– The wheelchair must not have any camber on the wheels, or install additional jacks (without camber). Camber means at this idea a “slow down”!
– Ensure that there is distance between pedals and thighs. The hands must not touch the thighs!
– The distance between the pedals and the upper body should not be too large. The upper body should not move while riding (forward nor backward).
– Try to use steel (and not alloy). It is easier to find someone to weld it!
– Do not forget the ground clearance!
– Check the alignment (lining up) of front wheel and steering head (best on a “frame”).
– Make the frame strong enough!
– as seen at Noe‘s bike, improves “damping” of the pivot the driving characteristics (prevents fluttering).
, there are several possibilities: Springs as mounted at Noe’s Bike or similarly mounted gas shock absorbers.
Another cheap way should be with a screw slightly fastened to slow down the rotation. But I have not tried this.