Head tube assembly

A head tube assembly adapted to be mounted between a head tube and a front fork of a vehicle, the front fork extending through the head tube and said head tube assembly and rotatable relative to the head tube about an axis, said head tube assembly comprising:

• a cup member that is adapted to be mounted fixedly to the head tube;
• an insertion member that is adapted to be connected co-rotatably to the front fork, and that includes an insertion body having
• an inner abutment surface that is adapted to abut against said front fork, and
• an outer connecting surface that is connected to said inner abutment surface;
• and
• a damping unit disposed on the axis between said cup member and said insertion member, connected to said insertion member, and including
• an outer seat that is fixedly connected to said cup member,
• an inner seat that is connected co-rotatably to said insertion member and that has an inner connecting surface that abuts against said outer connecting surface of said insertion body, and
• a bushing that is mounted on the axis between said outer seat and said inner seat, said outer seat and said inner seat being in frictional contact with said bushing and rotatable relative to said bushing about the axis;
• wherein each of said inner seat and said insertion body has an eccentric structure such that said insertion member drives rotation of said inner seat as being rotated.