Noble Canyon singletrack in Cleveland National Forest (40 miles east of San Diego) is a great half-day, 14-mile loop with 2,000 feet of elevation gain. Take lots of water unless you want to use your brain pan as a skillet later on.

To get there, take exit I-8 at Pine Valley and at the nearby gas station buy your Adventure Pass. Take old Route 80 two miles to a right on Pine Creek Road. After about three miles you'll see the Cleveland Forest parking lot. The Big Noble Trail, as it's signed, goes three miles to a sign pointing to Laguna Mountain. Up you go—a real gruntfest. At the top you'll enjoy a challenging singletrack downhill, first through chaparral, sage, and rubble, and then some boulder sections with stream crossings.

This is a tough trail! At the bottom you can opt for a road return or simply go back the way you came.