Quote Originally Posted by Wasp View Post
I have a spin bike and at 90 rpm I don't bounce, so there must be something off with the fit? Or is this bouncing caused by being inexperienced? Or both?
A spin bike is much heavier than a rideable bike, and it doesn't have suspension (in the form of tires) between the frame and the ground, so it takes a LOT to make one bounce. As in, a WHOLE lot. (Pick your rideable bike up a couple of inches off the ground, be ready to catch it when it bounces, then drop it and watch it bounce. Now try the same thing with the spin bike, except don't bother being ready to catch it, because it isn't going to bounce.)

It's possible there's a fit issue, but it's more likely just a matter of practice.