*for big bikes
In thinking about jumps and rollers I assume the safe bet is to make them smooth (not too jerky/bumpy) for bigger bikes as they have the biggest wheel base. For extra large 29ers this is somewhere near 46 inches…which led me to produce the following thought experiment:
[rethought/updated, the Brachistochrone or cycloid is more important than a circle alone for rollers, jumps/ramps, and descents, however, it is the circle that creates a cycloid]
Parabolic Jump/Projectile Trajectories