Black Hills 100 (Sturgis, SD)
Credit: Pierluigi Benini

You've probably heard of Sturgis, South Dakota, a tiny little thing of a town on the northeast edge of the Black Hills National Forest. It's home to an annual motorcycle rally that draws about a half million people. Another big event on the Sturgis social calendar draws about 200: The Black Hills 100. The course isn't easy. Over the course of 100 miles, participants see temperatures in the 90s and the occasional mountain lion on the trail. Only 35 percent of racers finished in 2010, due in large part to heat and surprise thunderstorms. Good news for first-timers, though: Anyone who registers can run the race. It shouldn't be hard to follow the course. It's marked with buffalo skulls. [Late June; blackhills100.com]