I agree with top-end spinning with minimal resistance being BAD for knees. I am a Bio with a bit of a cycling background and do biomechanical troubleshooting in persistent overuse-type of cycling injuries to assist in final bike setup. Some of the issues we have identified after tracking a lerge group through several years are: - There tends to be an increase in Anterior/Posterior (Forward/Backward) instability in the knee of cyclists who do a lot of spinning - These changes seem to be linked to increased laxity in the anterior cruciate ligament in the knee - It seems to be more linked to the type of class (i.e. full out spinning, high speed stand/sit, low resistance work), rather than volume of spinning Solution: Choose your instructor/class better...
