  The period versus mass diagrams (i.e., rotational sequences) of open clusters
provide crucial constraints for angular momentum evolution studies. However,
their memberships are often heavily contaminated by field stars, which could
potentially bias the interpretations. In this paper, we use data from Gaia DR2
to re-assess the memberships of seven open clusters with rotational data, and
present an updated view of stellar rotation as a function of mass and age. We
use the Gaia astrometry to identify the cluster members in phase-space, and the
photometry to derive revised ages and place the stars on a consistent mass
scale. Applying our membership analysis to the rotational sequences reveals
that: 1) the contamination in clusters observed from the ground can reach up to
$\sim 35\%$; 2) the overall fraction of rotational outliers decreases
substantially when the field contaminants are removed, but some outliers still
persist; 3) there is a sharp upper edge in the rotation periods at young ages;
4) stars in the 1.0-0.6 Msun range inhabit a global maximum in terms of
rotation periods, potentially providing an optimal window for habitable
planets. Additionally, we see clear evidence for a strongly mass-dependent
spin-down process. In the regime where rapid rotators are leaving the saturated
domain, the rotational distributions broaden (in contradiction with popular
models), which we interpret as evidence that the torque must be lower for rapid
rotators than for intermediate ones. The cleaned rotational sequences from
ground-based observations can be as constraining as those obtained from space.
