Don't forget that the main road through Blackhawk has a maximum speed limit of 20mph. Unless drivers are speeding, they wouldn't be slowed that much by a lot of cyclists -- or at all by many. I read somewhere that one of the first cyclists pulled over for this stupid law thought she was being pulled over for speeding.
They claim safety but they've had no bicycle related safety incidents in Blackhawk in years. The 20mph speed limit probably has a lot to do with that.