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

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As you say hi or hello, then everything is fine.
They only have problems in Amsterdam with tourists and tgat is only because there are so many and walk on bike lanes and don't watch out.
 
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So another Python failure looms it's ugly head ?

Well not really ;)

When the Python was first built I was in need of a quick mount for the computer and so a piece of softwood was pressed into service.



On seeing it the wife said ' it's a piece of wood ! ' no sh*t Sherlock ,with all that welding you can't have a piece of wood .....

So I painted it black and it was not commented on again :LOL:



In the intervening years a front light was added and a strap for lifting/manoeuvring was re-sited there making it somewhat busy [ and essential ! ]

So while away camping on the August B/H the speedo got hit whilst mounting/demounting and the wood was badly split.

Time the temporary bodge was re-engineered so I give you the metal wood replacement.




The wood is on the right , the steel will use the same bolt hole and has a cross piece [ a bit of handlebar ] so the speedo can be mounted as though it was on a normal bike [ no more wood screws (y) ] the strap can pass through the handle bar with some plug ends and a joint hidden in the middle.

All that is left is a mount for the cheap light shown in picture 2 , it needs to simply clip on for battery changing however it must not rattle or fall off :ROFLMAO:;)

ps really nice to get the welder out and do 8 small welds without having to regrind the tungsten tip and get the current settings right ...
 
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Ok so finally painted and fixed on the utility post :-



Front light seems soundly held however we won't find out till we have ventured out into the bad bad world.



Speedo mounted as it should be with a sliver of rubber and it's proper clamp so no more wood screws/cable ties or wobbling Hurrah you shout in unison....

If I were to do this again I would actually weld the red bit to the seat post stub making it a bit shorter and with no bolt needed saving some weight , however hurry I was in .....

Found I can just about manoeuvre Python by grabbing a pedal and turning till it is vertical , so strap not yet added , see how we go.

So was Python ready for duty over this winter after tyres blow up to correct pressure .......

Well actually NO as the left brake did not work as lever would not move at all ! and the right brake barely moved/worked.

Removed left brake cable to find over 6" rusty cable at both ends and rest of cable very black , this is since August bank holiday ? a mere 7 weeks ago ? does not bode well for lasting the winter does it.

I was going to add some of those V brake rubbers at the back
plate end with a little grease in them , however that does not solve the problem at the lever end ? any thoughts apart from deploying some Magura hydraulics I have lying around ?

Talking of levers I have had to ground the left lever out [ the right needs doing ] :-



Without out that piece being relived it was impossible to change the brake cable without taking the lever off , very poor design IMHO...

Still need to do right brake cable , seems I constantly need rear cables and outers and now have a stock pile of fronts that are little use to me at present :(
 
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I agree that the rubber boot "ought" to keep the water & dirt out at the hub end, but the water entry at the lever end (where it is pointing upwards like a collecting cup on a recumbent deployment) isn't what the designers envisaged I guess. Are you using older style metal ferrules on that end or the newer and tighter fitting plastic ones Paul?
 
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We buy 10 rear brake inners and 10 gear inners at a time and a reel of outer cable , best value for money.
regards Emma
Twinkle

Evilbay I assume ?
 
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I agree that the rubber boot "ought" to keep the water & dirt out at the hub end, but the water entry at the lever end (where it is pointing upwards like a collecting cup on a recumbent deployment) isn't what the designers envisaged I guess. Are you using older style metal ferrules on that end or the newer and tighter fitting plastic ones Paul?
The outer's already have one metal ferrule so that has to go at the lever end as I find they tend to bind in the adjusters if used at the hub end ?
 
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The outer's already have one metal ferrule so that has to go at the lever end as I find they tend to bind in the adjusters if used at the hub end ?
If you have enough spare/slack outer cable length and they are either 4mm or 5mm diameter outers cut all the ferrules off with a zip-disc. I will send you hard plastic replacements for you to try?
I think I have 50 of each here in the mess.
 
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If you have enough spare/slack outer cable length and they are either 4mm or 5mm diameter outers cut all the ferrules off with a zip-disc.
I already have some of the plastic ones which is how I found out they are better at the adjuster end.
I won't worry to much about the existing metal ferrule as currently the inners are not lasting long enough to see any rust on them !
 
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I already have some of the plastic ones which is how I found out they are better at the adjuster end.
I won't worry to much about the existing metal ferrule as currently the inners are not lasting long enough to see any rust on them !
My thought in replacing the metal ferrule was that its isn't as fine an "inner-cable" hole on them as on the plastic ones and just maybe they would seal better.
 
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Ok so we are still riding it 2-3 times a week despite deteriorating weather.

