On a May 2007 visit to San Francisco, I found time to do some biking in the Golden Gate National Recreational Area, also known as the Marin Headlands.

Good maps of the area are available for downloading here: http://www.nps.gov/goga/planyourvisit/maps.htm

I rented a bike from Bay City Bikes near Fishermans Wharf and road across the Golden Gate bridge into the headlands. I can recommend Bay City Bikes; the staff was helpful and the premium bikes were trail-worthy. ... (more)