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

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I think that what we are most used to is pulling the steering "levers" fore and aft in opposite directions and that is what our mind/muscle connections are well versed in.
This arrangement really wants us to split the directional input into 2 completely discrete elements.
Left/right with respect to forward motion with our legs, and tilt left/right at the same time with our arms (when our mind is screaming "pull harder to make the turn"). It may all be counter intuitive at first.
I suspect (but don't know) that if you took someone who had no "previous" conceptions as to how such a trike could/should steer then they might get it under their belt quicker because they are not fighting "known behaviours" and will just make it happen.

It seems to me that any arrangement with 2 Axis at 90° to each other will always have the ability to introduce 6-degrees of freedom as it will combine some elements of both pitch & yaw to varying degrees.
How we control this and limit the "floppiness" (if you will allow the word) is the trick. You could ingest large doses of madixxadroopin or Macoxxafloppin if the whole thing isn't stiff enough. ;)
Many wives recommend these drugs for their men.
 
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I think that what we are most used to is pulling the steering "levers" fore and aft in opposite directions and that is what our mind/muscle connections are well versed in.
This arrangement really wants us to split the directional input into 2 completely discrete elements.
Left/right with respect to forward motion with our legs, and tilt left/right at the same time with our arms (when our mind is screaming "pull harder to make the turn"). It may all be counter intuitive at first.
I suspect (but don't know) that if you took someone who had no "previous" conceptions as to how such a trike could/should steer then they might get it under their belt quicker because they are not fighting "known behaviours" and will just make it happen.
I am quite used to riding the Python no handed I can put on/off a sweatshrt make a phone call eat and use a camera whist riding [ although not all at the same time ! ]
What I think the problem is currently there are NO effective controls to ' control ' the tilt , it only changes by accident and no by design.

It seems to me that any arrangement with 2 Axis at 90° to each other will always have the ability to introduce 6-degrees of freedom as it will combine some elements of both pitch & yaw to varying degrees.
I don't think that is correct ? [ prove me wrong ]
I have :-
Yaw - swinging from left to right - rudder etc
Pitch - nose up down - elevator
bank - wings low left or right - ailerons

This one does not have YAW ?



not even sure what this one has ?



Best picture I have of a small amount of YAW on mine ?



I have seen much more just not taken a picture ;)

How we control this and limit the "floppiness" (if you will allow the word) is the trick.
Yes

After changing the handle bar configuration I will consider adding the second elastomer in line with the first and about 6"-8" behind it.

That will stiffen up the selfcentring allowing it to stand unaided easier and hopefully add a little more reluctance to it tilting ?

Paul we live in interesting times ....
 
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You could try dual purposing the bars. If you mount them on the fixed side but pivoted so they move in a fore and aft motion you could then send links forward to the front end with rod ends each end. This means pull up / push down to lean and pull /push fore and aft to steer. It's essentially similar to my tilter. Simples.

 
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I don't think that is correct ? [ prove me wrong ]
I have :-
Yaw - swinging from left to right - rudder etc
Pitch - nose up down - elevator
bank - wings low left or right - ailerons
No you are correct and I was wrong on this point. The trike example shown can only rotate around the stub-axle through the bearing assemblies. No left-Right/Up-Down.
So it can only lean left/Right. Your rod end version does allow 6-DOM as it is a ball in a socket.
 
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You could try dual purposing the bars. If you mount them on the fixed side but pivoted so they move in a fore and aft motion you could then send links forward to the front end with rod ends each end. This means pull up / push down to lean and pull /push fore and aft to steer. It's essentially similar to my tilter. Simples.

Popshot thanks for this , one for the back burner in the draw ' If all else fails ' !

Your rods running forward to the front will have a hard time as the pivot is not vertical ? does that mean the bars pivot would have to be the same angle ? i can see this would cause a limit to the achievable steering angles achievable it is possible that would not be a bad thing !



Paul
 
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The trike example shown can only rotate around the stub-axle through the bearing assemblies. No left-Right/Up-Down.
Ok getting myself confused over terminology so going back to basics :-



if I try to translate this into trike affecting actions ?

Roll is the Tilt
Pitch is the suspension IF this is allowed by having a rod end bearing AND if there is a single elastomer [ yellow trike in #602 has no suspension ]
Yaw is steering and if combined with Tilt becomes Lean steer - now I think this is the bogey man here and needs dealing with.

My view is that as I ride the trike , I approach a bend and initiate steering with the Python front end , now either consciously or because the Python front end tends towards a slight left/right nod when pedaling the upper part starts to both tilt AND yaw giving me lean steer.
To me the amount applied is completely uncontrolled as like all lean steering systems being a component of the lean and that is dependent on the speed and not the turn radius ?

