This is it, the Birthplace of Mountain Biking, on Pine Mountain (not Mount Tam, sorry Wiki) near Fairfax, California in bucolic Marin County. Read all about it:
The first downhill time-trial race took place in Fairfax, California on October 21, 1976 on a fireroad now referred to as Repack Road, due to the need to repack hub bearings after a descent (the hub brakes used at the time would overheat, causing the grease within the hub to break down). Ten riders descended 1300 feet of Repack in about 5 minutes; the winner, Alan Bonds, was also the only one to make it to the finish line. The first bikes used for descending were known as “clunkers” or “paperboy bikes”: coaster brake cruisers using balloon tires first imported to America by Ignatz Schwinn. By 1979, two organizers and competitors of the Repack downhill, Charlie Kelley and Gary Fisher founded the company which named the sport, MountainBikes.
It looked like this. Gary Fisher, the Founding Father of Mountain Bikes, still holds the speed record with a time 4:22. (He also caught 36 in a single lunch break, but that’s another story.)
So, here it is. From top left to right middle, above the Meadow Club Golf Course and Lakes Bon Tempe and Alpine. Click to enlarge. Or, see a bird’s eye view if you prefer.