Wow!  The revolutionary Dura-Ace Di2 electronic shifting option for triathletes and time trialists eliminate the need to change hand positions for shifting. The electronic system is linked and you can execute gear shifts from the base bar or aero extensions which will save time and energy so you can focus on pedaling to your hearts content. The increased accuracy, smoothness and reliability of electronic shifting makes gear changes faster and eliminates missed shifts.

Designed exclusively for triathletes and time trialists, the new system eliminates the need to change hand positions during shifting.  Riders can change gears at the base bar (ST-7971) as well as the bar extensions (SW-7971) because the system in linked.