Sorry for the delay in replying to this, but here are some options for after you leave San Francisco. These trails are east and north east of San Francisco, so could easily be included in your trip north.
Heading east out of the city on Highway 80, I would suggest going past Sacramento and trying a few trails in the Auburn area. Clementine is a good ride, with a nice connector trail to the Foresthill Loop:ClementineClementine-Foresthill ConnectorForesthill Divide Loop
After leaving the Auburn area, I would suggest heading north on HWY 49 to Downieville, which has lots of places to camp or stay, and is a very bike centric town. The summer population basically revolves around mountain biking and the trails are world class. The main ride would be the Downieville Downhill, but there are other rides in the area that are great as well. Many people book a shuttle from town to the top of the mountain and ride back, but there are certainly trails to ride to the top, if you choose. I have had great luck using [url]http://yubaexpeditions.com/]Yuba Expeditions[/url] as my shuttle service. They are always courteous and knowledgeable with reliable shuttles.
The most famous trails are:Downieville Downhill1st, 2nd, 3rd Divide trails
I like to add in the Pauley Creek trail option from the drop off point (Packers Saddle):Pauley Creek
If you want to go a bit further east before you head north, you shouldn't miss a few of the Lake Tahoe area trails, which are some of the best in the country:Tahoe Rim TrailMr. Toad's Wild RideFlume Trail
Northstar Resort is located in North Lake Tahoe and is a decent DH park with great lodging:Northstar Resort
I hope you have a great trip!