A mono-beam trailer and support assembly for transporting a motorcycle in an upright position without the use of straps or ropes. A single elongate main beam, upon which the motorcycle is carried, pivots vertically and laterally relative to the towing vehicle but cannot rotate axially. A "T" bar assembly pivotally carried by the main beam releasably communicates with replacement foot peg pins installed on the motorcycle foot peg fastening brackets releasably securing the motorcycle to the main beam and preventing undesirable movement thereof. A pivotal swing arm at a rearward end portion of the main beam has a wheel truck thereon for towable movement of the trailer. The swing arm may be pivoted vertically and laterally on to mutually perpendicular axles to a position adjacent the elongate main beam to ease the loading and unloading of the motorcycle.