Worldwide Critical Mass Hub
Sports, Cycling, Commuting and Advocacy, Critical Mass - Worldwide Critical Mass Hub. Comprehensive guide to local Critical Mass sites in cities all over the world.
http://criticalmassrides.info/
Boston Critical Mass
Sports, Cycling, Commuting and Advocacy, Critical Mass - Boston Critical Mass. Bike advocacy organization.
http://www.bostoncriticalmass.org/
Chicago Critical Mass
Sports, Cycling, Commuting and Advocacy, Critical Mass - Chicago Critical Mass. Features news, events and information on the group's activities, press releases, annual art show, and contacts.
http://chicagocriticalmass.org/