any other vintage motorcycle, scooter or microcar (like Isetta or Messerschmitt). Having just one wheel, these trailers are attached to the towing vehicle by a hitch that has only two degrees of freedom — pitch and yaw. Hitching a trailer to a motorcycle In order to tow a trailer behind a motorcycle, one of the following coupling combinations or mechanisms is needed: a ball and socket, swivel adapter, or pivot ball hitch and coupler. Ball and socket Most trailers are towed by joining a ball and a coupler (socket). The coupler is attached to the trailer, and the ball hitch is attached to the tow vehicle. The coupler slides over the ball hitch. Then, pressure is applied to a clamp, usually with a toggle or lever, which secures the ball in the coupler. When properly attached, the coupler will have limited movement, swiveling mainly right and left as well as tilting slightly. Swivel adapter (swivel coupler - swivel hitch) The swivel adapter, more commonly referred to as a swivel coupler or swivel hitch, functions by connecting one end to the trailer tongue and the other end directly to the hitch on the tow vehicle or to a coupler. This mechanism is engineered to rotate on the vertical axis so as to eliminate the possibility of coupler binding. As a result, the motorcyclist is able to lean into a turn as far as necessary at high speeds while keeping the trailer upright. Anti-binding motorcycle trailer hitch assembly (pivot ball hitch) The pivot ball hitch is an anti-binding motorcycle trailer hitch assembly composed of a base and a trailer ball. The base is secured to a standard ball mount on the motorcycle. The trailer is attached to a socket coupler. A space between the ball shank and the assembly mount allow the ball to move left and right in a vertical plane. Thus, the ball remains in a generally upright position when the motorcycle leans left or right into a turn because the base of the pivot ball hitch is able to move in the opposite direction of the motorcycle without causing the coupler to bind. Coupler binding Making a turn on a single-track vehicle such as a two-wheeled motorcycle requires the driver to lean the bike. The amount of the lean is dependent upon the speed. Faster speeds require more leaning than slower speeds do. When making a turn with a