Patent ID: 8760799

Claim:
A rotor hub for use in a motor of a disk drive, comprising: a shaft connecting portion arranged to be connected to a shaft serving as a central axis; a disk loading portion centered about the central axis, arranged radially outside the shaft connecting portion so as to surround the central axis, and arranged to support a disk-shaped storage medium loaded thereon; a hollow, approximately cylindrical yoke arranged below the disk loading portion, centered about the central axis, and supporting a field magnet at one of an inner side surface thereof and an outer side surface thereof; and a flexible portion connecting the disk loading portion to the yoke and arranged to absorb a force applied thereto from the yoke; wherein the flexible portion includes a recess on its radially outer side surface, the recess being concave radially inward and having an annular shape centered about the central axis with all portions of the recess being substantially empty; and the recess is arranged directly above the yoke and axially between the disk loading portion and the yoke.