When someone wants to buy their mountain backpack, with little or no knowledge on the subject (can not think about buying a backpack on the Internet without knowing it or have it tested before), it is possible to end up leaving the shop with a super-duper 50 liter pack, capacious, with many pockets, but nothing like what they really need. Backpack capacity is measured in liters or cubic inches.
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Currently backpacks have evolved a lot, both in design, aesthetics, materials and systems for transporting load, which have undergone a major shift, to provide comfort and ease of transport as much as possible.
We should always choose a backpack that makes us comfortable, since we are going to spend many hours with it on our back, and the ideal would be not to notice it.
A very important factor in choosing a good backpack (doesn’t have to be expensive) are its frame, the size of the back and its belt; the other elements that make up the backpack, are also important, but don’t have a big influence.
The frame supports and transmits the load to the belt, therefore it must have an acceptable rigidity.
There are many materials and designs (plastics, Duralumin, carbon fiber, etc.) but the important thing is to have a good rigidity, and to allow the air to flow around the back, regardless of their material, since they have a design that allows (in theory…) air to circulate and ventilate the back better.
I sometimes use a 55 l backpack of a prestigious brand, with frame and grid and I can assure that I still get wet, so I would also advise for a conventional backpack for heavy loads (no frame), since in the end, as I say, your back will keep being wet.
The ability to adjust is an important issue, since not all brands have sizes, and most manufacture backpacks in one size, that have adjustable strapping systems which can adapt to the length of your torso; that is essential for a correct fit.
The belt and lumbar support are the main part of the backpack. In a good design it will properly the load to the waist and at the same time to the thighs, thus relieving the backbone.
The weight of the backpack rests on our shoulders, is transmitted by our torso and spine, passes to our hips and then to the feet, therefore our vertebrae and neck muscles are free of this burden. If we use correctly the belt of the backpack, the load is brought directly to the hips not overworking our shoulders and spine.
To get the most out of the belt, this should hug the sides of the waist well and not let the weight slide down. However, women having more pronounced hips, the transfer of the weight is less facilitated, so they must find a backpack adapted to their morphology and that allows them to carry the belt in a position higher than men, which in effect shortens the length of the back of the pack.
There are backpacks with women-specific markings. These have a higher belt adapted and shoulder straps that do not hinder the breasts.