Road riding in the Bay Area - San Francisco

Yes, take the Bart into SF, fast and easy. I have been to SF a number of times on a motorbike but always wished I had my bike with me so I tried to keep in mind where the good cycling routes are and I'll give you some of my observations. As you're staying in Oakland a trip north to Berkeley would be nice for a shorter sightseeing ride since the city is fairly picturesque and Berkely University is worth checking out. Keep your wits about you in the poorer parts of Oakland though as crime is a problem but basically the same as in any poor section of a large city. SF again is generally safe but the southeast section of the city is pretty drab and higher crime but just trust your instincts. Also the Tenderloin district is a little seedy. Mostly sex shops, prostitutes, drugs. Not overly dangerous but would be last on my agenda. Traffic all around the city can be pretty heavy most of the time. There are plenty of other cyclists who ride all over the city and Marin County and demand respect from drivers so you won't be alone. "Critical Mass" for cyclists rights originated in SF and at a time when CM actually stood for something positive. Riding almost anywhere around the north part of SF is very interesting with it's unique architecture and individual neighborhoods but there are many very steep hills all over the city. You can take them on for the challenge or with some route planning most can be avoided. You can ride across the Golden Gate Bridge in a seperate lane from the cars so that won't be a problem. Sausalito is worth seeing for it's houseboats and wealthy fackers and from there go west to Marin and Muir beach by way of a small mountain road and if I can recall there are some forested areas and great views overlooking the ocean on your way to Muir beach. Anywhere along Hwy 1 near SF is very beautiful and I think, the best part of California. Plenty of info and brochures available on the net. Too much to list here. Learning a little of the history of SF really makes sightseeing far more interesting IMO. Each of the neighborhoods were formed by different immigrant groups who put their own style of architecture and culture in place (Russian Hill, Little Italy, China town, etc.) and the great earthquake of 1906 is a worth researching. Many photos and personal accounts exist from the quake. Bring a hefty lock and choose a parking spot wisely if you plan on stopping for a look around anywhere. Most bike shops have a bike route map that you can get either for free or cheap and possibly available on the net now. Hope this helps. Enjoy your trip!!

I'd google something like 'cycling club Bay Area' - should give you an idea of where the locals go. Maybe even some rides to join/people to hook up with.

If you're on the Oakland side of the bay, then take the BART to Walnut Creek and go to M. Diablo/ Morgan Territory.
http://bikeroutetoaster.com/Course.aspx?course=370672
On the Marin side this http://bikeroutetoaster.com/Course.aspx?course=370673 is a nice ride, just about to do it!
No problems taking the bike from Tiburon/Sausalito, in fact it's almost part of the ticket conditions.

head right across the bridge into marin county, and you will immediately hit some nice climbs to your left (admittedly i had started using a road bike about three months prior to cycling there, so they could be less steep than seemed at the time) ... and as someone mentioned going farther out there's mt tam (and farther out is muir woods, where we passed some cyclists as we drove up some twisty roads).

i was able to rent a decent bike from blazing saddles -- brought my own pedals. also may want to check for local cycling clubs (in napa, i contacted the local club ahead of time and then met up with them for a ride).