Depending upon the circumstance I'll either try to stay just ahead of them so they think they can catch you, but to get them some distance from their starting point, which hopefully is an irresponsible owner Or if the opportunity arises, I must admit to freeing off a foot and swinging it back to lash out at any dog that starts chasing me on my bike.
It's the stupid gits with the reel leads which really piss me off. I thought there was a brake on those things. Use it! If you can't control your dog, put it on an old fashioned short lead and choker. That way the dog can't go far and strangles itself in the process.