I commute to school etc and carry a lot of crap. Often a laptop, text, lunch etc etc. If I were to take my bag it weights often around 25+ lbs. This just is not comfortable to bike with in my experience. Thus, I have a cross bike that is the best of both worlds. Relatively light and can sport a nice strong rack to hold all my stuff. Win win and the best way to go for commuting in my situation.