12 rod through from the good side appears to be parallel to the frame all the way to ' bad ' axle block. The masking tape is where a M12 rod stops when inserted from the bad axle block . DannyC imparted some engineering voodoo from the late Sandman [ aka John Price ] about welding the side you want to move a few times and the shrinkage will correct the mis-alignment.

Sadly I promptly ignored that and carefully hack-sawed down three sides of the axle block , I then squeezed it as tight as I could with a clamp.



Now I could drop the rod down from the top and it would go through the lower hole , if not I would have attached it with the saw again till it did !

So I have now welded that on 3 sides and it looks much better , I will know more when I get both wheels on and can measure between the rims.

next up rear rack for the Tilt#4 ?



Currently tied at the top and bolted at the bottom , the unpainted tube will be trimmed to fit under the piece it is up against to pick up a bolt hole there.



The bottom mount came from my very first Python via Tilt#3 , so it is bolted through some 8mm anti-crush tubes as can be seen it is slightly narrower than the rack and at the moment the rack has been drilled out to M6 however the bracket holes are M8 this may need fixing.



This is the front support , tacked to a 3mm foot and needing trimming at the top with another small plate with mounting hole welded to it.

I have goofed as the rack is right up against the seat back , i think I have got the BB to seat length correct as the rack currently stops the seat traveling rewards I may have to rethink the mounts before drilling more holes in the frame to mount the rack ?

Paul
 
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The forum is doing the thumnail thing again or rather it's affecting this thread only so presumably it's the picture hoster.
 
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So decided to bite the bullet and make some brake back plate mounts , I remember now why I have 4 different designs and I am not please with any of them.

Now the whole design is very poor no access , almost no clearance parts at difference distances from back plate etc ,



Although Sturmey Archer supply a spacer [ shiny bit in middle ] it does not space it far enough away from a flat surface for operation arm clearance [ on the left ] neither does the spacer and the clamp plate on the right end up the same distance from the flat surface.

First thing was to make up a spacer so I can bolt the back plate on it it's position without needed the wheel , which of course is always in the way.

Cut some 3mm angle drilled it for mounting hole , bolt it to back plate and firmly clamped it to frame , there was just room for 1 weld before I had to remove the back plate for access.
Then got 3 more welds on each one and we were in business ?



look at the back plate lock bolt head almost impossible to reach between between the wheel and the back plate/frame and from the front only a hex head will allow tightening from between the spokes [ still not easy ! ]

So yesterday I got the rear wheels on and they spin nice and are much straighter , this morning added the front end and came to cable the brakes when the adjusters won't fit in their slots...



Can you see why grrrrrrrrrrrrrrrrrrr , god this is a POOR design.

Whole thing has got to come apart AGAIN and the grinder deployed.

Paul
 
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Moan, moan, moan. ;)
I am addicted to SA drum brakes on my trikes but I hate them. Chunter, Chunter, Chunter. :D
You know full well that you prefer them to disc brakes and wouldn't swap the drums for discs at any price. :p
 
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Well stuff has happened ?

Tilt#3 has had it's wheels re-aligned now almost passable , one has slight positive camber , I can live with that the constant tyre scrubbing noise has gone so maybe it will be a bit sprightlier and cut down the to mums time by a few minutes ? the re-done brake anti turn mountings with lock nuts holding the back plate tight to the mount seem to work.

So we will find out tomorrow if all is well :LOL:

Thanks to Maddox [ of this parish ] the Sachs 2x6 from German Ebay for the Flevo has arrived , after much sweating/grunting & struggling I have it dissected ...



So upper are the brake parts from the non-cassette end threaded on some M8 rod.

The part in front takes the cassette on the left and hopefully will replace my broken part as a unit without taking the 2 speed apart.



As it all looks very good still with grease and no sign of water ingress , NOR broken parts 👍:LOL:



It is not terribly complicated to be honest 2 circlips either side of the spring on the right and couple round springs for the 2 sets of pawls inside and outside , however at this stage I do not want to damage the circlips and as I only want to do a couple hundred learning miles on it then it will suffice.

Reassembly however is not straight forward ...

The back plates are different and the Flevo has mountings that will only match the back plate it came with I think.

The inner cones are different sizes the wshers & lock nuts are different thicknesses and the back plates are different where one has a more pronounced bulge to accommodate the larger inner cone.

I need to juggle the cone/spacing washers and lock nut that will give a combination where the back plate covers the outside [ it has a lip on it ] and also does not bind when the wheel turns.

all for now Paul
 
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Hi all

Tilter #3 = 124 miles added to Tilter #2 & 72 miles that is now 196 Tilting miles.

Found out I can ride it no hands for short distances , picked a 1/4 mile stretch with rain run off camber and 8ft pavement slight up hill [ all things in my favour ] got it going and gingerly put my hands on my stomach.
Couple of controllable wobbles and a slight meander covered the whole 1/4 mile without drama

Out on it Sunday for a social so should pass 200 miles , breakfast and show and tell , may even find a couple of punters to try it ? we can live in hope.

