What does the fortune teller mean by not changing the trajectory?

What several experts upstairs said is most likely 5 points, and every point below is possible. The more likely it is to be in the front, you can refer to the analysis. Basically, swing the rear wheel left and right by hand to see where it is shaking and swinging, and then you will know what is wrong.

1 point, most likely the rear wheel spokes (steel wire) are loose. The big (foot) bracket of motorcycle can be erected and the rear wheel can be suspended. Swing the rear wheel left and right by hand to see if the spokes (steel wire) can swing. If it can swing, it means it is loose. You need to find a master who can "correct or adjust" the spokes of the wheel rim to repair them. Generally, few motorcycle maintenance masters can do this.

The second possibility is the deformation phenomenon caused by irregular inflation of the rear wheel tire. Identification method: Turn the rear wheel to see if the track of tire rotation is a basic circle (or circumference). If it is deformed, it will jump and move irregularly. Generally speaking, this deformation is the irregular combination of the "tire lip" part of the tire and the tire rim. The solution is to add some grease (not liquid engine oil) to the tire lip and inflate it again. In the process of inflation, some skills are needed to correct it. If it is too expensive or too troublesome, just change a new tire.

The third point is that the buffer sleeve of the middle shaft of the frame is worn and damaged. Most of the middle shaft I said is behind the motorcycle engine and near the middle joint of the exhaust pipe (chimney and muffler), and there is a buffer sleeve (buffer sleeve) inside. Please replace the old one with the new one.

The fourth point is the rim deformation of the rear wheel tire. If the deformation is serious, it needs to be replaced with a new one. In short, the whole rear wheel can be corrected by "straightening" the spoke line (steel belt line) so that it approaches a circle when rotating.

The fifth point is that the rear wheel bearing is damaged or worn "loose". It should be noted that the reason for the shock absorber mentioned by the master upstairs is probably very small.

Whether a tire is loaded depends on whether the spokes are "straightened", which determines whether the whole tire is round. This is the most important thing, and the tire, steel ring, shock absorber and bearing are all secondary.