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

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Dan

Don't be despondent I have an equally large pile of my own scrap in the midlands !



As you can see it closely resembles a Python bike , and that is because it is a Python bike !!!



It is to narrow to stand on it's own as as DannyC says when they decide to go [ over m] they go fast , well actually very fast ! there is no way of stopping them.



Did I say it was very narrow ? those rear wheels are withing the shadow of the seat !
I cannot ride it 1 dam foot ! , I gently trundled off the end of the drive for about 14' trying desperately to get both feet on pedals to no avail 😢😢



So I have one last experiment to do with iLean before it is back to FlevoTrike style centre ?
I build but never tried this , although it looks narrow I think the wheels will be about 24" apart so 4" less than current fixed trike.



So make a simple clamped piece of angle to join inside of BB axles together , find some way of clamping to existing frame and move over rear crank arms set @ 90' wheels etc
Can it stand , can I ride it ?

Paul
 
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In other news ....



So a look at the existing Flevotrike style middle frame , currently 2 elastomers to eliminate Yaw while I build a 2 axis pivot [ probably next job ]

However i feel as though I am on a knife edge and it has no self righting ability due to my weight easily over coming the elastomer's return to neutral force ?



So what would happen if I tried and reverse the 2 frame tubes ? so the seat is mounted on the front of the lower tube and that hangs under the upper tube which is fixed to the no tilting rear end ?

That would mean the elastomer and pivot were at the rear of the trike instead of the front of the trike ?

Is it important to have the pivot and elastomer underneath the seat I wonder ....

I may try up ending it clamping it to the workmate and seeing how it bends ?

Answers on a postcard please , usual address ...

Paul
 
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It IS i-Lean in principle, it isn't much more stable than the 2 trailing-arms and TBH, I hate it.
I think I will just chop it all up and do away with the forked front end and justr pythonise it for fun.






It looks to have a very high seat , was that part of the design brief ?

what height is it ?

I wonder if it will be stable/safe with say a 30" track rear end ? maybe you should try that before cutting it up to Pythonise it ?

Paul
 
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It looks to have a very high seat , was that part of the design brief ?

what height is it ?

I wonder if it will be stable/safe with say a 30" track rear end ? maybe you should try that before cutting it up to Pythonise it ?

Paul
:) It started out as a 30"+ track. I can't wheel it down the side of the house if it is that wide.
I shall think on all of the options before doing anything irreversibly drastic.
 
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Ok a little parable ?

Once in art class the teacher ask what I was doing , a bonfire in pastel's however it was not going to plan and corrections only made it worse ?

So he said maybe you aren't doing that but something completely different ? and with that he started rotating my picture and bingo 180' later there was an old man lit as though staring into a fire , quick hood and a mouth and we were in business !

So what has that to do with my Python trike adventures you rightly ask ? well I present to you my bonfire ...



This is the main frame of the Flevo/Python rotated through 180' [ do you like the symmetry in the stories ] ;););)



I described the current set up as feeling as though you were balancing on a rubbery knife edge , DannyC floated the idea of reversing the 2 parts so you sat suspended under the non-moving part rather than on top of it ?

So looking at this if I made a new lower part that picked up 2 elastomer mounts and the rod end swivel we may be in business.

The block of wood is 5.25" my usual keel height is 5" so if I copy my normal keel for the front leaving enough room for a front seat mount and the rear mount I am thinking of a 3/4" tube maybe 2mm wall straight through the lower frame and maybe 8" long with a matching tube on the seat back they can be joined by a couple of struts and we are in business ?



At the rear I just need a different upper keel/dead axle mount conveniently there are 2 sleeved M8 vertical holes [ old trailer mount ] nearby so we look good to go ?

Only fly in the umbrication is are the elastomers now mainly in compress or under tension ?

If under tension I think a strap is in order between the furthest left and the rear wheels to stop it tearing ? say limit movement in that direction to 1/2" ?

