When I was still at MSU, Gavin and I met a guy at Cafe Latte who worked as a stuntman on some big studio films. The thin was, the guy was about 5'8" and was built like Steve Buscemi. Most of the stunts he wound up doing, he told us, were things like riding a bicycle or running down a hill: anything *less* stressful (or more camera-intensive) was done by a stand-in. If the *stand-in* fell down or twisted an ankle, they would lose days of shooting and tens of thousands of dollars: hence the ersatz stunt man.