Tilt trike suspension front end for a tadpole?
- Thread starter Dana Joy
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As the title of that thread suggests I've built 3. The first was awful. The second worked but with limitations. The third is perfectly usable, gets a lot of admiring looks and is the best system I'm aware of. Unlike many it separates tilting from leaning so you can apply differing amounts of either to suit the corner. Downsides are complexity and therefore cost and weight.
I know you specifically asked for tilting with suspension and the mk3 has no front suspension. The mk2 had and that was the bulk of the problem. There were a lot of geometry compromises to cope with tilting and suspension movement and just getting on and off was a major undertaking because of the positioning of various pieces. It can be done but expect those compromises to ultimately detract from any real use. The mk2 thread is here.
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There is as they say more than one way to skin a cat ?
Post #884 onwards this is my Delta Python trike and it tilts , nothing complicated ' does what it says on the tin ' [ Tilt#3 ]
I am still riding it now [ Tilt#6 just narrower and higher seat ] 3 times a week and it has been to the Netherlands towing a trailer , so no hanger queen.
Paul
Post #884 onwards this is my Delta Python trike and it tilts , nothing complicated ' does what it says on the tin ' [ Tilt#3 ]
I am still riding it now [ Tilt#6 just narrower and higher seat ] 3 times a week and it has been to the Netherlands towing a trailer , so no hanger queen.
Paul
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I'm not sure what a regular front suspension unit is on a non-tilting tadpole trike let alone a tilting one. Suspending tadpole front wheels is difficult at best and going to make matters worse at worst. You can utilise sliding kingpins like this...
Or if you feel adventurous like this..
This has the advantage of simplicity but the drawback of slop in the fixing of the wheel with the simpler of the systems as very few joint systems are designed to slide in that manner. You need a strong sliding component to take the stress. The worry is the wheel juddering under stress. If you go this way then have the axle above the chassis as the top picture. Placing it under means the exposed non supported kingpin to axle mount length length is at a maximum meaning extra stress. Above, as per the picture, keeps the extended part of the kingpin in the lower stress role of suspension tie-in only. Suspension sag will eliminate some of that advantage but not all by any means.
There is what may be termed standard wishbone suspension.
Advantages are good control of the wheels and can be designed to have no bump steer. Disadvantages are extra fabrication and needs planning to clear heels and chain runs etc.
Then there's Macpherson strut.
Advantage is good control. Downsides are weight and strain on chassis design. Note the size of the chassis to the top of the strut.
One of the best front suspension systems IMO is composite leaf.
Simple and elegant. Difficult to get the correct rate without trial and error.
One of the big downsides to any suspension is the steering arms. The arms have to move to accommodate the wheel movement. This ideally needs a pivot in the steering arm in direct alignment with the pivot of the suspension so as to not lengthen or shorten the arm length required as the wheel moves. This generally means lots of linkages so complex and expensive. Failure to do this leads to bump steer. This starts to get awkward to plan and build on a non-tilter. Add tilting into the equation and your list of design necessities gets longer. You find a solution to the problem only to find you then have no acceptable route for the chain or similarly two components wanting the same space under differing conditions (a steering draglink is particularly an issue of wanting space it can't have). It also means the rod ends need a LOT of extra articulation to accommodate all this extra movement. Running out of a rod end's movement arc is going to end in disaster. I had to utilise special spacers to maximise rod end articulation. It can be done but you need to plan carefully and/or have an ability to envisage the whole system in your head as it moves.
Another drawback of any type of front suspension on a non-tilter is it encourages the trike to lean out in a turn so keeping the suspension movement small is desirable. Tilters do not suffer this issue. Pretty much any suspension system can be utilised with a tilter but expect issues to arise with regard to everything moving as it needs to. Use rod ends with thin casings and alignment spacers to maximise articulation and unless you can overcome every design issue to get perfect geometry at all lean angles and steering inputs expect performance to suffer due to those compromises. It was the compromises that cost my mk2 tilter it's place and it has since been recycled as a result. The non-suspended mk3 is a vastly better machine.
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