  We study longitudinal magnetotransport in disorder-free cylindrical Weyl
semimetal nanowires. Our theory includes a magnetic flux $\Phi$ piercing the
nanowire and captures the finite curvature of the Fermi arc in the surface
Brillouin zone through a boundary angle $\alpha$. Electron backscattering by
acoustic phonons via the deformation potential causes a finite resistivity
which we evaluate by means of the semiclassical Boltzmann approach. We find
that low-energy transport is dominated by surface states, where transport
observables are highly sensitive to the angle $\alpha$ and to Aharonov-Bohm
phases due to $\Phi$. A generic subband dispersion relation allows for either
one or two pairs of Fermi points. In the latter case, intra-node backscattering
is possible and implies a parametrically larger resistivity than for a single
Fermi point pair. As a consequence, large and abrupt resistivity changes take
place across the transition points separating parameter regions with a
different number of Fermi point pairs in a given subband.
