I'm a dog lover too ... was a groomer and trainer for 17 years. We get more than our share of loose dogs around here but most of them are no problem. Dogs who aren't familiar with bicycles aren't likely to recognize right off the bat that there are humans attached so we look like fair game to them. Most of the time these are friendly family pets and a gentle eye contact with a softly-spoken "well, hello there, fella" and you can watch their eyes soften as they realize there's a person up there and sit back. You can almost see the "oh bummer, THAT'S no fun!" thought-balloon over their heads. If that doesn't work, most dogs have at least learned the meaning of the word "no."

On the other hand, if a dog challenges me I'm not strong enough yet to try to outride him so I'll challenge him right back with my best top-of-the-lungs bring it on pal and I'll beat you to death with my bike voice accompanied by two more steps and I'll have you by the throat body language. The trick to the whole thing is to MEAN IT. If you don't firmly believe, beyond a shadow of a shade of a doubt, that you can kill that dog, don't start it. Thing is, I do ... at least, in that moment.

That behavior on my part serves two purposes: First, I haven't met a dog yet that wasn't impressed enough to slow down long enough for me to get into a defensive (behind the bike) position, and second ... my voice is loud enough to bring the entire neighborhood out to see what's going on. Good fun at 5:30 in the morning.