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

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Springs. They have crossed my path many times. You only have a few choices:

#1. Buy what you need - if you can find or afford it,
#2. Make your own (small) from piano wire, guitar strings, or such - see: https://www.instructables.com/id/How-to-Make-Springs/
#3. Use some other existing springy material - elastomer, fibreglass, titanium, etc.,
#4. Get someone to make what you want for you, or
#5. Make your own from scratch through hardening, and then tempering steel.

Can you do #5 yourself? Many things on the Internet say you can - or someone can do it for you. It requires heating mild steel to a critical temperature (check by colour or lack of magnetic attraction) and then plunge it into warm oil - see:
for one video. It is something I have never tried, but have only thought about when I needed something different. I usually end up changing the design and the need goes away. Would be ideal for making a transverse leaf for front suspension.

Anybody fiddled with making their own springs using #5?
 
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Kevin - VK3CKC

Life is to short for building springs
 
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Ok suspension on hold whilst I either source a 350lb rear shocker , try DIY with valve springs or find another solution...

Still busy with rear fairing [ needed more than springs at present ]



Current Python separated and rear end weighed...



Seems rear end weighs about 14kg.

So idea is to remove all surplus metal work and added wooden tail box.

I had a brain wave and realised if I made the pannier rack free standing and bolt-able to the frame I can still run it in this configuration sans tail box if I want so that is the plan.

As I need some points to bolt the tail box down anyway I will put then in a suitable place for the pannier rack as well.

Wow forward planning ? what next ...

ps look at the abuse the blue paintwork has taken , that has been on about 7 months and 870 miles

under seat.



marks are where I am contemplating raising seat as high as possible and then welding seat brackets to main frame [ fed up with building my trikes for others !]
that way I can get rid of the bolts and cut out the tubing between the brackets under the seat and save some more weight ?
 
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Ebay is a wicked mistress ...

Wondered if this may be of use to me ?

hoverkart rear suspension ?





£55 squid delivered to a store near me ?
 
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A pity they don't say what their ratings are. I would imagine they would probably do. Virtually any of that type should do provided they were mounted where they got sufficient compression force to make them work. It is all in the angles.

If you want to play around with finding out about such things, see: https://www.bbc.co.uk/bitesize/guides/zttfyrd/revision/6
 
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A pity they don't say what their ratings are. I would imagine they would probably do. Virtually any of that type should do provided they were mounted where they got sufficient compression force to make them work. It is all in the angles.
Lucking out with bicycle parts I decided to spread the net a little wider as a go kart does similar stuff and some of them have suspension.

Second look at it and I would be gambling on the springs being 350lb or less and throwing the rest way as there are no bearings in it at all

If you want to play around with finding out about such things, see: https://www.bbc.co.uk/bitesize/guides/zttfyrd/revision/6
Thanks will look into it.

This looks more promising and only £9 with a 200lb spring

https://www.ebay.co.uk/itm/Gokart-Rear-Suspension-Shock-Absorber-Black-185mm-200lb-Kids-Mini-Go-Kart-/174094760903?hash=item2888db3bc7



It says ' There is no spring or rebound adjustment on this shock ' wonder if it is worth paying a little more and getting that ?
 
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Details say no spring tension adjustment and appears to be no adjustment at all. A simple bicycle "shock" has preload ability. That means that it can be screwed up to a point where there is no suspension movement until the setting is exceeded. That should prevent cornering lean to a degree if that concerns you. A straight spring only would provide floating suspension which would be a little marshmallowy.

My Warrior modification has an 850lb simple bike shock with preload. It was fine until I loaded up the rear rack and then the rear wheel easily ran out of clearance. The first time I rode it, it was really hard pushing as the tyre rubbed on the rack full time and I didn't notice until the return trip. The mechanism was a short vertical shaft near the suspension pivot and the front of the shock hanging down at about 45 degrees. Lifting it up to about 35 degrees below horizontal made a heck of a difference. In short, the force applied to the spring for suspension action can be lowered by changing the applied leverage by changing the positioning of the shock to give more (softer ride), or less (harder ride), leverage. Easy. I really see no problem with using simple bike shocks.
 
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Stormbird: There is nothing worse than ordering something unknown and finding out that it is not suitable. You could always grab a shock that is ready to hand, weld up some rough upside-down faux suspension setup that you can stand on and play around with various positioning and angling or, like bikes, have an adjustment so you can play with it. You could then jump up and down on it until you think it is acceptable. Don't forget to consider that with one on each side of the trike has to cater for half the weight each.

In any case, bicycle shocks are usually rated in lbs per inch of compression which, I guess, means it takes more and more force to compress them beyond 1". I have half a dozen or more shocks from random donor bikes, all of which are 850lbs/inch except one, and that one is 750lbs/inch. They can all be used for trikes - provided the mounting angles, etc., are somewhere near. Suck it and see usually works for me.

Have you managed to sort out how to use whatever shocks you end up with?
 
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Stormbird: You could always grab a shock that is ready to hand, weld up some rough upside-down faux suspension setup that you can stand on and play around with various positioning and angling or, like bikes, have an adjustment so you can play with it. You could then jump up and down on it until you think it is acceptable. Don't forget to consider that with one on each side of the trike has to cater for half the weight each.
Yes it is my intention , however knowledgeable folk on here [ like you ] could potentially stop me going full speed down known dead ends ?

