I've been spinning twice a week through the winter in order to be in some semblance of shape for an early spring century. Once a week I did the resistance machines and some core work to balance upper body workout with the spin workout on my legs. I guess it worked. I didn't finish the century, but rode further (43 miles) than I've ever done before, on a women's frame comfort bike, in headwinds. Not bad for an old lady. Now I'm still spinning twice a week because 1) I only just got my bike back from the ride, and now it's pouring rain here, 2) spin class is fun, 3) I learn a lot of technique that I know I still need to work on, and 4) I'm working on the psychological side of things, learning to tell myself when alone heading up a hill, that "Check your heart rate. See? You've worked this hard for a whole hour in spin class! Stay on it!" So maybe I'll learn to keep spinning on the road, keep spinning up hills ... learn the mental side of endurance enough to do a century ride on my own. Well ... it's a plan. We'll see if it works. But I'm sure the spin class helped. And I'm still getting better at it from class to class.