We introduce the peak normal form of elements of the Baumslag-Solitar groups
BS(p,q). This normal form is very close to the length-lexicographical normal
form, but more symmetric. Both normal forms are geodesic. This means the normal
form of an element $u^{-1}v$ yields the shortest path between $u$ and $v$ in
the Cayley graph. For horocyclic elements the peak normal form and the
length-lexicographical normal form coincide.