West of San Rafael and Fairfax, the Tamarancho Boy Scout Camp has an excellent 6.7 mile mountain bike singletrack loop. The loop climbs through pine forest coming from Fairfax and then rolls through scenic meadows.
There is a new purpose built side flow trail with stunts called the Endor Flow Trail. The Endor Flow Trail is a one mile long trail with berms and rollers through dense redwood forest.
To reach Camp Tamarancho from San Francisco, head north on US101 to San Rafael and use Exit #452. Head west on 3rd Street which turns into 2nd Street. Veer right heading west on Sir Francis Drake Blvd to Fairfax. Park in town at either Java Hut or Fairfax Cyclery. Start riding west on Sir Francis Drake Blvd to Olema Road. Veer left on Olema Road briefly to Manor Road. Turn left on Manor Road and then Right on Rockridge Road. Veer left on Iron Springs Road heading up for about 0.75 miles. The trails start on the left. Make sure to pay for your daily use fee permit.
Tip - After a long mountain bike ride at Tamarancho Boy Scout Camp, make sure to head over to the Gestalt Haus in Fairfax for a cold drink!
Overall, Tamarancho Boy Scout Camp is the 106th most popular mountain bike trail of all 132 mountain biking rides in California.