Salmon Falls is a well liked and often recommended singletrack ride along the shore of Folsom Lake. The ride is most typically done as an out-and-back route on one trail, Darrington Trail, though there are a couple of possible variations that could be added. It's a lot of fun and as scenic as you could reasonably expect any ride to be. The trail is not overly technical, though some stretches are more challenging than others. With moderate technical features and an unambitious amount of elevation gain, this ride seems tailor-made for riders of intermediate skill level (while brave beginners wouldn't have too difficult a time either), but I think that even very experienced riders would have a blast here. After all, there's no rule that says advanced riders constantly have to be riding "at nine tenths" in order to enjoy a ride.
Detailed description: bayarearides.com/rides/salmonfalls
I'm a late-start mountain biker who started biking in earnest only around 2006, in my late 30s. I've been riding around the San Francisco Bay Area regularly since then. Typically, I try to ride somewhere new on as many rides as I can. I'm also a bit of an obsessive record-keeper and I always use a GPS on my rides due to being a geek. As a result of this, after about one ride per week on average over these years, I've ended up with first-hand knowledge for most of the places around the Bay Area where one can do mountain biking. I've just taken a rough count and, as I write this, the list adds up to about 80 different locations around the Bay Area (without counting different trails and routes in the same park as separate).
My aim here is to help people in discovering and picking new places around the Bay Area where they might like to go mountain biking.