The "back" bag, as its name implies, needs our backs to support the weight of the backpack well. In that case, the one-shoulder backpack must be completely wrong.
In the actual process of carrying schoolbags, people often think that as long as they wear straps on their shoulders and don't take a crooked road, there will be no problem. In fact, we only consider the influence of the way the shoulder is stressed on the body, but do not consider the stress caused by the length of the backpack strap on the shoulder and back.
When carrying a backpack, if the strap of the backpack is too long, the main body of the backpack may be lower than the waist or even the buttocks, resulting in that the backpack that should be in contact with the back is only stressed at the shoulders, waist and buttocks. If the backpack is heavy, it will cause excessive local pressure and cause discomfort.
This problem can be solved by adjusting the length of the backpack strap: after carrying the backpack, pull down the end of the strap with both hands and the strap will automatically tighten. You can feel that with the tightening of the straps, the schoolbag on the back is getting lighter and lighter, which is the result of the full contact between the backpack and the back and the gradual dispersion of pressure. If you feel that the strap is too tight when you take off your backpack, just gently lift up the strap buckle of your backpack, and the strap will automatically loosen, so you can easily take off your backpack.