Abby was a very frequent (and painful) nipper especially if I was hurrying. Nothing could dissuade her. After realising that she was not understanding the 'No' command, I decided to try rewards. I had already taught her to 'Sit' so each time she would start chasing my legs I would turn and bellow a very loud 'Sit' which would take her by surprise and she would immediately obey with a very startled look on her face. I would then reward her for sitting. After doing this for a while the nipping completely ceased.
Oh,Happy Days.