We use the notion of generalized connection over a bundle map in order to
present an alternative approach to sub-Riemannian geometry. Known concepts,
such as normal and abnormal extremals, will be studied in terms of this new
formalism. In particular, some necessary and sufficient conditions for the
existence of abnormal extremals will be derived. We also treat the problem of
characterizing those curves that verify both the nonholonomic equations and the
so-called vakonomic equations for a `free' particle submitted to some
kinematical constraints.Comment: accepted for publication in J. Geom. Phy