They drew laughter and applause from startled by-standers as they whisked east along Bloor Street West, and down Yonge Street, ringing bike bells and wearing little, and accompanied on trumpet by a fellow cyclist.

It was Critical Mass-an event where cyclists meet up at the corner of Bloor Street and Spadina Avenue at 6 p.m. on the last Friday of each month and ride around downtown-but with a twist. Following last Friday’s afternoon ride, bikers reconvened at 10 p.m. for Critical Ass, a clothing-optional reprise.

The term critical mass comes from an early-90s documentary on cycling, which described a common scene encountered by cyclists in China at busy intersections that lacked traffic lights. Cyclists steadily amassed at the intersection, waiting to cross, until there were enough of them that they could cross together as a swarm, forcing cross-traffic to yield.

“CM is about asserting our right to the road, not denying others their right to the road,” says Michael Bluejay’s Critical Mass website, which tracks the phenomenon’s worldwide spread. The first critical mass ride took place in San Francisco, in 1992 (“CM is an idea and an event, not an organization,” the website stresses.)

Friday night’s Critical Ass drew twenty-odd riders in varying states of undress. Among them, a colourful cast: two bikers wearing angel wings and the trumpet player of a local ska band. And although some riders seemed at several points on the verge of contradicting Bluejay’s dictum, drivers took the traffic disturbance in stride-with one noisy exception on Bloor Street, that is.

“Tell your little queerish friends to get the —- out of my way!” an angry motorist told The Varsity, feverishly honking his horn.