So the gym I go to just remodled and added a studio with spin bikes and a computer kiosk thing hooked up to a large projector that has spin classes that have you riding through the mountains, Ireland, yada yada. Instuctor narrates and tells you the cadence, resistance, and to stand up, sit down, ect. I've done a few of these now...........Holy balls it's a good workout! I do my fair share of biking, but these are intense. If you've got an injury and can't run, but can pedal a bike, or just want a good workout give a spin class a try. I'd never done one before a few weeks ago. First time I did one, I couldn't finish it. Now after a couple different workouts, I'm still in a puddle when it's done.