  The limiting rotational frequency of neutron stars may be determined by the
strength of their crusts. As a star spins up from accretion, centrifugal forces
will cause the crust to fail. If the crust breaks unevenly, a rotating mass
quadrupole moment will radiate gravitational waves (GW). This radiation can
prevent further spin up and may be a promising source for continuous GW
searches. We calculate that for a breaking strain (strength) of neutron star
crust that is consistent with molecular dynamics simulations, the crust may
fail at rotational frequencies in agreement with observations.
