Just a reminder that today is Critical Mass, wherein bike riders pedal up Market Street. And other places. Seeing as how it's an unseasonably warm day today, it's bound to be crowded so please use extra precaution, drivers and riders. Remember, the right-of-way pecking order is as follows: kittens, old ladies in wheelchairs, pedestrians, cyclists, joggers, and then automobile drivers. Have fun. The action starts at 6 p.m. at Justin Herman Plaza, Market at Embarcadero.