SFist Photo: Commute Clot's 15th Anniversary Tonight

How will you react to today's larger than normal Critical Mass? With aplomb, as these two did? Or with rage, ala many many Chronicle commenters

A small goup of San Franciscans started an international trend about fifteen years ago when they participated in the first Commute Clot bike ride. Now it's called Critical Mass. What do you call it? Well, try to keep your cool. Lots of people will be coming to ride their first Mass tonight so things will be better/worse than normal. You should try it once in your life, anyway. If you want. Starting at 6:00 PM at the foot of Market Street.