2-wheeled sideshow blocks SF-bound traffic on Bay Bridge Sun afternoon. “About 75-100 bikers swarmed cars from behind, some riding on their back wheels only, then proceeded to arrange in a solid line across all lanes before slowing down & stopping altogether,” witness tells.The bikers could be seen performing donuts with smoke from the burnt rubber filling the air. 

Some revved their engines and rode around in circles as they tested the patience of other motorists who were powerless to do anything but watch.

Similar incidents this past year. Traffic was disrupted for about two minutes before resuming once again