From sfbike.org:
This ride will explore a big slice of the city that you’ve probably never seen before, south of the Mission District and Bernal Heights. The ride will introduce you to diverse the neighborhoods, cultures, parks and vistas hidden away in San Francisco’s little known southern side and climb a few hills along the way.
SF Bicycle Coalition recreational rides are free for SF Bicycle Coalition members (a $5 donation from non-members is appreciated); rain cancels rides.