I've started taking spinning classes in hopes of building bike endurance, because I have the ultimate goal of doing a sprint triathlon that has an 11 mile bike ride component. I am trying to track my mileage in a training log, and I am wondering, how should I record spinning? Is there any way to estimate what the equivalent distance would be for a 1 hour spin class? The spin bikes don't have any mileage info on them...

Also, please tell me this will get easier. The rest of the class is climbing away and I have to sit in the saddle and lower the resistance and catch my breath after a minute or two. (I feel like it will be a banner week when I can follow the instructions for the entire class!)