It is a very rare occurance to encounter an uncontrolled dog in the parts of Australia where I've cycled, or in many parts of Canada ... although I did encounter several in Alberta.

In most instances, what worked was to pretend to throw something. Pretend you've got a ball or stick in your hand and throw hard. The dog goes dashing off after the imaginary ball, and you cycle away.

Stopping, getting off the bicycle, and standing with the bicycle between you and the dog can also work. I've done that a couple times. Apparently, when we're on our bicycles, the dog isn't sure what we are and will chase us. But when we stop and get off the bicycle, the dog realises that we're human, like their master. A loud "Go Home", and off they go.

It also helps to know your breed. For example, border collies will herd you, and it can help to let them know you're human and not herdable animal. So talk to them.

What can be a bit unnerving is when you've got at least two large dogs coming after you. That has happened to me a couple times.