Croup and trunks (top case). Whenever you take someone on the rump, remember that you will have an extra mass placed on the rear axle. That changes the behavior of the bike, which is less stable and the braking spaces increase. In the case of the chest, it is worse because the mass is displaced behind the rear axle causing a lever that destabilizes the front of the motorcycle. Observe the load limits of the trunk and when it is charged observe the speed limits indicated by the trunk manufacturer's manual.