What Dina said! Spinning really helped me to get in good enough condition so that I could even consider biking... It took me several months before I could do everything in class and the instructor had to remind me from time to time to take it a little easier.

I wear bike shorts and technical athletic top. I do clip in but you don't have to. I do use a heart rate monitor because it keeps me honest, most don't.

Having fun is key - and do things at your own pace.