A bike counter installed on San Francisco's Market Street yesterday counted 3,231 two-wheeled commuters on what was Bike to Work Day. Market Street is said to be the busiest biking street west of the Mississippi. Copenhagen has the busiest bike street in the world, where over 10 times that number of cyclists use it daily. That in a city with a population that's some 20 percent smaller than San Francisco. How long will it take San Francisco—birthplace of Critical Mass—to catch up?