  We propose a complete theoretical description of the tennis racket effect,
which occurs in the free rotation of a three-dimensional rigid body. This
effect is characterized by a flip ($\pi$- rotation) of the head of the racket
when a full ($2\pi$) rotation around the unstable inertia axis is considered.
We describe the asymptotics of the phenomenon and conclude about the robustness
of this effect with respect to the values of the moments of inertia and the
initial conditions of the dynamics. This shows the generality of this geometric
property which can be found in a variety of rigid bodies. A simple analytical
formula is derived to estimate the twisting effect in the general case.
Different examples are discussed.
