Tilting suspension Flevotrike ? - Can this really do what it says on the tin ?

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Hi all

Can this really work , surely the pivot links to the cross beam can't also be the suspension medium ?


Can it really be that simple ?

What initiates tilting ?

regards Paul
 
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Hi Paul,
Looking at it in that clip, I would say Yes, and Yes to your 2 questions.
The links and cross-beam do all that is required. Tilting will occur naturally when required, initiated by the usual forces that make a 2-wheeler tilt when going round corners rapidly.
All things being equal, (especially the resistance of the 2 suspension springs) then the bike will sit upright in a straight-line. Note this is especially true IF the rear wheels are locked by the brakes, then the trailing arms do not move freely. However, un-braked it is free to topple in either direction, you could put a damper on it, of course.
So sitting at a stop should be pretty solid and only the first few feet/yards might be a bit wobbly I would think.
This focus/fascination on suspension & tilting makes me think you are keen to address an issue you are experiencing on the Python "spine-shaker" as it is today.
If you stick with the Python FWD, this would be much easier to make than the "Longabike" style RWD delta trike.
 
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Hi Paul,
Looking at it in that clip, I would say Yes, and Yes to your 2 questions.
The links and cross-beam do all that is required. Tilting will occur naturally when required, initiated by the usual forces that make a 2-wheeler tilt when going round corners rapidly.
It's the links I am questioning ? surely they are to ensure when one wheel goes down the other if forced up ?

In this example does this force not get absorbed by the spring and not get transmitted to the other wheel ?

The Mk1 Python is 1.5" sq frame very short wheel base and so has a harsh ride with a solid seat and little cushioning provided by the ventist seat pad.

The Mk2 has a greater wheel base and being only 1.25" sq main frame has a more flex in it ? however still with a solid seat and little cushioning provided by the ventist seat pad.

So there is room for improvement ?

Unsure whether I really need tilting [ see below ] seems in some scenarios it comes as part of the package ?

If you stick with the Python FWD, this would be much easier to make than the "Longabike" style RWD delta trike.
Swings and roundabouts ?

Python is shorter but bends in the middle , only a problem if trying to give it a body.

Longabike will be .. well longer however it should be manoeuvrable enough for me and easier to add a body.

I want to be higher and so tilting maybe the only way to achieve that and still have a safe ride ?
 
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SirJoey

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Looks amazing! Probably a lotta fun to ride,
but would take some getting used to, I would think. :unsure:
***
 
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Looks amazing! Probably a lotta fun to ride,
but would take some getting used to, I would think. :unsure:
We will find out in due course .... as they say watch this space...

A lot of the people are banging on about tilt locks and other ' dubious additions ' ?

I think this is probably prompted by people who mainly ride recumbent trikes ?

I am HOPING that also being able to ride a recumbent 2 wheeler I won't miss/need a tilt lock ?

here is a tilter TT conversion

and he had this to say about it :-

How the trike works:
When the tilt is locked, it steers like a tricycle or car: if you want to go left, you turn left. When the tilt is unlocked, it steers like a bicycle or motorcycle: when you want to go left, you turn right to initiate the tilt.
I lock the tilt when stopping so I don’t need to put my feet down (goal was to build a streamliner; I wouldn’t be able to put my feet down). At this point it goes from steering like a bicycle to steering like a tricycle. When I launch, I go straight until I get to balance speed, then unlock the tilt. At this point it goes from steering like a tricycle to steering like a bicycle.

The perceived advantage I saw for using a disc brake for the tilt-lock was that it would positively unlock and I could stop with the trike level on a non-level surface.I lock the tilt at 5 mph or less. If it failed (locked) at speed it would be a dirty crash. Imagine 25 mph on your bicycle and the steering reverses. It also must positively unlock. The chances of a pin being wedged are high.

After 140 miles on the bare trike, I abandoned the project. The tilter worked well, but it did not give the absolute stability I have become used to with the fixed axle.I liked the tilter’s narrow track for riding on the shoulder or getting through doorways.


So all is not sweetness and light in the tilting world !
 
