  In this paper a special group of bijective maps of a normed plane, called the
group of general rotations, is introduced; it contains the isometry group as a
subgroup. The concept of general rotations leads to the notion of flexible
motions of the plane, and to the concept of Minkowskian roulettes. As a nice
consequence of this new approach to motions the validity of a strong analogue
to the Euler-Savary equations for Minkowskian roulettes is proved.
