Henry Coe State Park is one of the biggest parks allowing mountain biking that you probably have never heard of. It is big enough to organize the "Hard Coe're 100", where you can ride 100 miles or km without repeating a single trail, point to point. The park is remote and desolate, even though the "Hard Coe're" coincided with the annual Henry Coe tarantula festival. In the desolation, a lot of your social graces become no longer necessary. Perhaps that is the draw of Coe for its faithful. It is a place where you can find some peace and quiet, or cut loose and be Bohemian, or suffer loudly with no one to hear.
To a roadie, 100 miles or 100 km doesn't sound very hard. But this is Henry Coe. Folks who ride here know it is a bit like the Tardis. It looks small on the map or GPS, but gets bigger when you actually ride it. This is also known to a few of us as “the Coe Factor”. It actually took me 2 hours less to do a 100 miles of trails in Mendocino than it took to do just a 63 mile ride in Henry Coe. The 63 mile ride (which I did) requires 13,000' of climbing, and the 100 mile Hard Coe're route (which some insane people did) has 22,000 feet of vertical gain! This is almost twice the amount of climbing in the famous Leadville 100 (aka Race Across the Sky), which is a paltry 12,000' of climbing. Leadville of course, is all 10k feet above sea level, whereas Henry C oe is oxygen-rich by comparison at 2k feet above sea level. However many trails are not well-defined and the route is unmarked making any adventure into Henry Coe a route-finding challenge.