I haven't been bitten by a dog on my bike yet, I can usually outrun them if I go into a dead sprint.

If the sprint doesn't work I resort to a kick in the face with my shoes. First kick is more of a tap with the outer side of my foot, second kick is a short blow to the chest, just enough to knock the wind out of them.

Sorry to all you dog lovers, but the kick does considerably less damage than if I were to fall on them.