Well my boyfriend ran into a lady on her bike yesterday. But thats only because she had no common sense to NOT go infront of a car that's halfway in the street about to make a right turn.
Huge chance if you don't use a condom. Plus you should be worrying about std's. Has he ever been with anyone else? I think it is a horrible idea to not use a condom. If he doesn't want to use one then tell him you don't want to have sex because of the risk of pregnancy. It isn't worth it.