Same thing happened to me a few years back, but I was on a motorcycle and hit the dog. Dog was DOA and I was out a 10k motorcycle after the crash. Dog owner tries suing me and my insurance company counter sues. Depending on the state and county/city rules dog owner is responsible for all damages caused when dog is not controlled (leash, kennel, etc.). I won the suit easily and dude's insurance had to pay for everything.

Even if the guy is a whack'o file a claim against him and at least get your bike fixed and a little extra money for personal injury,etc... If whack'o bothers you get a restraining order.

Joe