Before purchasing a backpack, you should loosen all the adjustment belts and add weight, because if you don't have weight, you can't know the feeling of the backpack and the adjustment range.
After carrying the backpack, check whether the curvature of the inner aluminum strip and the curve of the back are consistent. If it is not, check whether the aluminum strip is bendable. If it is bendable, the aluminum strip will naturally bend into a curve matching the back after a period of use. Is the backpack and back contact part comfortable and breathable?
The shoulder strap and backpack connection must be 5-8 cm below the shoulder, and the gap between the shoulder strap and the backpack should be small. The chest strap adjusts the width of the shoulder strap at the chest and allows the shoulder strap to be more comfortable on the shoulder and prevents the backpack from shaking.
After adjusting the backpack to the most suitable position, should you check the line of sight of the head? Can you look up and not touch the top of the backpack? Can I still look up to the sky when I put on my helmet?
The adjustment range of the shoulder strap must match the length of the back to bring the center of gravity to the desired position; the hip belt must be able to be tied to the tibia. When you carry your backpack, you should be able to see your hips and legs from the back. Women who are more petite should pay special attention to this. You can only see the backpack and calf from the back when you are carrying your backpack. This is very wrong and dangerous.