To reduce play in rotary direction in a connecting area between first and second fork stems by connecting together the first and second fork stems to permit relative movement in the axial direction while preventing relative rotation by engagement of a key with a key hole of a width narrower than the width of the key in a free state, with the key including plate springs having locking claws on the inside cylindrical surface of the second fork stem.

An elliptic slot 52 as a key hole is formed in the lower portion of a first fork stem 41 in the axial direction with a width slightly smaller than a free state width of a detent key 51 including plate springs constituting a connecting area 45. The detent key 51 including plate springs having claws 81b for engaging with cylindrical inside surface of a pipe portion 42a of a second fork stem 42 is made to engage with the key hole. Owing to the engagement, the first and second fork stems 41, 42 are connected in the connecting area 45 so that their relative movement in the axial direction is permitted while their relative rotation is prevented. Thus, play is reduced during handlebar operation in the rotary direction in the connecting area 45 between the first fork stem 41 and the second fork stem 42.