Everyone here is on the money when it comes to spinning and seat height. I only wish to add one more way to cope with aching knees. ASPIRIN (or its equivalent) can keep a minor ache from turning into a big one, by reducing inflamation, which itself can cause further irritation in an ugly positive feedback loop. Take a couple of aspirin before you hit the hills, and boy what a difference it makes (and it worked even before I turned 50).