Adjustable vehicle-carrying frame

An adjustable frame for carrying vehicles between elongate upright sides includes, on each side, a forward end and a rearward end, each end including an upper and lower rail section joined by elongate brace members, where the respective ends are separated from one another and a length-adjusting insert is carried between such ends to selectively permit adjustment of the position of the forward end relative to the rearward end while maintaining the ends in end-to-end alignment. On each side of the frame, preferably at least one of the upper rail sections has an end portion defining an open-ended hollow tube extending lengthwise of that side within which an elongate arm of the length-adjusting insert is slidably moveable so that structures on the outside surfaces of the rail sections will not interfere with length adjustment. Preferably, on each side, the upper and lower rail sections of the respective ends together define longitudinally aligned upper and lower pairs of open-ended tubes in which are slidably received an upper and lower pair of arms of the length-adjusting insert, thereby permitting the insert to remain permanently in position on each side regardless of the length selected. Preferably, also, the forward and rearward ends of the frame are lockable to the arms of the insert while keeping the insert centered longitudinally with respect to each side.