Replaceable head tube device of bicycle

The utility model relates to a replaceable head tube device of a bicycle, which is provided with a frame. A head lower tube penetrates through the front end part of the frame; a head upper tube extending upwards is combined with the top of the head lower tube in a dismountable mode; a top cover is combined with the top surface of the front end part of the frame; and the top of the front end of thetop cover is provided with a penetrating hole sleeved at the periphery of the top end of the head upper tube. When the replaceable head tube device is used, a straight rod of a front fork is insertedinto the head upper tube and the head lower tube, the top end of the straight rod of the front fork is combined with a stand pipe extending forwards, and the front end of the stand pipe is combined with a handle. Since the head upper tube is in a replaceable design, head upper tubes with different heights can be replaced according to different competition occasions, and different riding requirements of users can be satisf