Come summertime and melting snow, Mammoth Mountain  transforms from a ski resort to a mountain bike mecca. The Mammoth Mountain Bike Park (1 Minaret Rd., 800/626-6684, www.mammothmountain.com/bike_ride , daily 8 a.m.–6 p.m., $10–39) spans much of the same terrain as the ski areas, with almost 90 miles of trails that suit all biking ability levels.
The park headquarters sits at the Mammoth Adventure Center (1 Minaret Rd., 800/626-6684, June.–Sept. daily 8 a.m.–6 p.m.). You can take your bike onto the Scenic Gondola and ride all the way to the top of Mammoth Mountain , then ride all the way down (3,000-plus feet) on the single tracks. Be sure to pick the trails that best suit your fitness and experience level!
Several other major lodges offer rider services, including the Village at Mammoth, Juniper Springs, the Panorama Lookout, and Outpost 14. If you value scenery as much as extreme adventure, pack your camera and plan to rest at the various scenic overlooks throughout the trail system.
If you need to rent a bike (and to buy park tickets), go to the Adventure Center or to the Mammoth Mart at the Village (6201 Minaret Rd., inside The Village, 760/934-2571, ext. 2078). Both locations offer new high-end bikes for adults and kids. These shops can also help with parts and repairs for bikes you’ve brought up with you, and sell accessories.