The reasons are as follows: There are three purposes of wearing cycling pants: reducing wind resistance, increasing the comfort of the buttocks and seat cushion, and reducing friction. The last one: reduce friction. The reason for reducing friction is that long-distance cycling pants rubbing against the skin for a long time will cause different degrees of inflammation or other skin problems, and the material of cycling pants can effectively reduce friction. , and if you wear underwear again, the effect of reducing friction of cycling pants will be isolated, and it will not work. Moreover, the underwear is generally made of cotton, which has poor perspiration function, humidity and large friction. Harmful to the human body.