This points up some unclarity on the purpose of the gizmo we're musing
about here. One purpose seems to be:
Put a spring under the seat to promote pogo-sticking.
while the other seems to be:
Put a spring/shock under the seat to smooth out the ride.
I think the difference is essentially whether or not you use a shock to
damp (stop) oscillations. Which one are we trying to achieve?
Two other thoughts:
1 /Why/ did George's knees hurt?
2 Any vertical movement of the seat changes the distance to
the pedals. Would a moving seat compromise control? Or is it
a question of degree, to be tuned through trial and error?