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Design of front suspension for leaning recumbent trike

October 18, 2023 — BarryK

I posted yesterday about preliminary design of front suspension for a tadpole recumbent trike:

I wasn't going to, but then thought, hey, why not go the whole way, and make it a leaning trike?

In yesterday's post, I did say that the rider can lean into a corner. This is, however, fighting against both the strong shock-absorbers and the momentum that is throwing the rider outward. The result is that the rider might not be able to achieve much of an inward lean of the trike while going round a corner.

However, there are trike designs that allow unrestricted leaning. There are two main mechanisms to achieve this:

  1. The trike is balanced like a bicycle. The downside is that when stationary, the trike will fall to one side, necessitating some kind of lock mechanism (or feet on the ground).
  2. Leaning is linked to the steering mechanism. This tends to be the most complicated, and there is likelihood of hitting bumps getting transferred back to the steering.
As to why a leaning trike is a good thing:
  1. The trike can be narrower, as the leaning will greatly lessen the tendency to roll outward while cornering. This will mean I can achieve the 660mm legal width here in Western Australia.
  2. The wheels will lean just like when cornering on a bicycle, causing greatly reduced stress that is  tending to buckle the outer wheel on a normal trike.

Here is a drawing that shows why leaning into a corner is both good for the wheels and to avoid tipping over:


There have been a lot of leaning trike designs, in many cases some guy tinkering for years in their garage. Some even made it to being manufactured; however, to my knowledge they were all short-lived and there is no manufactured leaning (human-powered) trike currently in production.

Which does lead to the question; is there something wrong with these designs? Too complicated? Too expensive? Not adequately marketed? Handling quirks?

Here are some of the leaning-trike projects that I discovered yesterday:

Rick's trike. Balance like a bicycle, with a lock when stationary. No coil suspension

Panthertrike. This is a delta trike, leaning but no coil suspension

AR3. Leaning, but no coil suspension

EATSRHPV. Leaning via steering linkage, with coil suspension
Martin lives in WA!
Impressive, but complicated!...

Panthertrike and AR3 were attempts to manufacture. Martin's EATSRHPV and Rick's trike are personal projects in a garage.

Here are some photos and links to lots of leaning trike designs:

This drawing shows that if the place where the two shock-absorber coils meet, is able to move independently of the trike body, then leaning is achieved:

img2, when stationary, that meeting-point can be locked in place to prevent the trike from falling over. Acknowledgement: the above two drawings are taken from here.

It is possible to take the above design one-step further, and use just one shock absorber.


...but then the ability to lock the trike upright when stationary is lost (maybe), and the rider would have to put the feet down on the ground, just like a bicycle. Acknowledgement: photo taken from here.

Applying this single-shock-absorber principle to my design, except have it on the bottom wishbones:


...the main shock absorber has been placed between the two lower wishbones, see "shock absorber" above, and if attached to the existing mount-points, suits a 325mm shock absorber. I do not yet know the optimum length and coil-strength of the shock absorber; will probably just try and see.

As far as stability when stationary; well, might not need any kind of bracing or locking. The reason is, the above design, where the wheels are fixed a certain distance apart, which is the situation when stationary, any roll off vertical requires compression of the shock absorber. This will be another try and see.   

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