The difference in the effort and time taken for front shifts between Dura-Ace mechanical and Di2 is truly staggering: with programmed automatic motion at the touch of a switch the Dura-Ace Di2 front derailleur isquick, smooth and effortless, making for unmatched drivetrain efficiency 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 High tolerance cold forged aluminium and composite construction Brze-on fit as standard; if your bike does not have a braze-on mount seat tube adapters are available 10-speed Dura-Ace Di2 compatible Front derailleur weight is 124 grams