Near Danville east of San Fran in the Mount Diablo State Park, the Mitchell Canyon Trail can be combined with fire roads to form a strenuous 12 mile mountain bike loop up to one of the worlds most panoramic summits (over 3,000 feet vertical). The trails are of crushed granite with great drainage. Check out the side trail along Shell Ridge. The park is located near Danville off US 680 at the Diablo Road exit.
Overall, Mitchell Canyon is the 29th most popular mountain bike trail of all 132 mountain biking rides in California.