i love spinning! and mainly because i can tailor it to my own needs and condition. every so often i'll find an instructor who feels it is her place to tell me that i haven't added enough tension. but i know my surgical knee better than she does. the same instructor also likes to do things where she wants you to only pedal with one leg. again, i pass on that. so far, she's not said anything to me if she has noticed. i figure that i don't do that on my road bike, so i don't do it on my spin bike. and i'm sure my knee surgeon would be OK with that too.