I've recked on a bike so many times... I used to race and it was crash or win, whatever came first. I was a state road and crit champion. It's not if you are going to crash, it is when... Needless to say, even Lance crashes (the best Tour de France cyclest ever). I gotta say that crashes on a mountain bike can be much worse than crashing on a road bike. The road bike usually slides out from under you and you end up with severe road rash. Crashing on a mountain bike usually involves hitting an unmovable object like a tree, boulder, rock strewn path. Good luck with it and tell him to get on the trainer and put the broken appendage in his compression short's waist band.