I have a full-on mountain bike for my commuter ('97 Breezer Storm). I changed the cassette so it has taller gears, a rigid fork and 1" slicks. Otherwise it's all mountain bike. I'll be the first to admit it's not the fastest bike around, but I like the comfort it gives me for my 20-mile one way commute which I ride 4-5 times a week. The longest ride I did was 126 miles and take it on 40-60 mile rides about once a year. I don't take it offroad as I have another bike for that......