CORE MTB VALUES. The Carbide R is an XC shoe with the comfortable, supportive fit found in our premium shoes, combined with a nylon and rubber co-molded outsole. This results in impressive durability, grip, and traction in rocks and mud. The upper is made of supple synthetic leather with three wide straps that allow easy fit adjustments, while a supportive EVA footbed enhances comfort. A stout injected nylon sole helps transfer power to the pedals instantly, enhancing your connection to the bike.