It comes off the back. The batteries have lasted longer than I need them every time. The free-hub is a standard Shimano/SRAM 9-10 speed type. Then the next day, extremely spotty sound. Don?t buy if you are expecting good arch support. Anytime I shop Nike, I never have to worry about whether they will fit. I dislike the fact they are not as easy to put together as whats mentioned and I really like the size of the product. We?ve been using them for several years. Suggestions: It would be pretty nifty if there were some sort of carrying bag included for taking this on the go to have an all in one recording setup with you on the go. Yet another company that just cant handle the simple concept of Mouse Software.