I think Joey offers the best advice, obviously speaking from experience. Carrying a gun on a bike would be useless to downright dangerous. Your chances of being able to get to the gun and defend yourself are practically nil because you can't predict and prepare for situations like this. Plus, even if you were able to draw your gun, someone in the mob would probably have a gun and shoot you first. Or the mob would take your gun and shoot you with it. Or you would end up shooting an innocent bystander and go to jail. Or you would shoot one of the thugs and go to jail for using undue force. As Joey said, avoidance is the best policy when at all possible.