PURPOSE: To obtain a two-wheel drive motorcycle frame made lighter in weight by welding a bearing housing for an input shaft of a synchronous joint avialable for front wheel drive, to the front end of a main tube at the right of symmetrical main tubes of the frame, and attaching it to the thick and stout main tube.

CONSTITUTION: A front part of a main tube 15 at the left out of two symmetrical tubes 15 of a frame 12 is bent inward and a front end is welded to the upper part of a head pipe 13, while the main tube 15 at the right is extended toward a lower side of the head pipe 13, welding it to a bearing housing 16, and this bearing housing 16 and the head pipe 13 are connected by a sub pipe 17 by means of welding, then a bearing for an input shaft 18 of a synchronous joint 5 for front wheel drive is attached to the bearing housing 16.