The invention relates to a device including a carrier, two flyweights, and two rolling elements, one (10) of which has a stabilized bearing surface (12) comprising two circumferential radial bosses (17) for rolling contact with one of the flyweights or with the carrier, each of said bosses (17) comprising a maximum diameter area (DM) having the same diameter, both of said bosses (17) defining, between the maximum diameter areas, an annular area (18) of the bearing surface in which the diameters are smaller than the maximum diameter.