Upper panel: Average rotational velocity along the HR diagram (color code). Lower panel: Evolution of the average rotational velocity as a function of the T_eff. The color code is the same as in Figure 6. Dashed lines represent the main sequence evolution, solid lines the advanced phases. The velocity drops during the main-sequence evolution. This is followed by the hook at the end of the main sequence, when the velocity quickly rises due to post main sequence contraction, and by a subsequent drop. In the late phases of the evolution log(T_eff/K)≳5.05, the velocity rises again due to winds peeling-off the outer layers of the star and exposing the rotating core.