That dog WILL chase you again, and you don't want that to happen with your grandson along. Here's a tip on controlling problem mutts...
Fill a kids water pistol with ammonia and keep it handy on your bike, when you are chased again, let em have it. You don't even have to hit your target, a dogs
nose is so sensitive, that just a spray in the air will turn that dog into a pussy.
I used (USED) to have a problem with a neighborhood mongrel, now, that mutt runs away from every bike that rides by. I own a dog and love it, but all he chases
is his food bowl.