Why does dad's sole break easily?

Generally, the soles of old shoes are thick and mostly made of rubber. This thick foundation is very heavy, and frequent walking friction and bending can easily destroy the rubber structure, leading to rubber wear and fracture. Therefore, most old shoes are prone to rotten soles, which is also one of its shortcomings. And because of the walking posture, when walking, if it is an external figure, it will wear an external heel. Most people don't have an absolute sense of balance when walking, so it's normal for shoes to wear out, but because of its beauty and enhancement effect, many people will still buy them, so we can choose some old shoes with better soles, which are comfortable to wear and not easy to rot.