Henry Coe is by far the largest park listed on this website and one of the remotest. While not all of it is open to mountain biking, its more than 130 square miles of total land area easily dwarfs any individual city around the Bay Area (like San Francisco, at 49 square miles) with the notable exception of San Jose. It features many excellent bike-legal singletrack trails, though it'll frequently make you work hard to get to them. Its fire roads are notorious for steepness.

This ride starts from the Coyote Creek Entrance. (If you can't find parking there, you might have to park instead at the Hunting Hollow parking lot two miles further south on the same road and bike up from there.) It climbs up to Wilson Peak via Spike Jones Trail. The GPS track available for download here actually reflects a mistake we made when I was doing this ride with a few of my riding buddies. Thinking we're turning onto a side trip on Timm Trail, we turned too early and ended up on a (probably illegitimate) unmarked trail instead. It was very rough in places and its steepest portion had drops that looked like it was made by/for hard-core downhillers, which weren't much fun scrambling uphill. So, I'd avoid following the GPS track exactly along that portion and would follow Spike Jones Trail instead (and then maybe take the real Timm Trail as a side trip, but I couldn't describe to you what that's like, since I've never been on it).

Once you reach the ridge top, you're rewarded with views in all directions, even if you don't see much more than neighboring ridges and valleys. Shortly after passing Wilson Peak, the route dives into Serpentine Trail, which is a steep singletrack descent. I found this trail to be quite a lot of fun, but the feeling was not universal among all of my riding buddies.

At the bottom of the valley, Serpentine Trail ends at Grizzly Gulch Trail, which is a fire road following the creek bed. Shortly, this trail starts crossing the creek multiple times, which was one of the highlights of this ride, in my opinion. During rainier times of the year, you might have to get pretty wet in this section. This is followed by a moderate climb along grassy hillsides to the intersection with Dexter Trail, after which (following a bit more climbing) Grizzly Gulch Trail starts its fun and technical descent that's also pretty steep in some spots (including one that features a short bypass trail). This trail is marked as a dirt road on the park map but this descent was no less fun to me than a singletrack.

One other thing Henry Coe is known for is the (seasonal) prevalence of ticks. So, before you ride here during tick season, you might want to educate yourself a little bit on the kinds of places where ticks may be found, what time of year they're most active, what's their behavior once they get on you, etc. Also, frequent stops during your ride to look for ticks on your body is highly recommended, and it couldn't hurt to wear bug repellent (though I wouldn't rely solely on that).

Finally, due to its inland location, the weather at Coe during summer months can get much hotter and drier than many other riding locations around the Bay Area. When you also consider its remoteness, the importance of coming prepared with extra reserves of water goes without saying, and planning your riding range carefully during the hotter months would be wise.