What good is a ball bearing going to do? It'll just tick him off and he'll "give you a push".

He's just being a bully but he has the power to seriously mess you up. We ran into this kind of thing on motorcycles all the time. On motorcycles, there is sometimes an option to outrun the guy. On a bicycle; never.

I think your best bet is maybe to try to get other cagers to act as a witness on your behalf.