On Jun 4, 10:01*pm, someone wrote:
On 3 June, 00:35, Andre Jute wrote:

THE LOGIC OF TRIKES
an outsider's viewpoint

Considering a lightweight trike like a motor vehicle is incorrect.
The major problem for which you have identified is that the angle from
the centre of gravity to the line between the outer front wheel
contact and the rear wheel is too steep. *Other than making the track
wider or lowering the rider to which you dislike on both counts, there
is the possibility of laterally moving the rider. *

Yes, I mentioned this possibility to Bernhard. Search for
"sandracing".

A wide flat seat
may be provided with grab rails to the side. *The rider would need to
relocate and brace for the corner using the outside grab rail. *The
simplicity of the system relies on the alertness of the rider for all
cornering over modest speed. *The steering bar itself could be used as
the bracing just as it is when a racer laterally shifts the bicycle to
enable pedalling through a corner.

The bench set is clever, though it will have to be somehow supported
and then we're moving from the simple, lighweight chassis I first
posited. Without the sort of drive contortions I mentioned in my post
to Bernhard (a seat boom pivoted near or on the bottom bracket, a
universally jointed driveshaft) the amount of possible movement will
be small if drive is to be maintained. Frankly, I think just making
the trike wider than the 44in/1120mm or so currently considered a wide
track will do the job better than acrobatic contortions.

An alternative to the above is a relocating front axle, not nearly so
good, but saving constant attention. *

Now this is a much cleverer idea, It might be possible to build the
suspension onto a kind of pantograph, which will also contain the
progressive spring which will further control the tilt. But all this
is complication and it is going to weigh.

The idea is that upon turning,
the 'axle' is moved outwards so setting up a 'lean' in addition to
what the rider does with his upper body.

The most satisfactory system will probably consist of the relocating
axle, relocating seat plus body lean which is partially induced with
an automatic seat relocation. *I'm thinking that seat relocation may
be up to 200mm, axle at 140mm plus a further body lean at the shoulder
of 200mm. *If all this was done with a Jute height seat with a 6oomm
track, would this enable sufficient cornering angle on a typical
adverse camber?

600mm track is invalid carriage territory. I was thinking of 56
inches, to be certain to keep the entire thing under five feet; these
are arbitrary numbers. Bottom of seat would be in the order of 360 to
420mm high. If the rider wants to sit with his back at a comfortable
angle, the CoG of this trike will be 400mm or possibly up to 600mm
above that of a typical fully reclining trike. You're not going to
make that up with fiddling the axle a little this way or that and/or
whole-body shifts limited by the need to keep pedalling. (Body lean
I'm discounting as already accounted for -- this after all a
comparison with existing designs, not a blank sheet.)

If the answer is possitive then the design may be considered. *Else
I'm thinking the track just has to be wider. *

I think we're there. 600mm track was never a starter for a fast
comfort-trike except of very limited cornering ambition. I define
"fast" as touring speeds (downhill on a mountain, how fast do you want
to go around which corners?), not racing or record-breaking.

If it could be done
along my principles then how far could the machine be narrowed?
Making the machine less than 500mm is some accomplishment when coupled
with a high cornering speed.

I shan't be volunteering to be your test pilot. I think a narrow track
as a parameter of "goodness" of a trike design is as counterproductive
as the one which made the current crop too low for anyone except a
contortionist to use.

Frankly, whether your sideway weight relocation ideas are any good
depends on how much heavy complications they add. But I like them as
out-of-the-box-thinking. We have too little of that on RBT, a supposed
technical conference, and too many morons running around trying to put
a damper on our natural exuberance.

Andre Jute
A little, a very little thought will suffice -- John Maynard Keynes