Elite road racers demand reliable and precise shifting. The Shimano Dura-Ace R9150 delivers with its super-lightweight and compact design. Synchronized Shift is designed to choose the next biggest or lowest gear ratio, regardless of whether a gear change needs to be made by the front or rear derailleur. The Di2 front derailleur's operation is pioneering, with smooth shifting guaranteed thanks to wireless communication with the gear levers. Shifting the rear derailleur automatically trims the front derailleur. The biggest difference you will notice is just how much quicker and effortlessly smoother shifting on the front chainrings is, even under load. The removal of traditional mechanical cables in favor of electrical wires eliminates poor shifting caused by contaminants, corrosion, and stretching, providing effortless gear shifts. The front derailleur also trims automatically, with the cage moving in response to the position of the rear derailleur on the cassette.