New 11" Carbon Rotor Disc Brake Kit from Hawaya Racing Products Rear braking on the Nitro Harleys has always been weak. The faster these bikes go and the heavier they get, the worse the problem becomes. We have a solution for this problem. We borrowed the carbon disc and caliper from the car industry, then designed and machined the necessary components to adapt them to the Nitro Harleys for unmatched stopping power.