The Dura-Ace Di2 12-Speed rear derailleur from Shimano has been completely overhauled by Shimano and compared to the 11-speed version now works wirelessly with Di2 STI levers. The rear derailleur featured synchronised shift that selects the most appropriate gear ratio whilst the electronic cables eliminate poor shifting caused by cable stretch and dirt.

As you would expect with Shimanos top of the line products from the Dura-Ace family, the new Dura-Ace Di2 12-speed rear derailleur is the lightest derailleur in the new 12-speed family, utilising lightweight materials including carbon and titanium.