:Vocalo.org

This Friday marks a big milestone for a big bike ride: Chicago's Critical Mass turns ten years old; on the last Friday of every month since 1997, folks have been gathering at the Picasso statue in downtown Chicago to go for a ride together. Recent rides have attracted as many as 3,000 bicyclists-- enough to stop a lot of car traffic-- and the Chicago cops intervened to re-route the last one.

So what do you think? Is Critical Mass an awesome rolling party? A godawful pain in the neck for drivers just trying to get home on a Friday evening? An effective political statement about the joys and necessity of going green for transportation? Or an obnoxious gesture that alienates as many folks as it reaches out to? All of the above?

Call with your Critical Mass stories, good or ill (or both): 888-635-1112. Leave your story as a voicemail-- I'd like to put as many of these on the air as possible.

In the meantime, we'll have a report from the World Naked Bike Ride, an entry from Matthew Purdy's audio diary about his current quest to bike across the U.S.A., Kim Morris's awesome "Crash Stories"-- tales of life, love and pain as a bike messenger-- plus sounds from a recent Critical Mass gathering, and, for equal time, some interviews from a gathering of car-lovers in Crown Point, IN.