A disk drive includes a base, and a spindle motor coupled to the base. The
spindle motor includes a hub defining an axis of rotation. The disk drive
further includes a disk disposed about the hub and including a disk inner
diameter biased against the hub at a contact location of the hub. The
disk drive further includes a balancing element including a cylindrical
portion disposed about the hub. The balancing element further includes a
first cavity defining a first cavity centroid disposed on a same side of
the axis of rotation as the contact location, and a second cavity
defining a second cavity centroid disposed on a side of the axis of
rotation opposite the first cavity centroid. The second cavity centroid
is spaced apart from the first cavity centroid in a direction along the
axis of rotation.