Dura ace 9100 11 speed double groupset system engineering at its peak each of the components magnifies the qualities of the others for an unparalleled level of performance optimizing input to maximize output thats how it achieves supremacy the concept behind of the dura ace 9100 groupset was to examine and improve every component to optimize the input and maximize the output the result is less energy loss between what the rider puts in and what goes out at the wheels the chainset has bee