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

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Today I had some fun with flames !



This is a standard MTB rear frame for 20" wheel , hopefully it will be repurposed as a Flevo/Python trike hybrid [ really need to find a name for it as that is very clumsy :whistle:;) ]

The plan is to heat it where crosses the 2 stunt pegs and bend each leg down as close as possible to the red bar ...



Simples you say ? well 5 minutes latter with one plumbers torch we had not even caused the paint to bubble.

So we used 2 torches and a few minutes latter it worked , the first one spread a little at the bend the other was faster and better and neither split which was my big worry.



Now where is it going ?


So it will look like this



probably need to tweak it's location a bit ?



The suspension pivot may be slightly below the main tube to allow room for the shocker absorber , apparently they are better for bumps as the elastomer normally used has a habit of bouncing the front wheel off the road going over speed bumps [ this is probably bad ! ]

I have springs of 350lb - 550lb and 650lb no idea which will be best does anyone have a 450lb to donate to the cause ?

all for now Paul
 
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That Hammerite looks like '70's brown. Are you still planning on using rim brakes on that front wheel? Will the arms and block mounts cope with that bend?
 
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That Hammerite looks like '70's brown.
Of course it is ' proper ' Hammerite so has the nice ' pooling ' look , not the frankly ineffectual modern stuff.
However it stank the house out for 4 days hardening off before the smell abated , what's a few VOC's amongst family ?

Got it along with 2 carrier bags of other ' unused ' but ' unpopular coloured paint ' both Hammerite and Enamels when dumpster diving whilst on holiday in Frome many years ago :whistle::D(y) looked like someone clearing out an old hardware shop.

Are you still planning on using rim brakes on that front wheel? Will the arms and block mounts cope with that bend?
It's a delta trike so will have brakes on the rear wheel's , I left the brake studs on it case some short reach arms may fit in as I may want a separate parking brake ? If nothing will work they are coming off.

Obviously to busy up there for a side pull rim brake , however depending on the front wheel used I may be able to deploy a hub brake ?

Paul
 
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So did this today ?



A stab at measuring the negative trail my current Python has ?

<> 20 cm - 8" however is that a lot ?

Well there is a Python spread sheet of projects on the Openbike Wiki looking at the projects I find

highest trail recorded 32 cm
Average trail recorded 22 cm
Lowest trail recorded 14 cm

So sat bang in the middle , although a lot of the projects are bikes rather than trikes.

I now need to get that figure into the new trike somehow ?

Paul
 
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Whoa we are moving into uncharted territory here ~?



The Flevo trike/bike has strange handling [ rather than a Python ] because of it's steering angle [ green line ] and resulting posotive trail ?

So to Pythonise it I wanted to build in my Pythons 56' [ red line ] and 20 cm of negative trail [ blue line ].

That moves the steering pivot back quite a bit .....

What is the result of that ? not sure ?

Paul
 
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Here is my Python parked purple-dickular against my workshop wall.
A threaded rod inserted near the pivot gives an indication of the trail on the trike.

The rod is about 3/4" ahead of the centreline of the pivot so the trail is probably 19-20cm?
Do y'all like the way I have mixed imperial measurements with metric ones there ;)

 
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Dan

Thanks useful stuff.

Paul

ps all bolt sizes to be in Whitworth from now on ?
 
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So one of today's task is looking at deploying the steering damper ?



Probably much to big , however cheap off Ebay and just a test so will do.

In the picture you can see the pivot @ 56' this means the point where the end ball joint sits on the left goes both up when traveling to the right and down when traveling to the left.
So the mount shown on the casting may need to be moved through 90' depending whether up/down or left/right prove to be the bigger movement arc ?



A simple bracket may suffice mounted on one of the M8' used for the left handle bar ?

The other bolt through the casting rod end can probably be fastened to the M12 going vertically with a simple bracket ?

I realised this motor cycle damper whilst providing the function of damping the steering does NOT actually provide the same functions as the rubber elastomer diablo on the original Flevo Trike as that is able to hold the steering in the centre ? is that important ? we may find out soon.

Paul
 
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Other days task ?



looking at the new builds front end ?

So I need to try and get a suspension shocker in the front end , at right angles to the front fork [ the whole rear end of a MTB bike ] , and @ 45' to the main frame shown arcing across the front wheel.

As can be seen the pink bracket is way to deep and the yellow pivot spacer tube can also loose a bit maybe ?



The two loose upper frame parts [ seat stays ] need trimming and squeezing down to meet the chain stays that will create room for the shocker.

I think the lower mounting can be a tube through or half recessed in the chain stays , however this shock absorber has very little travel ? [ as can be seen in the picture ] maybe less than 2cm does this matter ?

Paul
 
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Hi all

So it is back together with paint and lot's of either double nuts or lock nuts , cable ties etc.
A steering damper is fitted and has slowed the steering down and limited the lock , there is more lock right than left , however it is a left turn in the cul-de-sac and it makes that easily , I think the controlled tilt reduces the turn radius which helps.

and ready for trials ?

