The responses so far get right to the heart of the problem. Many owners of agressive dogs are delighted to see their pet attack a cyclist. I tried pepper spray many years ago. It will take a dog down quickly if hit in the face. However, it also brings the owner of the dog off the couch on his front porch. Even worse. Also, pepper spary is useless in a strong wind.

Therefore, I was hoping an electronic device has been developed that will actually turn an agressive dog around. Probably not realistic, just hoping.

Also, I am not that worried about a dog bitting me. I am worried about a dog taking my bike down. I followed a good friend last year that had his front wheel hit by an agressive dog. It took my friend down at 20 MPH on the asphalt. Not a pretty site. The dog ran away unharmed and I do not want the dog hurt, but I want some way to turn such a dog around before he takes MY front wheel out.