I am 51 years old and look very fit, but that belies the horrible joints I have. One day I was doing a moderate paced group ride with some guys who had been riding at a higher level for a long time. They knew I was fairly new to road biking. As I was riding beside one of the guys who is a triathlete, he asked how many gears my bike had. To that I replied "twenty." He then asked why I thought they were there. I paused and he said "Paul, I haven't seen you use but one." I had a computer with cadence. He asked what my average was. It was in the low 70's. He encouraged me to spin up into the 90's as an average and see how that worked. I did for the rest of that ride. I did for the following ride too, and much to my pleasure, my normally aching hips, knees and back felt much better. I am a reformed masher now. Spinning does my tired old joints good.