On the last Friday of every month in San Francisco, a bike ride known as Critical Mass brings the city to a standstill. Whilst I was in San Francisco, it happened to be the 20th anniversary of it's inception, which presumably brought a lot more people to the ride.
Anyhow, the basic premise was that anyone that wishes to participate would meet at Justin Herman Plaza, aka the EMB, and set off on a ride around the city, with the route only being decided at the last minute to prevent it being shut down by the police I guess.
Interested, I decided to head down and catch the beginning of the ride, with some of the photos shown below. It was an amazing spectacle to see so many passionate cyclists in one place on such a wide variety of bikes and other contraptions. However, the ride supposedly does bring the city to a standstill in places, which is unfair to people just wanting to get somewhere, be it home after a long day or similar, so I'm not quite sure where I stand on it in general.