I commute when its 100+ in the morning and 110 in the afternoon and commute only five miles, yet I sweat and stink like I've just come off the TDF (there is no such thing as a "sub-perspiration pace" here). I wear baggy shorts and a t-shirt... with lycra shorts and jersey under them to keep the sweat at bay. I change into normal undies and a clean shirt (after a wipedown with washcloth) when I get to school and spend the next hour reading (re: cooling off.)