Not quite sure what you had in mind, but some I like to do are Mt. Tam and Lake Chabot/Redwood Regional.
At Tam, try parking in the Blithedale trailhead area, and ride up Old Railroad. There are some trail names I don't know, but you get on the road that eventually takes you to Hwy 1 and get on Miwok Trail to Tennessee Valley. Up a grunt climb to the overview and eventually down to Muir Beach. Hit the road, go toward Muir Woods then up Deer Park to the Pantoll Ranger Station. Across the street, catch a paved entry to a trail that eventually gets you up to Old RR again and either summit or head back to the car by heading down. If you follow these exact directions you will likely get lost! Consult a map or just know there are some great trails to ride in these areas and put them together to your liking. Some good stuff in the Headlands, too.
Chabot to Redwood Regional, East Ridge to West Ridge, some connectors to get you from place to place....another great area.
There's a start!