Carry your cell phone and practice using it with one hand, practice gives you options. Stress shuts down options. Practice lets you take pictures of the car, driver, license plate. Then call 911, forward your information and pictures to the cops. Bully's rely on being hidden, shine a light on them.
Also, gang up, find a buddy, ride together, make numbers count on your side, or if you have to ride alone, find bike paths and stay on them.
Carrying a gun means you've studied all applicable laws related to the display and use of deadly force, if you haven't thought through what you can and cannot legally do, that gun could be the worst thing you ever touched. Life is not "Gunsmoke" and you're not Marshall Dillon.