Critical Mass is a mass bicycle ride that takes place on the last Friday of each month in San Francisco starting at 5:30 pm at Justin Herman Plaza (foot of Market Street) and in cities around the world. Everyone is invited. No one is in charge. Bring your bike.
Please Note: Critical Mass tends to practice extreme bike power by taking to the streets and riding in the car lanes causing endless annoyance to motorists.
In San Francisco especially, this event can get HUGE. Consider this is fair warning to stay away from driving in the downtown SF area on the last Friday of every month.