The new Dura Ace from Shimano is answers the question of many pros and ambitious amateurs as to whether and how the current, immensely high level of performance could be further increased. Each individual Dura Ace R9100 component is designed to work as efficiently as possible with all other components of the system. This shows the core of Shimano's component-developed-as-a-system philosophy particularly clearly. The result is called SYSTEM SUPREMACY - the superiority of the system over the sum of the individual parts.The R9100 series enables optimum power transmission. This is achieved by its wider HOLLOWTECH II arm and a reinforced outer chainring on its unique four-arm asymmetric spider construction. The new R9100 cranks meet the highest standards in terms of stiffness and lightness.