The real adventure is trying to pee off of the bike in a road race.
The pros often have to do this, and even us lowly amateurs occasionally find themselves in a long enough race that it becomes an issue.
In the State Championship road race a few years ago, I thought I'd just about die if I didn't take a leak, and we had perhaps 40+ miles remaining. I think I tried 3 times, immediately following the feed zone, when the pack was taking it a little easier.
I'd drift to the back, roll up one leg of my shorts, and try to let fly as I coasted along. Apparently the car with the USCF marshalls following was enough to shut down my functions, because I just couldn't get things to work, and spent the remainder of the race in agony.
I did manage to be the first guy through the last turn, in hopes of setting up a teammate who was in the process of winning the Cat 3 Cup that season, but then all I worried about was getting across the line w/o pissing my pants.
So the bibs were the least of my troubles.