You want these http://motorbicycling.com/f23/beefed...0-a-18927.html
I got them before they were being offered heavy duty borderline OK for a bicycle but destined to fail. I got them done up by SportsCarPat and now I feel quite comfortable knowing they will hold up to the stress of aa motorbike. Do Yourself a favor spend the extra money up front if You dont you will wish you did later. VeniceMotorBikes sells them as well as SportsCarPat both members here.