San Francisco: we party on Judgment Day, we party on drugs, we party on crooked streets and Big Wheels — and now we party on bikes. Hard. The San Francisco Bike Party slapped the scene silly at the beginning of 2011 with its monthly low-conflict costume-partied rides, invented in San Jose. (When does anything in SJ ever get props in SF? For this alone, SFBP deserves praise.) Call it the natural evolution of Critical Mass, call it an awesome Friday night with hundreds of velo-minded new friends, call it an excuse to make a hot toddy in a thermos. But SFBP riders call it one thing, and at the top of their lungs to boot: "Bike Par-TY!"

First Fridays of the month, 7:30 p.m., free. Check website for start location. sfbikeparty.wordpress.com

Photo by Erik Anderson