US Patent 7451557 Article of footwear with a removable midsole element

An article of footwear is disclosed that includes an upper, an outsole, and a midsole. The upper is configured to receive a foot, and the outsole is secured to the upper. The outsole defines a plurality of apertures extending entirely through the outsole. In addition, the outsole has a ground-engaging surface positioned at a first elevation. The midsole is separate from the upper and the outsole. The midsole is also positionable within the upper such that a lower surface of the midsole extends into the apertures of the outsole and is exposed by the apertures. The lower surface is at a second elevation, the first elevation being less than the second elevation.