Not that I don't wholeheartedly endorse nonviolent conflict resolution methods, but I find that if I give "them" a fight, they often do back down. Aggression may be a fairly common response, but very few of the people who resort to it are willing to stick with it - they use it *because* it deterrs response. After countless honks, screams, "get the **** off the road"s and death threats, i finally gave in, and learned first hand that when most people, even when staring you in the face threatening your life, would not "step out of their *%$&@!ing car and say it to your face" if there were a gun to their head, especially if you've just chased down their car over a few km on a bike. Childish bullying will only be encouraged by conceding to it. By pulling aside, speeding up, running away or getting on the sidewalk we only prove that aggressive threatening behavior works. If you can prove otherwise with a smile on your face (nothing's more pathetic than somebody choosing to lean on their horn for 2 blocks rather than change lanes), then so much the better. But one way or the other, don't reward bad behavior.