The steel shank as a “backbone” of the shoe is a girder that connects the heel to the sole. It is located between the outsole and the insole of a leather shoe, which is not visible from the outside, but it plays an important role in determining the interior quality of a shoe. Under the condition that areas of sole and heel are the same, whether or not the leather shoes are stable on the feet depends on the function of the steel shank.
Not only does it has enough strength and rigidity to feature footwear a good-looking appearance, but it also ensures a certain elasticity to meet comfortability during wear. If the steel shank is too soft, the heel will skew towards different directions in walking to uglify the appearance, resulting in spraining the ankle and intensifying fatigue. If the steel shank is too hard, it will be uncomfortable for the wearer, and it is easy to be broken. If steps are not stable, It may lead the wearer to slip, even brings further danger. In a word, flexural rigidity is an important safety index of leather footwear.