Current plan is to try a better handle bar position and prepare for a strip down to reinforce the front pivot plate and add a second elastomer.

Paul
 
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You are right in that you'd need a lot of articulation in the rod ends. The use of slim outer housings and misalignment spacers would give the biggest range of movement. You'd need to mount to give the best possible motion range in the tilt plane as you'd need comparatively little range for actual steering. I expect you'd get enough articulation. Keeping the arms parallel when upright and as long as is practical will help.
 
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Ok getting myself confused over terminology so going back to basics :-



if I try to translate this into trike affecting actions ?

Roll is the Tilt
Pitch is the suspension IF this is allowed by having a rod end bearing AND if there is a single elastomer [ yellow trike in #602 has no suspension ]
Yaw is steering and if combined with Tilt becomes Lean steer - now I think this is the bogey man here and needs dealing with.

My view is that as I ride the trike , I approach a bend and initiate steering with the Python front end , now either consciously or because the Python front end tends towards a slight left/right nod when pedaling the upper part starts to both tilt AND yaw giving me lean steer.
To me the amount applied is completely uncontrolled as like all lean steering systems being a component of the lean and that is dependent on the speed and not the turn radius ?

Current plan is to try a better handle bar position and prepare for a strip down to reinforce the front pivot plate and add a second elastomer.

Paul
With reference to the RED trike on page 602.
As shown, the elastomer can get vertically squashed/stretched because the pivot providing the transverse axis allows it as the rider gets on the trike or it goes over bumps in straight line this is a small-scale "pitch" axis providing a modicum of suspension effect..
The red frame can only twist around the stub-axle of the bearing equipped affair on the longitudinal axis of the trike, it cannot move in a left/right direction as seen from the riders seated position. That stub is solid the bearings & shell will not allow any other movement other than twisting round that stub. This distorts the elastomer from its "column shape", this is the tilt axis.
A combination of the "Tilting" plus the turning l/R of the Python pivot (not shown in the picture) steered by the riders legs and/or bars attached to that forward section will produce an overall effect (adding every action together) of a "roll" into the turn for the rider on the seat. No?

I like the solution on the RED trike. It is very neat.
 
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I can't see enough of that red trike to explain what happens. There's a bolt running accross the frame which suggests the elastomer is suspension only, ie no tilt function. There's a longitudinal bolt under that which hints at a tilt function but the bracket for the first bolt disallows this. It's possible that second bolt is merely mounting the bracketry for the first.
 
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Ok so further rides have been under taken.



I have kept the bars mounted on the non-steering part and changed the orientation of the extensions and swapped the brake levers around to end up with this arrangement.



The extensions are obviously to wide , however we are only playing with possibilities here.



Even stood as pictured we have some YAW.

So what happened ? 2 more very short rides were made.
It is definitely more ridable , some observations were made , in no particular order.

It seems better to start the turn before starting to tilt , no sure why just a gut feeling maybe a turn is harder to start when tilted ?

At times I was riding along thinking everything was fine , however when I looked up [ I seem to spend a lot of time looking at the trike for problems etc ] I noticed I was riding along with some tilt.
However it seemed hard to detect with no reference point in my vision ?

It seems easier to level the tilt element by pushing the low side up than trying to pull the high side down maybe it is a muscle/orientation or efficiency thing ?

the suspension seems to work to some degree ?



The red tubes grip the upper main frame and are approx 56mm from the lower frame.

I went up the 1" curb to my drive which then slopes upwards lifting the front end and the upper tube upwards in relation to the lower tube , there was a clunk from the back which I assume was the upper tube hitting the lower tube ?

So what to do next :-

bars are currently to loose and swivel easily - better job of locating them needed.
strip down frame parts add fittings for second elastomer
add strengthening plates to front pivot mounting
adjust to get more gears

So plenty of playing to be done.

Now this will really annoy DannyC ? the trike as pictured above was sat on the front path after the rides , there are no brakes on and NOTHING propping any part of it up !
I went upstairs for my camera and when I came back it was still stood like that !
It gets better I then got my normal Python out and stood it next to it for some pictures.



It still stood there ...



And still standing when I put the other Python away !

