Elite road racers demand reliable and precise shifting, 11-speed Dura-Ace R9150 delivers with its super-lightweight yet durable designSynchronized Shift designed, developed to choose the next biggest or lowest gear ratio irrespective of whether a gear change needs to be made by the front or rear derailleur,The Di2 front derailleur's operation is pioneering, smooth shifting is guaranteed thanks to a microchip communication link with the gear levers. What's more, 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 difference in the effort and time to actuate the shift between mechanical and Di2 is truly staggering,The 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 shifts,The 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 ahead,Braze-on fit as standard; if your bike does not have a braze-on mount seat tube adapters are available,11-speed E-tube Di2 compatible,Compatible with 50-55 tooth chainrings,Total capacity 16T,Front derailleur weight is 104 grams.