Evolution of the half-mass radius (dashed colour lines) of each model calculated from stars that are bound to the cluster, i.e. up to the tidal radius from Eq. (A.1), which is plotted by a solid line. An artificial half-mass radius, which should represent the cluster evolution after gas expulsion, is plotted by the lighter dashed line for each model. The mean value ⟨τ_v⟩ of each model is plotted by a dashed vertical line for reference.