It's the most famous 24-hour mountain-bike race, held in the mecca of the sport, which is why 4,000 racers and spectators swarm this 15-mile loop every October. "The course alternates between rocky and really sandy," says Chris Eatough, six-time 24 Hour Solo World Champion. "So go with a wide tire—2.2 or 2.3 inches—since tread doesn't do much in deep sand or on rock anyway." And don't forget about comfort: Soft saddles, cushy suspension settings, and warm clothes for the freezing nights will make the course a little less painful. $150; grannygear.com