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The top crossbeam at the rear is probably attached to the main frame via a rubber block (you can see it move in relation to the main frame) and I would hope some sort of lateral (along the line of the main frame) pivot too to make a limited travel pivoting, resisting and self centring joint like this:-



This type of joint allows a degree of pivoting and up/down suspension whilst only allowing a limited left/right movement in the case of the trike.

Imagine the right is the front of the bike and the two arms on the left are the top crossbeam in the video.

As the trike tilts the bottom crossbeam follows the trike being a solid mount. That pushes and pulls on the suspension units as one wheel rises and the other lowers. This in turn pulls and pushes on the top crossbeam which being rubber mounted has a limited amount of give to the main frame. The more it tilts the more the rubber has to give and the size and hardness of the rubber has to allow the trike to tilt to it's maximum expected lean. If the trike tilts beyond the rubber's ability to give the outside wheel is in danger of leaving the ground because the top crossbeam would be pulling the suspension unit and instead of tilting around the centre the trike is going to act like a bike around the front and inside rear. It'll probably only do this for a fraction of a second before punting the rider off! Whether the inside wheel does lift at that point or not also depends on the travel and pre-load of the suspension units. The two are very inter-dependant - ie if the rubber runs out of give at high lean a soft suspension may well take up the slack. A hard suspension may not. I suspect I'm being overly critical of a potential weakness as in reality I'd expect not to reach such a possibility as any normally set up suspension units ought to supply enough travel and only units set up for a very heavy loading would be at risk of such a scenario. The ideal is very long travel units with little pre-load designed to reach the desired ride height with the rider aboard.
A hard rubber will give the trike the ability to ride more like a non-tilter with little input from the rider to stay balanced at low speed whilst a soft rubber will mean the rider putting a lot more effort to keep balanced, again at low speed, like a two wheeler. A hard rubber will make high speed cornering more work and a soft one will make high speed cornering more natural (if you can call a flevo natural at all!). The suspension units act only as suspension units for the wheel they are attached to. The rubber block also adds to the suspension to a smaller degree but acts equally on both wheels. The rubber block ought to keep the trike at least reasonably upright when parked too and imparts a desire to always return to the upright state when tilted.

An ingenious system if you can get the size and hardness of the rubber correct. Such a rear suspension should work with any type of delta. I'm very impressed.
 
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A Duschar joint ?

however I am not convinced that the white trike has one ?

 
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Yes.
The top white crossbeam definitely has some give relative to the main chassis. It appears that the white bit that bolts to the chassis has the rubber between it's U section on top and the box section underneath it. On tilting the suspension units themselves barely compress or extend. The bulk of the difference from the wheels raising or lowering is taken up by the give in the top crossbeam.
 
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Look at the intersection of the line to the main black chassis. I know there's the matter of the camera angle but it clearly shows the beam at different angles to the main chassis. Also look at the differences in the top beam to the lower.



 
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There used to be videos of this on Youtube , now sadly gone :-


Almost the same but no suspension :-



This is similar also
 
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Ok found what I was after - you know when you have that gut feeling somewhere on the net is the idea you are looking for ?



From here :- Solar tilting trike


So in my view it is :-

A wrapped version of iLean where both wheels are parallel and not staggered.
A more compact version of the white suspended tilter show above [ but without suspension ]
Could have suspension added if short tie rods changed for springs ?

So for me it is to narrow and has big wheels [ although they maybe in my future ?]

It is easy to see how such a compact mechanism could fit on the Python under the seat ?



The area between the cable tie on the main frame and the vertical pannier rack support previously housed the bottle cages and tent so both easily re-positioned , as can be seen the bulk of the luggage is housed just behind the axles and despite all the doom sayers have not cause any traction issues.

So ideally the unit wants to be narrower than the 30" the existing rear wheels are , but wide enough to get 2 panniers in side by side then one across the end and we are only 1 pannier and a tent short , if it tilts they can go on top as the c.g change should not be noticed....

Out with the Lego me thinks .......
 
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It's the links I am questioning ? surely they are to ensure when one wheel goes down the other if forced up ?