Paul
 
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Tilter #3 = 136 miles

Sunday ! social ride !!! taste of the old times ....



So this is the start at South Clifton , and no I did not hit the Sewage Pump sign it was like that when I got there !

I had to problems on the ride , neither to do with the tilting and both to do with the prototype nature of the trike.

problem #1
I set the wheelbase @40" should have been exactly the same as my Holland Python and it should have fit in the car , although i do have to raise the rear of the trike on a crate to close the back door.
It would not close after some cursing and shuffling I eventually was able to slam the door and it stayed shut , as a precaution I fastened a piece of wood to the tow-bar overlapping the door in-case it sprung open on a bumpy road. When I got the trike out it had skewed the rear axle on the spine , I did not have the tools I needed to fix that as it is poorly designed and needs socket sets and box spanners to get access to the bolts/nuts,I did the best I could by wedging the nuts with screwdrivers and using spanners that would only turn about 10' at a time.

We were cycling down to a rail track cycle path we use a couple of times a year to ride to Lincoln however I had never joined it at this point always further away and rode the rail track to meet my friend at this point.
IT WAS A NIGHTMARE !!!



there was over 1/2 a mile of nettles before we reached the railway , I had shorts on and had removed my sweatshirt before we set off ! as you can see it was also to narrow for a trike with 30" track.
On the normal Python I would have put my arms in the air and steered with my feet , I cannot do that yet on this trike.

After much cursing and screaming I reached the railway , there was plenty of old ' stuff ' about made more interesting as it was a old passenger line and not an old coal line as most of the cycle routes are where I live



You can see the ' funny ' sort of trike my friend rides , that is actually single speed however it does have a diff ! the track is about 24" and seat usual bike height so to get them around corners you have to hang your a**e over the inside wheel !

Like this
most undignified for men of a certain age ?



Moi with both bikes taking a ' comfort ' stop at a MTB trail start point board , odd really as it also attracts horse riders and they don't mix with MTB's very well ;)

Second breakfast at the cafe attached to the Giant cycle shop Doddington Hall , another pot of tea and a big bun with a cherry on and we were ready for the journey back.



Picked up another soul for some of the return journey and it was noticeable I could not keep up with them despite there speed only being about 10mph , I had been plagued by a squeak on the way there so when they stopped to natter and part there ways I had an investigation.

problem #2
because the front end swings quite a way it needs large loops in the brake cables for this , due to how low #3 is to the ground I had tied them to the frame to stop them dragging on the floor , I had done them up a little to tightly . When I turned left it tightened the right brake cable enough for the outer end cap to pull out of the right the brake adjuster cup and did not go back in when the slack returned so effectively pulling the brake half on.
Remove one of the straps and re-seated it and no more problems and a good 1mph gained ! that was a relief.

In preparation for the dreaded nettles I donned my sweat shirt , pulled my socks up and used my hat to protect my right hand and went through them as quickly as I could.

So another 12 miles [ spooky that ] and no surprises in the handling department , although at 100+ miles it seems it is still not fully sorted still the prototypes are getting better #4 does not have the bolt on rear and is higher so hopefully won't suffer from the same cable problems.

all for now Paul
 
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Tilter #3 = 148 miles

Engine did not have it's heart in it really today , cold head wind no sun etc etc

trike did as advertised on the tin ?

Did some Pythoning
................Tilting
................Got me there
................Got me back

Paul
 
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Tilt#4 has had the brakes tinkered with and cabled up , they do work ok.



However I am very concerned about the screw up with the pedal height ?

As can be seen in this shot the seat is @ 18" the pedals are at about 15" I want them between :-

Level with the seat - so raising 3"
or
5" higher than the seat - so raising 8"

This is not going to be easy on an already hacked at both ends frame , there are dire warnings from DannyC of lack of chain wrap if I just notch the frame between the pivot and the axle ?

You might say , stop messing about build a new front end ?

Well that is my intention , however I also want to build a new pivot at the same time which means a lot of work and it off the road where I want to ride it and see if it is heading in the right direction ?

DannyC get your paper and pencil out I would like to discuss this tomorrow :giggle:

Paul
 
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Paul,
I fixed my lack of chainwrap and the chain-skipping issue caused when I cranked my frame to get the BB higher by relocating the chain-tensioning derailleur to ensure >50% engagement with the sprocket.
I suspect you will struggle a little to keep the same inseam measurement AND crank the BB up without incurring chain-to-frame interference unless you can move your seat fore & aft.
Chat tomorrow. :)
 
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If you notch the frame behind the axle and derailleur mount the wrap will stay the same but you'll lower the front as the axle will move up. If you notch it ahead of the axle the derailleur will likely need moving plus possible frame / chain issues. Either way will pivot the bottom bracket towards the seat altering the leg reach unless you also lengthen it ahead of the axle meaning a cut rather than a notch.

With the seat now so high there's plenty of room for a bigger drive wheel if you want.
 
