A tunable rigidity insole with interchangeable stiffeners, comprising:
- an arch pad main body having a plurality of first engaging holes, a plurality of second engaging holes and a plurality of third engaging holes;
- and
- a first rigid stiffener, a second rigid stiffener and a third rigid stiffener;
- wherein one or two of the first rigid stiffener, the second rigid stiffener and the third rigid stiffener is assembled into a bottom surface of the arch pad main body, and after assembling, the first rigid stiffener supports a lateral longitudinal arch of a sole, the second rigid stiffener supports a central arch area of a sole and the third rigid stiffener supports a medial longitudinal arch of a sole respectively;
- wherein the first rigid stiffener includes two first engagement members at either end thereof, the second rigid stiffener includes two second engagement members at either end thereof, the third rigid stiffener includes two third engagement members at either end thereof;
- wherein each of the first, second and third engagement members includes a rod having a back wall, wherein each of the first engagement members includes a first engagement extension extending substantially in a direction away from the back wall of the rod of the first engagement member and toward the first engagement member at the other end of the first rigid stiffener, each of the second engagement members includes a second engagement extension extending substantially in a direction away from the back wall of the rod of the second engagement member and toward the second engagement member at the other end of the second rigid stiffener, each of the third engagement members includes a third engagement extension extending substantially in a direction away from the back wall of the rod of the third engagement member and toward the third engagement member at the other end of the third rigid stiffener;
- wherein the first, second and third engagement members of the first, second and third rigid stiffeners correspond to the first, second and third engaging holes respectively in order to be engaged with the arch pad main body;
- wherein one of the first engaging hole, the second engaging hole, and the third engaging hole includes a flange adjacent to a surface of the arch pad main body, and a length of a surface opening on top of the first, second, and third engaging holes enclosed by the flange is less than a length of opening at the bottom of the first, second, and third engaging holes, to thereby be closely engaged with the first, second, and third engagement extensions and the first, second, or third engaging holes without separation;
- wherein the rod portion of the first, second, or third engagement members becomes deformed and bent while the first, second, or third engagement extensions are made to enter the surface opening on top of the first, second or third engaging holes, a gap being formed between the back wall of the first, second, or third engagement members and the first, second, or third engaging holes;
- wherein the material of the first rigid stiffener, the second rigid stiffener and the third rigid stiffener is at least one selected from the group consisting of glass fiber, blended carbon fiber, a metal material and combinations thereof.