Can you camp in the area around the trailhead? I know you don't really want to go on an overnight trip every time you want to mountain bike, but it is a fun option. It's the kind of sacrifice you have to make to be car free I guess. I've been tempted to get a beater car to keep for backpacking, climbing, and such, but at this time it is hard to justify the cost.
Are any of the trails accessible by commuter train?