In this example does this force not get absorbed by the spring and not get transmitted to the other wheel ?
To be honest, I would not think the springs negate the tilting. If you imagine it this way maybe.....?
At rest with a rider seated and the trike upright BOTH springs are equally sharing the load of the riders weight and are in compression.
As it tilts the inside trailing link rises slightly and the free moving bearing of the cross-beam provides no resistance to compress the inside spring any further so the outside trailing link may fall lower.
IF a sudden impact (obstruction) forces either link arm upwards when the rider is vertical then the spring can compress because the cross-beam is equally loaded on either side of its axle.
That is how I see it, anyway. First one to build one can provide any proofs, of course.
 
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Dan

Thanks for the analysis , as you say the proof of the pudding is in the eating ....... better get a bowel and spoon ..

Seems the slot in the centre where the cross piece pivot is mounted because it has SUSPENSION !!!


More to ponder ...
 
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the bulk of the luggage is housed just behind the axles and despite all the doom sayers have not cause any traction issues.
Because the racing Snake has put on sufficient pounds to offset ANY AMOUNT of luggage? :ROFLMAO:
 
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Because the racing Snake has put on sufficient pounds to offset ANY AMOUNT of luggage? :ROFLMAO:
1:- Extra pounds can't be true ? I weight myself in Kilo's
2:- That is only ' winter ' luggage ! if the rain ever stops that should be gone in a month or two !
3:- beware 2025 ??? the Chinese year of the snake ' oh yes baby '
 
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I like the last incarnation from Mr. Solar tilting trike.
I can see how in his specific implementation it provides both tilting and suspension. Very neat.
But, his is still a skinny-mini trike; I doubt that track width is 24", how does it scale for a wider track?
Where he has his elastomer suspension unit, I would like to see a pneumatic shock-absorber that can be pumped up and hardened/softened though.
 
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So ideally the unit wants to be narrower than the 30" the existing rear wheels are , but wide enough to get 2 panniers in side by side then one across the end and we are only 1 pannier and a tent short , if it tilts they can go on top as the c.g change should not be noticed....
Yep - if it tilts the top of the wheels come inwards into the cargo area. If you stick with 20" and place a large cargo rack above the wheels high enough to clear the inside wheel on tilt and leave room for suspension you could narrow the track as it wouldn't be needed for stability. It'd also allow panniers to hang outside the top rack without becoming ridiculously wide. Effectively you'd be swapping the places of the wheels and cargo as you have it now - wheels inboard and luggage outside. It does mean your luggage amount is limited only by your ability to tie it on. If you add in a tilt lock such as a transverse brake disc it may make it easier to start and stop.
All these tilting mechanisms work best with a narrow track anyway. Go too wide and the amount of tilt gets reduced and/or the amount of travel of the two wheel arms needs to increase.

Narrow track


Wider track


As you can see you don't need to go much wider to substantially increase the need for the wheels to go much higher and lower. Going narrower ought to make the trike more street furniture friendly too. If you make the track no wider than yourself you've got piece of mind of fitting through gaps when not lugging anything and luggage will take any misjudgement when carrying gear which has to be better than a wheel or bodywork taking it.
 
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Instead of modifying your existing trike you could make an entire new rear end from the pivot back swapping the front and seat over only when ready.
 
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Instead of modifying your existing trike you could make an entire new rear end from the pivot back swapping the front and seat over only when ready.
Ahead of you there ;) I have just cut the fixed rear end off the Mk1 rear frame then I will weld another piece to make the rear spine as long as the Mk2.

That will give me a seat mount and pivot mount already made and as the Mk1 had no rear brakes it was not being used.

Once I have the welding done I will make the rear wheels and any frame they need bolt on to this spine.
It does mean that the rear ends will need rear brakes however that is the way I want to go anyway.

More on my Python thread when progress has been made ?

How is your suspension coming on ?
 
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Yep - if it tilts the top of the wheels come inwards into the cargo area.
However it will be hard though to mount the luggage on a part of the trike that does not tilt ? so should stay out of the way of the wheels.

Thanks for the drawings , more food for though.

The blue one will not be touched , I need to ride it 3-4 times a week and it does currently work as a camping luggage carrier.
 
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