ROTOR ADAPTOR - [ADAPTOR ONLY does not include Disc] allows installation of any standard rotor to a Hub which is threaded for a freewheel or band brake.  We use this piece  to turn our REAR Stingray wheels into a FRONT Wheel w/Disc  Brake.

SEE PHOTO and  CLICK ON LINK:  to see how we use the adaptor.

 http://www.pedalchopper.com/wide-ride-forks-fat-boy-style-forks/