Another solution would be go for beefier elastomers ?

all the best Paul
 
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On reflection I don't think you'll gain much by swapping the two bars around. With just the bars the bike may stay upright at rest without a rider as the weight may pull it upright. I say may because the python pivot will play a large part in pulling it over too. With a seat on that weight is then over the pivot and vastly more so again with a rider so it will want to fall over without being balanced. It simply will not stay up without the centre of gravity being below the leaning pivot and achieving that seems impossible on such a design.
I still feel that bars on the fixed part that are also able to pivot fore and aft are the best solution and I suspect those elastomers will work much better in compression than tension plus any failure of them has much less severe consequences. . The bars would work similar to my tilter but would be better in that the bars wouldn't come towards you in a lean like mine and your's would need the pivot at the bottom.

 
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Popshot

It simply will not stay up without the centre of gravity being below the leaning pivot and achieving that seems impossible on such a design.
Hence below

I still feel that bars on the fixed part that are also able to pivot fore and aft are the best solution
I don't particular have control issues just the sat on a rubbery knife edge and my weight destabilising the balance rather than aiding it ? , see below

I suspect those elastomers will work much better in compression than tension plus any failure of them has much less severe consequences.
Agree see below...

Yes you are correct the Python front influences the tilt , however my plan is to swap the pivot over so the main load ME is sat underneath it and not on top therefore a degree of self righting will occur ?

Something like this :-



Tilt only no suspension.

Paul
 
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Just because the seat is ultimately mounted below the pivot does not alter that with a rider aboard the centre of gravity is well above the pivot and as such will want to tip. Every system will want to find it's lowest state and that is still with you on the floor. The pivot itself has barely moved and your centre of gravity stays the same so the flop will be similar.

TBH Paul I'm not sure of the use of the python system here. The python system necessitates a low seat which is something you're wanting to raise. I'm not saying this can't or won't work but questioning whether it'll result in what you want. It looks like a case of starting from where you are rather than starting from where you want to get to.
 
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Just because the seat is ultimately mounted below the pivot does not alter that with a rider aboard the centre of gravity is well above the pivot and as such will want to tip. Every system will want to find it's lowest state and that is still with you on the floor. The pivot itself has barely moved and your centre of gravity stays the same so the flop will be similar.

TBH Paul I'm not sure of the use of the python system here. The python system necessitates a low seat which is something you're wanting to raise. I'm not saying this can't or won't work but questioning whether it'll result in what you want. It looks like a case of starting from where you are rather than starting from where you want to get to.
This may (or may not) be correct Popshot, but I suspect Paul is going to be able to tell us pretty soon though. ;)
The Python front end with a smoothly operating pivot and the riders weight on the trike is always trying to get the thing (front-end) to sit-up straight. That behaviour will still exist and be trying to keep Paul on the upright path. But as Paul wants it to be able to lean into turns as well the flexible jointing between the two keels will permit this, and I can't see why it should not work reasonably well.

Really looking forward to seeing how this turns out. :p
 
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Hi all

I think what Popshot is trying to say can be explained by imagining a clock pendulum ?

Pivot above weight below [ normal ] will settle with the weigh as close to the ground as possible.
Pivot below weight above [ not normal ] will settle with the weight as close to the ground as possible , to do this it swings down past the pivot point.

So pointless trying to reverse the FlevoPython set up.

Time better spent:-
refining pivot to 2 axis
better seat mounts
reduce weight
allow suspension to work ?

Paul

ps and pursue wider damped iLean rear end...
 
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Just to hijack Paul's thread for a second or two.

I have the answer for my i-lean "standalone" stability....I think.

A strong bungee cord wrap or a spring between these two points will try to get the wheels and frame vertical at all times, but will allow tilting to take place.
No "lock", no fuss?

 
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Dan

Good man thinking out the box .....

What is the upper point you intend fastening to ? looks like it has a purpose ?

