Most of the time, dog chases occur in parks where they are supposed to be leashed. I called the city once on a dog and owner I had encountered three times. But I realize I can't call them all the time since these occurrences are random and impossible to enforce.
I ride slowly enough so I won't run over the dogs. If I ride too fast, it may trigger their chase response. So I ride slowly enough for them to keep up with me and fast enough so that I can lead them pretty far and make the owner panic.
I did carry pepper spray with me for a while. If calling out at the dog " Bad dog! Go home!" works I'm wondering if I should carry a rolled up newspaper.