Sidi avast rain shoes the reinforced heel keeps the foot in a optimal position and avoids the shoe being deformed by extreme performance or prolonged pressure replaceable heel pad for walkability sidi cycling shoes include a replaceable polyurethane heel pad millenium 3 sole the millennium 3 sole is a sleek modern redesign of the millennium 2 sole by fortifying the sole with carbon fiber sidi designers have created a sole that improves on the technical characteristics of the previous nylon