A few things come to mind:

If the same dogs are consistently coming out to "greet" you on your rides, call the Sheriff's department and report it. They WILL have a talk with the owners and there could be fines involved. Money will have a way of convincing the owners to pen or chain the dog.

Once the dog is off it's property then it is fair game as to what happens to it. It is considered to be attacking you on public property and you have a right to defend yourself. With all the dog attacks in the news these days (remember the woman in the apartment in San Francisco being killed by attack dogs and the owners being held on murder charges?) you have a perfect right to call in the authorities.

Water bottle in the face and yelling "go home" or "stay" works most of the time. I once scared a dog so badly by yelling at it, that is cowered in the road, tail between it's legs and pee'd itself. Then I felt bad, but it learned a lesson.

Last August I was caused to fall after being side attacked by a small doberman-type of dog. Spent 3 weeks off the bike with severe abrasions. Bike was OK, but scraped up a bit.

My wife likes to remind me that bad dogs are the result of bad owners and ultimately they need to be punished.