[alf]

According to my Pakr Ranger friend they were trained that a knife in the lungs or a finger up the anus of a pit bull will un-clamp its jaw. I wonder what you do with the dog after it unclamps with your finger up its ass, leave it there so it does not bite you again? Knife better i think.

Oh for your bike problem...consider either riding faster or dismounting with bike between you and dog while you reach for your folder or prepare to point finger.