I have been have seen shouting "go home" loud work. Also, riding faster is good advice, the dogs natural instinct is to come up from behind, which is where you want it to be, behind you, not at your side or at your front wheel. Often, once the dog has run to the end of his "territory" he will stop. Try squirting your water bottle at it if it gets too close, I've seen this work too. I have heard of a commercial dog repellent call "Halt" though I haven't tried it.