Abstract: A hub adapter used to modify a bicycle wheel hub to provide for the mounting of a disc brake rotor and/or for the repositioning of the wheel spoke mount flange to accommodate the additional components of a disc brake system. The hub adapter may be fixed to the host non-disc wheel hub by fastening bolts passing through the original spoke mounting holes or by other fastening means. The hub adapter may provide standard mounting holes for a disc brake rotor to be fixed to the hub adapter with fastening bolts. The hub adapter provides alternate spoke mounting holes on an alternate spoke flange, positioned in such a way so as to provide adequate clearance for disc brake components such as the disc brake caliper assembly, or in such a way as to change the length of the spokes and to modify the wheel stiffness. The hub adapter effectively becomes integral to the host wheel hub and critical to the primary function of the wheel hub, that is transferring load from the frame to the wheel.