  The internal rotation of post-main sequence stars is investigated, in
response to the convective pumping of angular momentum toward the stellar core,
combined with a tight magnetic coupling between core and envelope. The spin
evolution is calculated using model stars of initial mass 1, 1.5 and
$5\,M_\odot$, taking into account mass loss on the giant branches. We also
include the deposition of orbital angular momentum from a sub-stellar
companion, as influenced by tidal drag along with the excitation of orbital
eccentricity by a fluctuating gravitational quadrupole moment. A range of
angular velocity profiles $\Omega(r)$ is considered in the envelope, extending
from solid rotation to constant specific angular momentum. We focus on the back
reaction of the Coriolis force, and the threshold for dynamo action in the
inner envelope. Quantitative agreement with measurements of core rotation in
subgiants and post-He core flash stars by Kepler is obtained with a two-layer
angular velocity profile: uniform specific angular momentum where the Coriolis
parameter ${\rm Co} \equiv \Omega \tau_{\rm con} \lesssim 1$ (here $\tau_{\rm
con}$ is the convective time); and $\Omega(r) \propto r^{-1}$ where ${\rm Co}
\gtrsim 1$. The inner profile is interpreted in terms of a balance between the
Coriolis force and angular pressure gradients driven by radially extended
convective plumes. Inward angular momentum pumping reduces the surface rotation
of subgiants, and the need for a rejuvenated magnetic wind torque. The
co-evolution of internal magnetic fields and rotation is considered in Kissin &
Thompson, along with the breaking of the rotational coupling between core and
envelope due to heavy mass loss.