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If you notch the frame behind the axle and derailleur mount the wrap will stay the same but you'll lower the front as the axle will move up. If you notch it ahead of the axle the derailleur will likely need moving plus possible frame / chain issues. Either way will pivot the bottom bracket towards the seat altering the leg reach unless you also lengthen it ahead of the axle meaning a cut rather than a notch.
You are right , the conclusion of this mornings brainstorm was.
It has been cut about to much already
Any attempt at cutting will throw a different parameter out , each one harder to correct and needing more work
So 2 solutions are possible
Both involve ' adding ' another BB in the right place above the existing one.
This solution will be EXTREMELY ugly however is a quick fix to get it on the road.
Whilst a new front end is designed

With the seat now so high there's plenty of room for a bigger drive wheel if you want.
You are a very naughty boy ....

Paul
 
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You are right , the conclusion of this mornings brainstorm was.
It has been cut about to much already
Any attempt at cutting will throw a different parameter out , each one harder to correct and needing more work
So 2 solutions are possible
Both involve ' adding ' another BB in the right place above the existing one.
This solution will be EXTREMELY ugly however is a quick fix to get it on the road.
Whilst a new front end is designed



You are a very naughty boy ....

Paul
Yes, a Nice 24" wheel with a lovely Nuvinci hub in it will look splendid.
You will have fewer chain/frame interference issue than with a cassette cluster.
Sorted! Well done!
 
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So mockups of 2 possible solutions to raising the BB on Tilt#4 and a unlikely start to the new build front end ?

DannyC's idea , I think :whistle:



I trimmed off the red painted dropout's to get them closer to the main frame so they could be weld to it.
The existing front mech post could be used with a handle bar stem with the goose neck removed and bolted through a 3mm plate welded to the chain stays [ that may be enough to hold it in place ? ]
The seat stays could then be removed and the dumpy seat post cut down on the straight bit , it may work ?

My idea:-



add another BB on top of the front mech post , as can be seen that moves the BB back much to far , so I cut the mech post and tried to get it vertical [ almost succeeded ].
So I would sleeve the inside of the upper BB join with a fork stem , that leaves the mess of the notch cut in the original mech post and adding 2 additional stays from the new BB to the frame in front of the axle ?
Oh look it now looks like DannyC's solution , that was probably easier to implement in the first place?
Answers on a post card please to the usual address ?

I was hoping this would provide the basis for a whole new front end as as you can see the existing pivot is a really mess and not engineeringly sound :giggle:



It was to be my FlevoTrike copy , halted when I bought a real one.
Ain't the answer either , yes it gets the pedals higher , however they are now much to close to the wheel and so when lined up with the existing pedals the pivot is feet from it's actual position on the rear end.

More thinking needed me think's paul
 
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Tilter #3 = 160 miles

Engine did not have it's heart in it really today again (n), slight head wind no sun etc etc

trike did as advertised on the tin ?

Did some Pythoning
................Tilting
................Got me there
On the return I picked up a thorn , bummer , of course only happens on a day when I am in a hurry.
Still the escape of air was not to serious and I only had to stop 3 times to pump it up , faster than changing the inner tube even thought it was on a rear wheel
................Got me back

Paul

Update it was a thorn however tyre may have survived it 😥if constant scrubbing due to mis-aligned tracking had not rubbed them through to the canvas ;)
 
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Ok so trying solution 3 really just 1 & 2 mashed together with a touch of adjustable thrown in for good measure ?



hacked the front mech mount off - it was only confusing matters - cleaned up the 3mm ' V ' gusset and welded some 1.25sq tube on , nice fit for a upside down seat tube complete with BB.
Currently the 2 BB's are 12" apart , bit excessive I probably need between 5" and 8" however seat tube can slide in and out of 1.25" square and both can be trimmed , probably hold them together with 2 M8 bolts @ 90' to each other ?



It is not quite square in this view , it's a welding thing ! small tacks on 2 faces and the right hand side in this picture has a full length weld so pulling it over a bit.
hopefully that will correct itself when fully welded.



purple seat stays just dropped on to see what fit is like , looks quite good so they may end up on there when height of 1.25" sq decided ?

Paul
 
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Ok so trying solution 3 really just 1 & 2 mashed together with a touch of adjustable thrown in for good measure ?



hacked the front mech mount off - it was only confusing matters - cleaned up the 3mm ' V ' gusset and welded some 1.25sq tube on , nice fit for a upside down seat tube complete with BB.
Currently the 2 BB's are 12" apart , bit excessive I probably need between 5" and 8" however seat tube can slide in and out of 1.25" square and both can be trimmed , probably hold them together with 2 M8 bolts @ 90' to each other ?



It is not quite square in this view , it's a welding thing ! small tacks on 2 faces and the right hand side in this picture has a full length weld so pulling it over a bit.
hopefully that will correct itself when fully welded.



purple seat stays just dropped on to see what fit is like , looks quite good so they may end up on there when height of 1.25" sq decided ?

Paul
You are making great progress Paul, I hope to get my welder back this week and I will get back into the game. :)
 
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