  We have surveyed the in-plane transport properties of the graphene twist
bilayer using (i) a low-energy effective Hamiltonian for the underlying
electronic structure, (ii) an isotropic elastic phonon model, and (iii) the
linear Boltzmann equation for elastic electron-phonon scattering. We find that
transport in the twist bilayer is profoundly sensitive to the rotation angle of
the constituent layers. Similar to the electronic structure of the twist
bilayer the transport is qualitatively different in three distinct angle
regimes. At large angles ($\theta > \,\approx\!\!10^\circ$) and at temperatures
below an interlayer Bloch-Gr\"uneisen temperature of $\approx 10$~K the
conductivity is independent of the twist angle i.e. the layers are fully
decoupled. Above this temperature the layers, even though decoupled in the
ground state, are re-coupled by electron-phonon scattering and the transport is
different both from single layer graphene as well as the Bernal bilayer. In the
small angle regime $\theta <\,\approx\!\!2^\circ$ the conductivity drops by two
orders of magnitude and develops a rich energy dependence, reflecting the
complexity of the underlying topological changes (Lifshitz transitions) of the
Fermi surface. At intermediate angles the conductivity decreases continuously
as the twist angle is reduced, while the energy dependence of the conductivity
presents two sharp transitions, that occur at specific angle dependent
energies, and that may be related to (i) the well studied van Hove singularity
of the twist bilayer and (ii) a Lifshitz transition that occurs when trigonally
placed electron pockets decorate the strongly warped Dirac cone. We examine the
role of a layer perpendicular electric field finding that it affects the
conductivity strongly at low temperatures whereas this effect is washed out by
Fermi smearing at room temperatures.
