When I was in High School, my gf suggested I try spinning with her. Me..the big football player wasnt sure about this..but i did anyways. It was insane. The instructor was so insane...but it really really works you out good! Our session was about half an hour, but, it really kicked my butt. I say, its a GREAT cardio workout, and it will tone your legs. You really really feel it in ur hamstrings, glutes, quads, and even calfs. There's different classes for different experience levels. It's a lot of fun as well!