The Shimano Ultegra FD-R8150 Di2 12-Speed Braze-On Front Derailleur uses pioneering Shimano technology. Smooth shifting is guaranteed thanks to wireless communication with the gear levers.Shimano Ultegra FD-R8150 Di2 12-Speed Braze-On Front Derailleur FeaturesFull and semi synchronized shifting programable, Synchro shift compatible meaning a single shifter can control both front and rear shifting which can be fully custom tuned to your riding preferences. Semi synchronized shifting means when a front shift is made the rear mech will automatically correct to the appropriate ratioThe removal of traditional mechanical cables in favour of electrical wires not only eliminates poor shifting caused by contaminates, corrosion and stretching but provides effortless gear shiftsThe front derailleur also trims automatically; the cage moves in response to the position of the rear derailleur on the cassette to ensure no chain rub and a quiet unobtrusive ride, enabling you to concentrate on the road aheadDesigned to work with the wider gear pitch spacing Shimano chainsets without sacrificing shifting performance on bikes with 135 / 142 mm O.L.D.Braze-on fit as standard; if your bike does not have a braze-on mount seat tube adapters are available12-speed E-tube SD300 wire compatible