There are new bike paths in SF, which despite its hills is a very bike-friendly city - the perk of these trails that go along the bay is that you don't have to cross any traffic, so they're good for skittish or inexperienced bikers, or children.
One of the most popular trails is the ride from the Ferry Building to Sausalito via the Golden Gate bridge. You can find printable maps on the official site for the Bay Trails.
Bay Trails Bike Path
recommendation by johnny- recommendation by bon-vivant
recommendation by goose
