I'm a long-time outdoor cyclist and really couldn't understand the appeal of these classes. Cycling = spending a lot of great time outdoors, fresh air, quiet space in your head, getting somewhere interesting with great sights along the way. So the idea of cycling indoors, in a sweaty hot room, with someone else's music blaring, sitting on someone's else's equipment, going nowhere like a guinea pig for an hour, seemed perfectly ridiculous to me. Why would I do it, if I could get on my own bike and go for a ride anywhere here in the SF Bay Area? But we had a particularly rainy winter and the spinning classes at the gym were free and at 6:30am, perfect time for me, so I gave it shot.
I'm sold, with a few reservations. The benefits of the intense conditioning people have already talked about, and it's great to get my cardio out of the way early in the day, for metabolic and schedule reasons. And the equipment is pretty darn comfortable and feels like a real bike--that sort of surprised me, but I'm glad of it. But on top of that, our classes are run by real cyclists, so there is a fair bit of extremely useful technical drilling that goes on which has definitely improved my regular riding technique and has done amazing work on increasing my strength for all the hill riding we do around here in the Bay Area. You can really go all out indoors--sprinting, standing, going to the limit of your conditioning--without having to worry about safety concerns, road conditions, cars or getting home. So that's a BIG plus in my book.
Reservations: Some of the female instructors seem to feel they have to prove their masculinity, which is a little hard to take at 6:30pm. The male instructors are more laid back in personal style but just as intense about the workout. Also, sometime the music can be pretty tough to swallow--one memorable night was listening to Philip Glass's Satyagratha for an hour, not what I would call cycling music. And not a whole lot of instructors really have the taste for the kind of Euro-techno-trance I do. But I've made my own playlists and do my own thing about twice a week, as well as going to 2-3 classes a week, on top of my regular cycling, so it's really added an important cross-training dimension to my riding.