Critical Mass is a cycling event typically held on the last Friday of every month in cities around the world where bicyclists and other self-propelled commuters take to the streets en masse.
While the ride was originally founded with the idea of drawing attention to how unfriendly the city was to bicyclists, the leaderless structure of Critical Mass makes it impossible to assign it any one specific goal. In fact, the purpose of Critical Mass is not formalized beyond the direct action of meeting at a set location and time and traveling as a group through city or town streets.
Critical Mass rides are self-organized, non-commercial and non-competitive, and they operate with diffused and informal decision-making, independent of leaders. They are mostly unofficial, foregoing permits and official sanction from municipal authorities. Typically, only the meeting place, date, and time are fixed. In some cities, the route, finishing point, or attractions along the way may be planned ahead.
Critical Mass rides have been perceived as protest activities. However, Critical Mass participants have insisted that these events should be viewed as "celebrations" and spontaneous gatherings, and not as protests or organized demonstrations. This stance allows Critical Mass to argue a legal position that its events can occur without advance notification of local police.
Critical Mass rides vary greatly in many respects, including frequency and number of participants. For example, many small cities have monthly Critical Mass rides with fewer than twenty riders which offer safety in numbers to cyclists in those locales, while on the opposite extreme, in what have been the largest events using the name Critical Mass, cyclists in Budapest, Hungary hold only two rides each year on 22 September (International Car Free Day) and 22 April (Earth Day).
The 'Budapest style' attracts tens of thousands of riders. The April 20, 2008 Budapest ride participation was generally estimated at 80,000 riders.
Critical Mass differs from many other social movements in its rhizomal (rather than hierarchical) structure. It is sometimes called an "organized coincidence", with no leadership or membership. The routes of some rides are decided spontaneously by whoever is currently at the front of the ride, others are decided prior to the ride by a popular vote of suggested routes often drawn up on photocopied flyers.
The term xerocracy was coined to describe a process by which the route for a Critical Mass can be decided: anyone who has an opinion makes their own map and distributes it to the cyclists participating in the Mass. Still other rides decide the route by consensus. The "disorganized" nature of the event allows it to largely escape clampdown by authorities who may view the rides as forms of parades or organized protest. Additionally, the movement is free from the structural costs associated with a centralized, hierarchical organization.
