There's an inaccurate assumption at work that assertiveness is likely to lead to violent confrontation. In fact, being calmly assertive is often the best way to head off confrontation, because it challenges the power dynamic that is making the confrontation possible. When someone is bullying you from the safety of a tonne of metal, they are usually doing so because they are expecting you to be intimidated and to let them have their way, and also because they can abuse you as they pass and then not stick around to face you. You'd be amazed at how unscary the most burly, loud-mouthed motorist usually becomes when an unarmed cyclist taps gently at the window and makes the winding-down sign. Defensive and rude, sometimes, but not scary. All you need is to take away their advantage...