I've got a real sensitive spot for people being bullies so knuckling under just isn't in my nature. However an angry confrontation isn't usually a good idea either. How about a middle choice: Next time you ride by and he's acting like a fool, calmly stop, offer a big cheesy smile, and politely ask him if there's a problem. Sometimes people are like barking dogs...they don't really know why they're barking and if you talk to them they stop. At the very least you'll get a sense of his potential for violence in the future and can decide to change your route or keep annoying the crap out of him.