Steering post tube

The utility model relates to a steering post tube which is benefit for the choosing of standard bearings and the adoption of the clock spring with a big diameter. Wherein, a steering mandrel is supported and fixed by a steering bearing; the head of the steering post tube is a variable shape namely the diameter of the two ends are big and the diameter of the tube body is small; the steering bearing is fixed and arranged by means of an auxiliary bush, and therefore the standard springs with a small size can be chosen and the tube ends with a bigger size can be obtained, so a combination switch can be arranged conveniently so as to meet the needs for using the clock springs with a bigger diameter.