US Patent 7931283 Frame assembly for in-line skate

An in-line skate frame assembly has a rigid frame and an elongate grinding insert releasably engaged with the frame. The frame and insert are secured together to the sole of a shoe or boot by frame bolts extending through upper portions of the frame and insert. The frame has spaced side walls with downwardly facing recessed regions in which the insert is mounted. The insert extends along a major portion of the length of the frame and has a downwardly facing, centrally located grinding surface which terminates short of the opposite ends of the insert. Different inserts with grinding surfaces of different shapes and lengths are releasably secured to the frame for performing alternative grinding maneuvers.