It's the kinder, gentler version of Critical Mass.
The rules are surprisingly considerate. "Stay in the right lane. Stop at red lights. Leave nothing and nobody behind," says the description. "Roll past conflict."
That's a far cry from Critical Mass, the generally ungoverned monthly assemblage of bicyclists. In the past, those events have occasionally turned violent when bicyclists block intersections, delaying cars, buses, taxis, and trains just to prove that they can.
Friday's route is an extensive tour of the city, and features a few challenges. It starts at 8:00pm from the ballpark, then swings around Embarcadero to Pier 39. from there, it swings to the side of Fort Mason, then begins a grueling climb up Russian Hill.
After a regroup at the top of the hill, it'll sweep down Pacific Ave towards the Richmond, then down 8th into Golden Gate Park. After a quick circle around the Music Concourse, it'll cruise down the Panhandle and then face one more climb, this time towards the Full House Houses, and finishes up at the Asian Art Museum.
The theme of the ride is "Birthday Party," so bring your paper hats (to be worn on top of helmets, of course) and your noisemakers. A mobile sound system will keep the energy up for the duration of the ride. And after those hills, a little energy-boost will be sorely needed.