Urban travel is not very particular, the key lies in whether it is comfortable to carry, and the choice of backpack material: canvas is wearable, but it is rarely used because it is easy to get wet, difficult to dry when wet, and heavy in weight. Nylon cloth has light weight, no moisture absorption and mildew, fast drying and good strength; The disadvantage is that it is not wear-resistant and afraid of fire. Cordura cloth is also a kind of synthetic nylon cloth, but its wear resistance and strength are better than that of nylon, and it also has no moisture absorption, no mildew, no adhesion to snowflakes and quick drying, but it is slightly heavier than nylon. Selection of capacity: capacity is an important factor in purchasing backpacks: insufficient capacity, cumbersome hanging items outside, and easy to lose; If the capacity is too large, the backpack will not be strong when packing, and the equipment in the bag will affect the balance when moving. Therefore, the selection of backpack capacity must first establish a personal equipment list. Backpack system: Backpack system can't completely solve the weight problem of backpack. Its main function is to distribute the weight to all parts of the body reasonably and avoid concentrating the weight on the shoulders. Although the high center of gravity design is not suitable for occasions requiring high balance, it will be more comfortable to carry on flat roads. This kind of backpack is also easy to install and carry, and the weight can be borne by shoulders and hips. Because the backpack outside the frame is carried by a shelf, the back is well ventilated. Choosing a backpack that suits you can not only make your trip more enjoyable, but also reduce more unnecessary troubles during the trip. If you go hiking like a donkey friend, you should bring all your equipment. You can't just consider thin fabrics. You have to consider factors such as waterproof, firmness and whether your back is comfortable for a long time. If you take care of all the functional packages, it will definitely not be much lighter. If you just bring some portable water cups and cameras, you can choose fabrics similar to skin trench coats that many brands have. I recommend one of Decathlon, which can be rolled into a ball when not in use and is easy to carry. Take out a thin layer when you need it, and there is a small pocket. Everything is light and does not pinch your shoulders when you carry it.