Timescale associated with the stellar rotational angular momentum as a function of age for a twin system with low eccentricity (e = 0.1) and high initial rotation rate (Ω_rot = 0.3Ω_crit), corresponding to the case shown in Fig. 3. The plotted modes are retrograde, with orbital harmonics k distinguished by colour. A long-term resonance locking with the k = −2 mode is visible as a plateau, while the peaks correspond to resonance crossings.