I have half a dozen or more shocks from random donor bikes, all of which are 850lbs/inch except one, and that one is 750lbs/inch.
I have from 350lb in 50lb increments all the way up to 850lb's however almost all are in the singular , and I want IRS :D

provided the mounting angles, etc., are somewhere near
It's the change in angle and what it brings to the party that causes me the most confusion ...

Also the shocks shown above are 200lb which may be needed , never seen them on a bike.



what I want is half of this ! a 2CV , so trailing arm and horizontal spring along side chassis.



Crude redrawn sorry , however can you see that the chassis can effectively end at the trailing arm pivot and there are no chassis members having to go rearwards to above the wheel i.e McPherson strut or vertical spring element at wheel end of trailing arm ?
 
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That would work and would require a fairly hard spring due to the leverage. You have a lot of wheel movement for little spring compression hence the need for a hard (ish) one.

One of the reasons I spend a little on air shocks is that they can be set to any rate. It's all very well making a nice set-up but it's no good over or under springing it. It needs to be right. I'll be honest and say the proper damping that such units give is probably wasted on me and only of use on a downhill trail with 8" of rear wheel movement when going at full chat but the ability to set the spring rate is certainly useful.
 
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Personally, I have no need for lining someone else's pockets for the sake of such jiggerypokery. Using an 850lb simple MTB shock on the rear of my Warrior, I can ride over 4" logs and virtually not feel it - provided it is only the rear wheel that rides over it.

There are some who say that suspension is not required on a trike. Might be so if you only ride on smooth pavement. However, having SOME give for off rode is a bonus, especially for a tadpole where you mainly feel bumps in the rear. The front wheels just vibrate, annoying but a little easier to accept than a bumpy rear that jars your back. I'm not sorry I fitted suspension to the rear of my Warrior.

Stormbird: Have you worked out the mass of what you expect the rear wheels to carry?
 
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If you use suspension components in a similar way to how they are intended (ie use a rear triangle or swing arm whole) then I agree you don't need anything fancy. Here the suspension will probably be custom tailored to the space available and chassis design and crucially lean against that suspension must be considered making getting it right much more difficult and important than something that can't lean (assuming more than two wheels here). This always throws up compromises and where one person sees the compromise line is not where another will see it. Neither will be right or wrong, it's just personal choice. I recommend air springs for the ability to explore and set such a compromise not because of any superior suspending they will give. Indeed the pair I linked won't give any superior suspending at all as they're just undamped springs of infinitely variable rate.

A case in point would be my leaning trike. The suspension and steering are full of compromises that get worse the more it leans, steers or suspends. I started off with soft suspension but very quickly moved to hard to limit some of them. I only had hard or soft options so could not explore any points in between. There's nothing stopping me from going back and swapping to air shocks to sort it out. I'm simply saying I should have anticipated such compromises would require choice at the start.
 
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That would work and would require a fairly hard spring due to the leverage. You have a lot of wheel movement for little spring compression hence the need for a hard (ish) one.
The blue rear end has the mainframe sitting 5"of the floor and the seat about 8" the frame goes to the rear and the rear wheels are mounted on risers:-



now if I go to trailing arms they will be 10" off the floor due to 20" wheels and if I assume the trailing arm is parallel to the floor and 10" long the pivot point would probably be in line with the rear seat mount ?

Now I only showed a parallel shock point in the drawing as that is what I am familiar with on a 2cv , to be honest as long as the shock is forward of the rear axle and parallel to the plan view of the trailing arm it could be mounted any angle up to 45' without incurring excessive frame material and hard to triangulate tubing ?

Part of the development is to raise the trike AND me , out of the dirt and maybe even to 26" wheels , however not at the expense of it's cornering ability which currently gives little cause for concern :)


[ QUOTE]One of the reasons I spend a little on air shocks is that they can be set to any rate. It's all very well making a nice set-up but it's no good over or under springing it. It needs to be right. I'll be honest and say the proper damping that such units give is probably wasted on me and only of use on a downhill trail with 8" of rear wheel movement when going at full chat but the ability to set the spring rate is certainly useful.[/QUOTE]

Maybe something for me to think about in the future ?
 
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Stormbird: Have you worked out the mass of what you expect the rear wheels to carry?
Not yet as the plan to build a rear faring will increase the weight as will carry the full camping gear load.
Am prepared to lock out the suspension when travelling with fairing and camping gear if this makes it better overall as that is only 2 weeks of the year.
 
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Not yet as the plan to build a rear faring will increase the weight as will carry the full camping gear load.
Am prepared to lock out the suspension when travelling with fairing and camping gear if this makes it better overall as that is only 2 weeks of the year.
Will this fairing have all the aerodynamic characteristics of a brick (like my car... 2 house-bricks in mating formation)? Will you be undertaking wind-tunnel testing and slipstream analysis? The world needs to know.
 
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Not yet as the plan to build a rear faring will increase the weight as will carry the full camping gear load.
Am prepared to lock out the suspension when travelling with fairing and camping gear if this makes it better overall as that is only 2 weeks of the year.
Clarke if you spent less time looking out the window and picking your nose ?

You would know that I am attempting to build this on my Python trike :-



I am starting with building the rear part so I can have wheel arches and stay clean and dry ....



then on to the front part ?

Currently trike is in pieces whilst some of it's less desirable foibles are ground and welded out and rear rack is removed to allow box construction to begin....

Pictures to follow shortly 4 pieces made 2 more to go then on to the welding..

It is amazing the rust I have found on the frame bearing in mind it was only made and painted in May of this year.

I suppose the ' more ' frame you have the more rust you can collect (y)
 
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