  We investigate the temporal evolution of the electronic states at the bismuth
(111) surface by means of time and angle resolved photoelectron spectroscopy.
The binding energy of bulk-like bands oscillates with the frequency of the
$A_{1g}$ phonon mode whereas surface states are insensitive to the coherent
displacement of the lattice. A strong dependence of the oscillation amplitude
on the electronic wavevector is correctly reproduced by \textit{ab initio}
calculations of electron-phonon coupling. Besides these oscillations, all the
electronic states also display a photoinduced shift towards higher binding
energy whose dynamics follows the evolution of the electronic temperature.
