Gotta add my 2 cents...
I've had an unfortunately large amount of experience dealing with dogs both as a runner and as a cyclist.
As a cyclist I used to just kick the dog, and that worked, fine (the dog never expects you to fight back in any way!) as a deterrent to further agression. And I never fell off my bike doing it, or such. But I always disliked actually injuring the beast--as has been pointed out, it's the owner's fault, not the dog's, that the dog is out in the street chasing you.
Anyhow, after shutting a German Shepherd's mouth on his tongue, with my heel, one time, with a kick from aboard my bicycle, I decided that the chemical spray was more humane. Began carrying that.
As to wind, the chem. spray comes out in a solid stream which is good for 10-12 feet on a still day, and with a brand-new can. After several years of carry, that range gets cut in half, at which point I retire the can and buy a new one. The dog is always close enough to me on the bicycle that wind would not be a factor--you just hose down his whole face anyhow. I've had errant small amounts of spray hit another rider, who reported that it was very hot and uncomfortable in his eye/mouth, but bearable. And the effects are gone after several hours, even with no treatment.
I generally hold the spray can with my fingers, and press the button with my thumb. The cans are set up so you can tell by feel which way the spray is pointed.
As to effectiveness: I have stopped a Doberman pinscher in full-out attack mode, coming at me while running on the street. (Scary sight!) Waited until he was abt. 8 feet away, hosed down his face, and he suddenly remembered he had an appointment elsewhere.
I have also held off 3 black Labrador retrievers, and a standard poodle, all at the same time, while on my bicycle. Hosed down each of the Labs in turn--One of them couldn't believe how bad it was, and came back to try again. The second time, he believed. Never got to squirt at the poodle--when the poodle saw how the Labs were faring, he hung back--smart dog! All the while the dogs' owner was standing in the road yelling at me.
Bottom line: I have experience with this. The dog spray DOES WORK, and IMHO, it is far more humane than hitting the dog. It doesn't do permanent damage to dogs or humans.
