20th Anniversary banner

20th Anniversary

On the last Friday of September, 1992, a group of San Franciscan cyclists showed up on Market Street for the first ever Critical Mass. This leaderless ride became a monthly “organized coincidence”, and in the years that followed, spread around the world. Celebrating a shared sense of rediscovering urban spaces, Critical Mass riders cross borders and find common cause to have a good time on foot-powered wheels. These uplifting rides also challenge the use of city streets and the domination of cars and oil in our transportation system.

To mark the 20th Anniversary of the first Critical Mass ride, a group of enthusiasts has formed a Welcome Committee that is organizing a week-long celebration September 24-30, 2012. With great pleasure, we invite you to join us in San Francisco, California for our planned events, and we encourage you to get involved and/or create your own activities.

Dozens, hundreds, maybe a thousand friends from around the world will arrive here to help us commemorate this milestone. Friday the 28th is of course the big birthday, the Interstellar Critical Mass ride, which we hope will be a giant, crazy, awesome evening ending in a big party under warm skies.

español | deutsch | français | italiano | português | 日本の

Calendar of Events

A schedule of 20th Anniversary events!

Photo Contest!
Enter your photos taken during the San Francisco CM20 Anniversary Week in a contest! Winner to be announced on Saturday September 29th at the International Symposium at the SLIdESHOW SLAM (7pm-8pm)!
Please read the entry rules!

We are looking for volunteers to help with these events.


Looking for housing? Or have housing to offer? Hostels, camping, etc.


Looking for a bike? Have a bike to offer? Rentals, repairs, etc.


Information you’ll need!


A page to connect with other Critical Mass riders and visitors.

RSVP on Facebook

Email contact