Lake Pillsburry is one of the closest dirt riding places from the Bay Area. Well, it's not that close but when you're there you have a very large number of options for riding. The file attached is a good suggestion for a weekend there, everything (besides climbing Mt Hull from the South) being easily doable on a GS-like bike. I left the track going West even though it's a dead end for 2 reasons: it was fun anyway and at least now you know for sure that it deads end . If you want to see some pics here the ride report.