Abstract: The invention relates to motorcycles of the kind comprising a rear wheel axis carried by at least one suspension arm mounted for oscillations about a suspension travel axis, a resilient suspension member acting between a frame and the suspension arm, and a loop transmission connecting a driving pinion with a driven pinion solid with the rear axle. The technical problem is to provide such a motorcycle with greater suspension stability by under acceleration. In accordance with the invention, in the flat road running condition, the suspension travel axis is disposed in the same plane as the axes of the driving and driven pinions, in front of the driving pinion, so that transmission loop tension tends to reduce suspension excursions. The invention is applicable to chain drive and other loop drives.