From SF Bike Coalition:

Eager to try biking with your kids, but not feeling up to doing it alone? Or just looking for a fun way to spend your Saturday morning with your kids? Join a group of parents and kids on a short, fun and comfortable ride from Duboce Park playground to Golden Gate Park playground and back again. Get advice from other parents and try family biking in a safe, welcoming group. We leave promptly at 9:15 am. You must be accompanied by a child. RSVP to kit@sfbike.org