Shimano ultegra di2 6870 11sp front derailleurthe di2 front derailleur's operation is pioneering, smooth shifting is guaranteed thanks to a microchip communication link with the gear levers'. '.strtoupper('w')hat'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'. '.strtoupper('t')he 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'. '.strtoupper('t')he 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.features compatibility 11 speed e tube di2 top gear teeth 46 53t maximum capacity 16t chainstay angle 61 66deg chainline 43.5 weight 162ga 2 year warranty is offered with all shimano products from chain reaction cycles 3 years on dura ace and xtr products..buy shimano components from chain reaction cycles, the world's largest online bike store.