I did go and nudge the front end where it then fell over till the pedals touched the path , it goes with quite some speed [ much like a MBB ] and would cause some injury if you got in the way.
I am looking at a stand like the FelvoTrikes have on the left side to introduce a lean away from the weight of the pedals mainly to stop the chain rings getting damaged.
I am also investigating a FlevoTrike steering damper



The centre elastomer called a Diablo rumor has it they are used to fasten the mast of a sailboard ?
I think steering damping would be good to help even out my pedaling with no handle bars on the front.
Will also control the front end when stationary , and eliminate the sudden flop of the front end ?


Paul
 
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Now this will really annoy DannyC ? the trike as pictured above was sat on the front path after the rides , there are no brakes on and NOTHING propping any part of it up !
I went upstairs for my camera and when I came back it was still stood like that !
It gets better I then got my normal Python out and stood it next to it for some pictures.
Well, it should stand up un-aided without brakes etc. etc. because it does not have tilting rear wheels and is only a half-tilter. ;)
Really pleased for you, because it is all moving in the right direction with some challenges to overcome, but generally fulfilling the design brief you set out with.
 
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Well, it should stand up un-aided without brakes etc. etc. because it does not have tilting rear wheels and is only a half-tilter. ;)
Half true !

The upper part that tilts includes the whole of the front end and is considerably heavier than the lower non-tilting part , and figuratively speaking it is balanced on a knife edge of 1 elastomer and the contact point of the front tyre , even a gust of wind could be enough to cause it to flop over ?

Paul
 
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I can't see enough of that red trike to explain what happens. There's a bolt running accross the frame which suggests the elastomer is suspension only, ie no tilt function. There's a longitudinal bolt under that which hints at a tilt function but the bracket for the first bolt disallows this. It's possible that second bolt is merely mounting the bracketry for the first.
Popshot I see what you are saying and well spotted some of the stuff is just there because a Flevo Bike [ the red bit ] was turned into a trike by adding the silver bit ,you can see the redundant rear fork pivot just above the elastomer.

However it is really just inspiration to eventually replace the vertical rod end with a 2 axis bearing assembly giving tilt and suspension.


Paul
 
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However it is really just inspiration to eventually replace the vertical rod end with a 2 axis bearing assembly giving tilt and suspension.
This sounds like a very good idea and may work far better than the current Kami-Kaze "Banzai! I die for the Emperor" diving into the ground version ;)
If you still find yourself "listing" to one side while travelling in a straight line, fill your pockets on the opposite side with an increasing number of fishing weights until the correct "trim" is established. :D

This Python-Tilt project is very interesting and you may end up with your ideal trike if you aren't careful.
Put a Bafang on the front when you are too old & tired and it can become your personal Tuk-Tuk.
 
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Ok proof of suspension ?



Above before it was ridden ?



After being ridden there is a rust mark each side and signs of abrasion ? that is where the front has risen and the suspension has pushed the rear of the top frame member down onto the rear of the lower frame member causing the seat mount to touch the frame !

Currently in bits for second elastomer mount being added - just needs 2 anti crush tubes and a 6mm spacer welding in.

Then look at handle bars to improve clamp
and
braces for from pivot mount.

steering elastomer ordered should be here in next 2 days.

Paul
 
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So more done ?



Now we have 2 elastomers maybe a step in the right direction.



You can see even stationary there is some tilt available even without me sat on it.



However Yaw almost gone.



Turn of course is mainly a product of the front pivot and not tilt/Yaw now as the whole lot is stiffer.

Does it ride any better ? hard to say as I still need to make a better job of fixing the handle bars and attending to both gear changer's
2 more short rides done , a couple of times in them I have been distracted again and though all was well , however when I looked down the trike appeared not to be level.
Correcting that appears to cause problems as then you have the feeling ' level ' is a knife edge that the trike does not want to sit on , and it is much happier chugging along with a slight lean to the right or the left ?

Maybe ' level ' will just come if I don't spend my time trying to get it level ? perhaps I am fighting the trike and should leave it to it's own devices ?

puzzled Paul
 
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As you say, steps in the right direction. :)
Does it always lean to one particular side?
Is the side it leans to on the camber of the track/road?

Remember, it leans because it can, and that he hard-framed Python with no elastomers cannot. ;)
 
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Does it always lean to one particular side?
Not ridden it enough to find that out , yet !

Is the side it leans to on the camber of the track/road?
Good point not though of that , it certainly does not feel like it is trying to uncontrollably tilt any further than it needs to [ if you see what I mean ]

Paul
 
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As the tilting part is on top of the fixed part you are always balanced on a knife-edge, I wonder what would be the effect of under-slinging the front section?
As discussed, If there were 2 x Rod-ends and elastomers (tilt resistors) sandwiched between the fixed/tilting beams; would that work better?
 
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