Abstract: Recording medium disk-hub combination wherein the hub has a central hole whose periphery is bounded at least partly by three flexure members which circumscribe a cylinder corresponding to a disk drive spindle. The three flexure members are arranged in a triangular configuration, and the parts of such flexure members that circumscribe the cylinder are coplanar, forming a flexure member plane of contact. The axial center line of the recording medium disk is spaced from the flexure member plane of contact by no more than three times the thickness of the disk itself. The combination is preferably designed with the ratio of the coefficient of thermal expansion of the hub to that of the recording medium disk being between 0.7 and 1.4. Hub is made magnetic, e.g., by attaching a magnetizable disk. The combination is especially useful for removable recording disks intended to cooperate with disk drives having circular motor spindles and magnetic hold down.