I am not spinning fast at all - indeed am still going fairly slow when it starts (I've only had my bike for 2 weeks). I DO know that one leg is stronger than the other - and my podiatrist suspects that one leg is shorter than the other. I do not notice this on the spinning bike in class, but that is not the same.
The trainer I am working with on conditioning for cycling (and who is a life-long avid cyclist and mountain-bike racer) isn't sure that it is a leg-strength issue - but of course he hasn't been present when it happens. I will ask him to show me the spinning drill with one leg - I do not have an indoor trainer and am trying to wait until next winter for that if I can. (Personal training sessions and new bike support has tapped me out for now![]()