[quote=”Use a roller that is constant diameter and NOT one that is thinner in the middle. People do that in the belief that it will keep the bike central on the roller. It has exactly the opposite effect, and the bike will slew sideways !
Yes indeed. The item being driven will always track to the “high point” until a certain point (of slow speed/wide driven component) is reached then it tracks to the low point.
Something as fast/narrow as a bike wheel will definitely go to the high point.