Hiking boots are known for their durability and longer lifespan compared to other footwear, considering that the proper care and maintenance for the boots are applied. Contributing to that fact are the parts of the boots that are known to be the core of the footwear’s strength: the midsole and outsole.
The midsole is found between the boot’s traction-giving outsole and upper body. The purpose of this part is to provide cushioning, besides protecting the feet from most sources of shock and also determines stiffness. Usually, the midsole is made from EVA (ethylene vinyl acetate) or polyurethane. The difference in the two is that EVA is cushier, lighter and less expensive, which is suitable for trail shoes and light hiking boots, and it is applied in varying densities, more on where firmer support is required. Polyurethane, on the other hand, is more durable, fitting the bill for backpacking and mountaineering boots.
The shanks and plates are support components for the midsole and outsole, and both are found just in between. Shanks measure about 3-5 mm thick, covers the entire length of the midsole, and are responsible for the stiffness required by the midsole in load-bearing. Plates, on the contrary, are thin and semi flexible, found below the shank. They protect the feet from bruises obtained from obstacles along the way.
The outsole is the part which absorbs the most damage, thus considered to be the most durable, made even more by the components that support it from above. The only material used for this part is rubber, though sometimes there are additives applied, like carbon, to boost hardness for backpacking and mountaineering boots.