For those of you been looking for a real disc brake setup and wondering when BBR was going to have it done, its finally up on there site, and looks pretty sweet. They have adapters so it will fit stock style frames as well.
BBR CRF/XR50 Rear Disc Brake Kit $499.95 (Available now in limited quantites)
Description: Over 1 year in development, the BBR Rear Disc Brake Kit for the CRF/XR50 is finally here! We've destroyed hundreds of prototypes and trash canned every mountain bike brake made. We wouldn't sell it until it could hold up to the abuse the BBR race team dishes out. This is a real motorcycle brake developed from the ground up for the CRF/XR50. Super strong with unbelievable pedal "feel", this is the ultimate fix for you broken rear hub blues.
Includes billet aluminum hub, full motorcycle style brake system, and billet aluminum brake pedal. Fits BBR Perimeter Frame Kit, or most other frames with our adapter kit.
Features: • 1 piece billet aluminum hub in black, silver, or red with 3 giant bearings.
• Thick motorcycle brake rotor.
• Full hydraulic motorcycle mini brake caliper and master cylinder (NOT mountain bike brakes).
• Billet brake pedal with (3 position) replaceable tip.
• Fits standard CRF/XR50 sprockets.
• Adapter kit adapts the rear disc brake to the OEM Honda frame, the BBR Super Pro aluminum frame, and most aftermarket frames and swingarms.
• This hub requires our 10" Heavy Duty Spoke Set. or our 12" Heavy Duty Spoke Set
• Check out our 10" and 12" anodized aluminum rims
• Check out our selection of Tires and Tubes
• Don't forget the Rim Lock
Applications: 550-HXR-5011 Rear disc brake kit for BBR Perimeter 50 (Black hub)
550-HXR-5031 Rear disc brake kit for BBR Perimeter 50 (Silver hub)
550-HXR-5041 Rear disc brake kit for BBR Perimeter 50 (Red hub)
550-HXR-5050 Rear disc brake adapter kit ($49.95)
680-BBR-1040 Lace and true wheel (CRF/XR50) ($50)

BBR CRF/XR50 Rear Disc Brake Kit $499.95 (Available now in limited quantites)
Description: Over 1 year in development, the BBR Rear Disc Brake Kit for the CRF/XR50 is finally here! We've destroyed hundreds of prototypes and trash canned every mountain bike brake made. We wouldn't sell it until it could hold up to the abuse the BBR race team dishes out. This is a real motorcycle brake developed from the ground up for the CRF/XR50. Super strong with unbelievable pedal "feel", this is the ultimate fix for you broken rear hub blues.
Includes billet aluminum hub, full motorcycle style brake system, and billet aluminum brake pedal. Fits BBR Perimeter Frame Kit, or most other frames with our adapter kit.
Features: • 1 piece billet aluminum hub in black, silver, or red with 3 giant bearings.
• Thick motorcycle brake rotor.
• Full hydraulic motorcycle mini brake caliper and master cylinder (NOT mountain bike brakes).
• Billet brake pedal with (3 position) replaceable tip.
• Fits standard CRF/XR50 sprockets.
• Adapter kit adapts the rear disc brake to the OEM Honda frame, the BBR Super Pro aluminum frame, and most aftermarket frames and swingarms.
• This hub requires our 10" Heavy Duty Spoke Set. or our 12" Heavy Duty Spoke Set
• Check out our 10" and 12" anodized aluminum rims
• Check out our selection of Tires and Tubes
• Don't forget the Rim Lock
Applications: 550-HXR-5011 Rear disc brake kit for BBR Perimeter 50 (Black hub)
550-HXR-5031 Rear disc brake kit for BBR Perimeter 50 (Silver hub)
550-HXR-5041 Rear disc brake kit for BBR Perimeter 50 (Red hub)
550-HXR-5050 Rear disc brake adapter kit ($49.95)
680-BBR-1040 Lace and true wheel (CRF/XR50) ($50)