What happened in San Francisco, where a bike commuter struck and killed a pedestrian, is a tragedy for both sides. I'm all for bicyclists sharing the streets with cars — obviously it's better for the environment — but bicyclists should be tested and licensed the way motorists are, and their bikes should carry license plates too.
Maybe that would help curb the thoughtless element that blows through stop signs and red lights and blithely crosses streets mid-block. It might even stop the guys who face their bikes the wrong way in traffic lanes so their biking buddies can get a head start over cars.
It is wrong to demonize all cyclists for the actions of a few. Bicycles are wheeled vehicles and must yield to pedestrians just as cars must do. The cyclist accused of hitting and killing the pedestrian should be prosecuted just as if he were behind the wheel of a car. He may learn to show more concern for the life of another human being than for his helmet.