Elite road racers demand reliable and precise shifting 12-speed Dura-Ace R9250 delivers with its super-lightweight and compact design Synchronized 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 wireless communication 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 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 12-speed E-tube SD300 wire compatible