Critical Mass is an event that began in San Francisco in
the early 1990s and has since spread to hundreds of cities around the
world. It usually occurs monthly (sometimes weekly). as bicyclists
spontaneously come together to ride the ordinarily car-clogged streets
of their cities. Critical Mass focuses on the rights of bicyclists
and the rights of pedestrians on our own streets. It also brings
attention to the deteriorating quality of life -- starting with the
toxic levels of air and noise pollution -- that cars create for
cities.