Implement away I say !!!

I have some open trampoline springs that may work a treat in there , shall I find them and post pictures/dimensions etc ?

Like these Ebay springs


Come in various lengths etc
Paul
 
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You'd need a butch spring to do that. May be better to build two arms off the central upright and mount two soft suspension units from them to the central swingy bit.
 
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You'd need a butch spring to do that. May be better to build two arms off the central upright and mount two soft suspension units from them to the central swingy bit.
I suppose that depends what his ambitions are ?

If DannyC only wants it to stand when he is not sat on it ? or stay up with him on it and no foot down ?

I suspect bungee won't cut it .....

Paul
 
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You are both correct in your observations, of course.
Rather than keep hijacking Paul's thread, I shall transfer my progress (or lack of) to my own thread.. ;)
Thanks for watching guys, it is much appreciated.
 
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Rather than keep hijacking Paul's thread, I shall transfer my progress (or lack of) to my own thread.. ;)
Not sure it is hijacking , it is on the same subject and another take on the problems involved is always welcome.

Paul
 
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Ok why no updates ? you may ask ?

Well have had injured my back , an ongoing problem and for my back it seems the final straw this time was wrestling with the Python iLean it was much to close to the floor and a heavy lump that just wants to lay flat (n):(😥

So been doing to much whilst taking it easy !

getting a bit better i wanted to ride my Oke-Ja to my mothers as i have not ridden it for nearly 3 weeks only to find I could not back it out of the bike shed ?

bearing in mind this bike was ridden 3 times a week up till my injury and regularly had the chain brushed with fresh engine oil I found this on the bike ?



Now the bike has chain tubes and the chain is only exposed at the front crank and through the rear mech I was gob smacked it was completely unusable !!!

So one afternoon was spent changing the rear derailleur for a NOS one adding a new pair of chains and a length of gear outer at the rear.

It now rides as it should , however Mondays forecast currently looks very bad so it may have been in vain .....

I have been beavering away at a 2 axis pivot to replace the rod end bearing , that is also pants and may not make the cut ?

Very clunky and not in good alignment.



Still I have successfully cropped the top main frame tube down to stop interference and have almost finished a new rear seat mount bracket to get that out of the way.

As the mule is a purely bolt together concoction it dawned on me [ you get a lot of time for ' dawning ' when your back hurts :) ] that the rear end of the trike could be upended so raising the seat ?



So the ultimate goal of this project is to safely ride a trike with a 20" seat and tilting , it gives us a 20" seat WOW , theoretically I just need a front end were the pivot centre is about 16.5" from the ground instead of the current 7.5".

it is not that simple if you look at the Flevo drawing ?



The seat on the Flevotrike is further over the pivot and I need to get the pivot angle as a python.
You can see the Flevo 45' angle marked and the fact there is some positive trail.

The unmarked dotted line is the Python 56' angle and that will almost give negative trail , I need to measure is and compare it with figures on the Python bike page.

Python_Projects_Survey

however it looks a good start and means I have 2/3 rds of a Flevotrike 👍:)

Currently I am working on the low version adding either double nuts or lock nuts to all the bolts so it can be ridden further than 200 yds from my garage.

Paul
 
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Well back still playing up so I bit the bullet many times and stripped the front end down and middle parts and painted them ....

Sadly in the pictures hammered copper Hamerite just looks like shiny rust DOH !



This is the new front end connected to the old rear frame/spine whilst I add all the bits and get it working again.



Chain on at least 6 speeds and a 34T front ring , front mech very near frame [ as rings need to be for chain to change at rear ] unlikely I will connect front mech as this is only a prototype/test mule.



Mudguard and pedals , no parking brake may be needed ?

From what I have read Flevo's are almost unridable without a steering damper ?

So I intend to fit this before trying to ride it.



Much to big , off a 1300cc M/C however it was cheap and will either work or show the folly of my path grasshopper



Paul
 
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