Apparently the answer to my brake cable woes is :-
Stainless Steel cables
Low temperature grease

SO will buy some , however not before I have rotated the back plates 90' to get the adjusters horizontal instead of vertical



As a expedient measure I am dripping motor oil down inside the adjuster and that's seems to have wrought some improvement.

I found this yesterday :-



Tailbox only and full body..



The concept looks do-able on the Python ...

food for thought

in the mean time I will try and fit a Screamer fairing I have.
 
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Hi all

Well after all the great advice from members of this site the Python rear suspended axle was a failure , I don't think suspending both wheels from one pivot/spring really gains much except a weight gain [ the trike and not me ] and lots of work !

So after some more thinking I wondered if sliding kingpin ala Morgan 3/4 wheelers may be a better way to go ?

As the Python is a delta there are no steering problems with this suspension , I assume it can be both light and compact ?



So out with the trusty Lego I can see I will need some sort of anti rotation device hence the scissor link.
Hoping pillar could be a 12mm or similar bolt and the springs maybe die springs ? or similar ?
Lego also shows it will need some preload...

Any ideas ?

Sorry purely grinder/weld/swear engineering nothing lathe'd etc

regards Paul

ps and before the smart a**e on here points out that wheel is not 20" I had noticed ;)
 
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A swing arm would perhaps be less troublesome to make. Make the bushes for the bolts at both the chassis end and axle end 2" or longer and it won't want to twist plus a std bike suspension unit would suffice. As with all independent suspensions it'll lean outwards in a corner unless you use an anti-roll bar, though that'll only limit it not prevent it. Limiting the travel would be easier than adding an anti-roll bar. Do you have any pictures of the system that you've just tried but didn't like?
 
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Wot he said ^^^^^^^ Swing-arms definitely.
Independent suspension eh? You rascal, you will be making decent pivot's next. :ROFLMAO:
 
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In another flight of fancy, I looked at trying a version of the beam axle used on trucks, the type that have a leaf spring at each end with shock absorbers. The wheels can move up and down, somewhat independently for potholes, and together for spoon drains. The spring mountings keep the whole from moving sideways.

Let's look at the letter T in plan view. The top of the T is the beam, with a wheel, with a spring, each end. There are two pivots at the bottom of the T. One is situated to allow for "independent" wheel movement (potholes) and the other allows both wheels to move together (spoon drains). The spring strength or preloading should provide a compromise between softness and body lean during cornering. The pivots were made from bicycle headstems.

The idea worked, as far as I tested, but the build came to an end when I changed direction.
 
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Wot he said ^^^^^^^ Swing-arms definitely.
So pardon me for paraphrasing a soft southern jessie I know ?

' where's the fun in that ' ?

I think that is how it goes ?
 
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Stormbird: That one looks like it would only work when crossing drains or kerbs. Only one axis of rotation? If so, you would have little movement except when both wheels hit the same bump. If you were to place another rotation axis horizontal and perpendicular to the existing one, I don't see why it would not work.
 
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Perhaps a longer distance twix pivot and axle with a more traditional and longer suspension unit would help. It looks like the spring is almost coil bound at rest without any weight on it though it's hard to tell. From here it looks like there'd be very little suspension left after sitting on it. Also the pivot is just the width of the bracket. The narrower the pivot the more it's going to try to force that pivot into it's bushing rather than actually pivot with a force applied to only one end. It looks like a typical rear triangle bush which are basic at best and not intended to cope with twisting forces. I'd run two bars forward from the axle either side of your main rail (angle them just behind the pivot so they meet the axle wider apart) which should add some width to the pivot robbing the axle of some of it's leverage on that pivot and use 6 split flanged PTFE bushes (2 for each arm and two in the rail). Hopefully that should both help counter the twisting force of one wheel moving whilst allowing it to pivot more freely. Longer arms would reduce the arc the axle travels and as you'd be using the suspension unit pretty much in a 1:1 ratio of wheel movement to suspension unit movement (unless angled of course) it'd need to be a long one to allow enough travel. Even the bigger basic units only travel about 2" before bottoming out.

There's only one axis of rotation for a reason - to stop outwards lean in a corner. It's a compromise but possibly (probably?) the best compromise there is short of something quite complex, heavy and expensive. It is essentially a rear mounted version of what's discussed from post #14 onwards here. If you go independent then you have to either/and/or:

A. Limit lean by use of an anti-roll bar.
B. Limit lean by limiting suspension movement.
C. Accept lean as a trade off for comfort.

There seems to be a few high end taddies that are using composite leaf springs in a faux wishbone formation. Some of them don't have any lean limiting devices but do appear to have little movement so some are happy to accept lean as a trade-off though I suspect one of the main reasons they use the composite leaf springs is to save weight over a steel axle rather than for their suspension effect.
 
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