Well it maybe , however it ain't going well !

Mode 1 handle bars on front steering part
It is almost impossible to start off without using the slope on the drive ?
The brakes are holding the un-tilted rear end however the bars are unable to hold the tilt and any move to raise a foot off the floor towards a pedal causes a tilt on the side where the foot was lifted from then front end joins in as well [ although without steering input , in other words it does stay pointing ahead ] and also tilts.
It takes 4 of 5 attempts before I am riding and it is not pretty , sometimes I only get a few yards before I have to stop.
Very typical Flevo/Python 2 wheeled behavior , NOT what I want !

This is all very odd as I have a 2 wheel recumbent and a big headed trick [ me ? ] when others have tried to ride it and done a wobbly circuit on it is to trackstand it then lift a hand to wave and ride straight off [ I get it right 9 times out of 10 ;) ]

So why can't I get the trike to do that ? is it because the distance between the C of G of the tilting part and the non tilting part is very small ?

I really want to use it in this mode for safety [ and maybe can with practice ] however I did not expect it to be almost impossible.

Mode 2 handle bars on non-tilting part
So instantly ride-able not elegant and maybe not right but forward progress can be made and of course years of Python riding make the pedaling/steering only mildly strange.
Again it goes down the road with me not sat vertically , yes there is camber and I am tilted towards the crown of the road.
However if I ride down the same side in the other direction I am now tilted towards the gutter ?
No idea what is going off there.
I try to use the bars to get vertical [ or perceived vertical ] and it seems to fall past vertical and end up tilted on the opposite side , almost like vertical is so narrow a knife edge I cannot balance on it ?

I have some problems to fix , the brakes are poor - cables to long I think.
Chain skips at front , there seems no adjustment left on the lower stop may have to try a longer bolt in an attempt to lock the lower ring out.

I can see that any tilter relying on a tilt-lock being released and riding off is fraught with problems , I doubt if most peoples reactions are fast enough to catch it before it goes pear shaped ?

I need more seat time and some more thinking Paul
 
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Hi all

On a less gloomy note I found this thread Finnish Flevo trike been in contact and have been given some guidance steering re-pivot angle trail etc..

Their conclusion was any pivot angle could work with 0' trail ?

They have used the standard Flevo 45' and just lengthened the front between pivot and pedals till 0' where hit and the handling is much better.

They also suggest getting 0' trail on the tilting pivot ? not sure why that is desirable ?

I have ordered the correct steel for a normal Flevo front fork and the correct dampers to build a standard bike/trike front end.

all for now Paul
 
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You can have your cake AND eat it. Put the bars on the non-tilting part, pivot them at the bottom and run rods to the steering part. Balance and steering, dual purpose bars. It doesn't have to be either / or.
 
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You can have your cake AND eat it. Put the bars on the non-tilting part, pivot them at the bottom and run rods to the steering part. Balance and steering, dual purpose bars. It doesn't have to be either / or.
I get the idea and sentiment, but bars that move (as they must to push "linkages") means you cannot balance easily or use the bars to prevent a tilting action from occurring.
 
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You can have your cake AND eat it. Put the bars on the non-tilting part, pivot them at the bottom and run rods to the steering part. Balance and steering, dual purpose bars. It doesn't have to be either / or.
I get the idea and sentiment
I'm with him !

I don't think the brain could cope with dual function levers , especially in a panic situation ?

Also when I visualise this I see the bars being mounted on a solid rear end trying to connect to the moving front end.

The front goes up and down when it steers ?
The front goes backwards and forwards when it steers ?
The front will also tilt in relation to the bar mount ?

I can see these all eating into the available travel and so restricting the front end movement.

I would love to be proved wrong.....

Paul
 
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I have them on my tilter and it's a perfectly easy and intuitive set-up to use. Don't forget that because you are leaning the amount of turn is very little.
 
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Ok , strangely it's not me !!!



Couple pictures gleaned from a Flevo bike club blog , look at the front wheel of the Flevo in the back ground !



And a bike and a trike both apparently traveling forward with the rider roughly upright and the front of the Flevo NOT upright !

Pictures found here :- Flevo/Python blog

So I think I had better stop worrying about the front's angle and just get on with riding it !

I have added very short brake cables so have better braking and moved the bar end extensions more horizontal , seems more comfortable.
To remove the front bars I have had to make a new steering damper pivot mounting and it foul's the damper a little at full right and so needs trimming.
Still another 2 short trips out the cul-de-sac , and 1 slightly longer one.

Despite only maybe traveling a mile so far , it is probably a mile further than any other Zombie on a tilting Flevo/Python hybrid (y)

Paul
 
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Well done Paul!
Nice of you to "take one for the team" in this fashion. :D
This is on the adapted "Mule" I assume?
 
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