The Format Project

Research on thriving formats of collaboration

Country of origin
San Francisco
People affected
Founded in
Chris Carlsson, along with Jim Swanson, Markus Cook, Kash, Joel Pomerantz

Critical Mass

“My life has been much richer and more gratifying, thanks to being part of the Critical Mass experience.”

How would you describe Critical Mass in one sentence?

Critical Mass is an "organized coincidence" of bicyclists in any given urban area who meet once a month to fill the streets with bikes as they ride home together, and by so doing, leave no room for cars in the streets they temporarily occupy on their ride.

Can you tell about how Critical Mass started? What was your motivation to help starting the first one in 1992?

Critical Mass grew out of a milieu of 20-30 daily cyclists who met informally over the preceding years. Over many months of beer- and pot-influenced conversations and brainstorming the idea emerged of gathering once a month to "ride home together." I was motivated by the endless 2nd class treatment I was subjected to as a cyclist on the streets of San Francisco. I wanted to turn the tables and for a brief time experience the city's streets as the dominant form of transportation, although as we began we had no idea how large it would grow, or if we would ever really fill the streets with bikes.

Can you explain how it works?

A good starting point is selected by some motivated pioneers and they begin advertising to other cyclists the time and day of the first ride. This is often done with strips of paper attached to bicycles with that information, and later, as the rides begin to happen, a lot of communication (in the early years) took place through the exchange of ideas and opinions on flyers and stickers of various sizes and shapes (we called this "xerocracy" as xerox + bureaucracy).

What are the key ingredients of Critical Mass' success? Why do you think it works?

The key ingredient for me is that Critical Mass exists for itself, and is not instrumentalized into some particular political demand, agenda, or goal. Insofar as that holds true, thousands of people have been able to embrace the experience and define it for themselves as they prefer. The only "requirement" is that one show up on a bike and be ready to ride, and ready to talk!

What are the rules of Critical Mass? If you had to select a single rule of thumb that is most crucial to its success, which one would you? What change in the concept, in the rules or in any other objectives would make it not work?

We came up with a series of "do's and don't-s" over the years that I think are still pretty good as "rules" though there is no enforcement mechanism beyond the social pressure that people in the ride can provide. This list is my "single rule of thumb" and as you can see, it's not easily reduced to one idea:

Critical Mass Do-s & Don't-s:
  • talk to strangers, bystanders, bus riders, motorists – welcome people to join us next time
  • help cars stuck in mass to exit to the right
  • stop regularly if you’re in front (no matter how slowly you think you’re going, gaps are opening up behind you)
  • stop at red lights when in front to allow the rest of the ride to “mass up” behind.
  • keep going in dense packs through red lights to stick together and keep it safe for everyone.
  • fill gaps; Critical Mass depends on bicycle density to displace cars.
  • remember that pleasure and friendliness are more subversive than anger and blaming.
  • race ahead to block cross traffic before the Mass has arrived
  • ride into oncoming traffic on the wrong side of the road
  • pick fights with motorists, even (especially) if they’re itching for one
  • fail to turn and twist through the city to make the ride more interesting
  • forget to smile and wave and talk to strangers!
  • imagine that you are morally superior just cuz you’re on a bicycle (you’ll be in a car again soon enough)
  • hesitate to tell other Massers what you think of their behavior, whether good or bad. Talk to each other!
  • forget – we are all responsible to make Critical Mass what we want it to be.

What makes people get engaged and involved in Critical Mass? What value does it bring to the life of its participants?

There are as many reasons why people get engaged as there are participants! Similarly, it brings a wide range of values and valuable experiences into anyone's life who rides in Critical Mass. Perhaps the most important is the way it permanently reshapes the individual's imagination of what city life could be. Once you ride in CM, you can never see the city's streets the same again, as you've tasted a little taste of a new life, a new way of being, a directly democratic and horizontalist experience that fills your senses even if you never thought about it before you arrived.

How do you get new people and organizers to join? Do you know whether new city organizers have attended any Critical Mass in person prior starting it in their own city? And where?

