I had a Great Dane come at me two days ago. I ignored him. He didn’t chase me down because he saw I was moving away from “his” turf. I was going uphill on a fully loaded bike, so it’s not like I could have outrun him. It was probably the third type of encounter in as many days.
Could it possibly be that dogs aren’t usually trying to harms us? For the ones who get too close, as squirt of water (as mentioned above) or yelling at them really loudly has always worked for me. Show them who’s top dog.