Di2: plug and play options abound
The big news is that Dura-Ace receives the E-Tube wiring that we first saw on Ultegra. The smaller wires and smaller, waterproof junctions are easier to install and use smaller holes in the frame.
The front junction box is now plug and play with a charging port built into the junction. No more need to pull off your battery to charge it. This is an especially nice feature when used in combination with Shimano’s new internal battery. Shimano is working with many bike manufacturers to help integrate the new battery into production bikes. The battery will also be available aftermarket, built into PRO seatposts.
The new wiring kits, specifically the new F-junction box mounted underneath the stem, will make it possible to run multiple accessory shifters. So a Di2 rider no longer has to choose between sprint shifters or the “Roubaix button.” For a hilly time trial, riders can now run a drop bar with a clip-on aerobar, with shifting available in both positions.
In addition to the current shift button offerings, Shimano will also be producing a set of single-button time trial shifters. Professional teams came up with the idea of one button per extension, both controlling the rear derailleur similar to the sprint shifters. The new shifter is designated the ST-9071.
Di2 shifters also now have a programmable shift function. The rider can choose whether he wants to be able to dump multiple gears while continuously holding a button down. The rider can also program the delay, that is, how long it takes to hold the button before it begins to dump gears.
Lastly, the new wiring is also ANT+ compatible and Shimano will produce a computer (likely FlightDeck labeled) to show battery life and gear options.
Both derailleurs are smaller than before and each of the Di2 parts has lost weight. The shifters have taller shift buttons and they are more distinct than before, making it easier to shift with bulky gloves in winter. In a small change, the wire for the front derailleur now enters at the back of the derailleur to better hide wiring behind the seat tube.