"We" don't "get" new people and organizations to join. Critical Mass has spread around the world in a classic meme form, passing through word of mouth, media reports, and phone calls among friends. There is no organization, and no recruiting, though I suspect there are individuals who felt so excited about it that they helped spread it to further places. Many people have ridden in Critical Mass in San Francisco and then gone home to start one in their own city, but since there is no organization, there is no record keeping, and everything is purely anecdotal. Even then, I would be hard pressed to identify anyone in particular who fits that profile.

What do you think of copycats of Critical Mass?

Great! All Critical Mass rides are copycats of other rides, and of each other. 

And when you explore the history you realize that mass bike rides are hardly new and date all the way back to the 1890s.

How do you feel about unofficial editions of Critical Mass?

There are only "unofficial" editions since there are no "official" editions!

What was the moment when you realized that Critical Mass is reaching out to a global community?

October 1992 when we got news of a ride starting in Poznan, Poland; a Polish friend in San Francisco had called his comrades there and encouraged them to start one, so they did on only the 2nd month of its existence.

How does the Critical Mass network work?

Not well. Very informal and accidental. Hard to organize in your own city, and even harder to organize across distances. Lots of collegial good will and friends show up from other places unpredictably. I have also had the pleasure of being an "accidental diplomat" in my many travels over the past decade, and have ridden in Critical Mass in over a dozen other places from Brazil to Mexico to Italy and Spain.

What is your relation to Critical Mass organizers? What is their role in their local sphere and in a global CM community? Are they connected to each other in any way?

There is no formal connection, and in our case in San Francisco, after 21+ years, there are simply no Critical Mass organizers at all! Some of us veterans have occasionally tried to organize thematic rides or propose routes, but we are often overruled in practice by the actual riders. Young people who have joined the ride in recent years have no interest in, and no respect for, those of us who helped start it a looooong time ago!

Do you think that the Critical Mass as concept, format or method can be adopted to other contexts? Have you seen any examples of it? In what fields?

Apparently not! Though it must be said that the 2011 Occupy movement in North America and Spain enjoyed the presence of hundreds of experienced Critical Mass cyclists who brought skills and experiences they developed in the ride to the occupy and indignado movements. Similarly, mass demonstrations in Brazil in 2013 also saw a lot of experienced cyclists participating in important ways.

What were the main obstacles you faced in the past years?

The relentless power of a society (and its government) owned and operated by the oil and car industries.

What was your best experience in part-taking in the founding and running Critical Mass?

I have met hundreds, even thousands, of amazing people in many countries. I have had a great time in San Francisco and many other places on countless beautiful rides through incredible urban environments. My life has been much richer and more gratifying, thanks to being part of the Critical Mass experience.

What is Critical Mass?

How it works

In the first years of the ride motivated pioneers started to spread the word about the time and location of the ride by ways of guerilla advertising, such as flyers and strips of paper. Nowadays with the internet being the main form of communication, it is easier to let people know about the events via social media sites. However, there are no official organisers nor set dates of the rides.

The purpose of Critical Mass is not formalized beyond the direct action of meeting at a set location and time and travelling as a group through city or town streets.

How it started

The idea of Critical Mass was to draw attention to how unfriendly the city was to bicyclists.

The ride was originally founded in 1992 by a small group of daily cyclists, evolving into a leaderless community of thousands. The ride is about the community, and about meeting people, rather than about a radical movement against car traffic.

"Social movements don't erupt from individuals, and individuals don't have ideas that are solely theirs. We are all shaped and influenced by our social conditions; our sense of what's possible and what we do about it is shaped IN ACTION WITH EACH OTHER. No better example exists of this larger dynamic than Critical Mass itself." (

How it spread

By word of mouth, media reports, and phone calls, without the need to organize or recruit. Twenty years after the first ride, there are smaller rides organized on the last Friday of every month, in over 300 cities, all around the world.

However, there are no real, professional organizers or any agencies that help the organization of the rides, so it is incredibly difficult to keep track of the flow of events. 

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