I too run front and rear Contour HD cameras, I have them both very rigidly mounted to the bike frame, so as to limit the amount of vibration in my videos, plus lower pressure tires are helpful too. As for frame or helmet mounted, I chose frame mounted since I'm constantly working urban traffic and my head is basically on a swivel, which gave my early videos too much of a "Blair Witch effect", and my main goal is capturing vehicle descriptions and license plate numbers.