I started spinning a month ago. It's certainly easy enough to tell the spinners from the cyclists. Some of them are amazingly aerobic and can spin at ridiculously high cadence. They can spin at like 100+ RPM out of the saddle too. But they have those skinny legs

The biggest adjustment for me as a cyclist was learning to recover by spinning and not by coasting downhill. I find that the climbing I do in spin class really helps me on the road and that (once I got a portable heart monitor) I need to push harder in class to get my heart rate p to where it is on the road bike. Also, on the road I take like 30 minutes to warm up. No such luxury in spin class.

Women in spandex are kind of interesting too.