Interesting question. The university here (midwest) added dorms last year, so now we see a lot of bikes on campus, but I'd say 6 or 7 out of ten are men. I'm the only person I ever see commuting from off campus (6 miles, I'm female). Oops, take that back, I saw the guy from the LBS on campus, bet he commutes. I see people riding when I'm out, equal men and women, but they don't look like commuters. And really, there are very few. This city is very unfriendly for the bike commuter, though we have a great long path by the river, it doesn't usually help me go where I need to.