Ask a Mechanic: Installing Shimano’s D-Fly Unit on Di2 Systems

Donald wants to know, “What does Shimano’s D-Fly unit do and how is it installed?”

Along with the proliferation of electronic drivetrains comes the opportunity for new ways to interact with your bike. One of the latest accessories to enhance your Shimano E-Tube Di2 electronic shifting experience is the D-Fly wireless unit. Although adding this unit won’t give you wireless shifting and operation of the components, it does offer some cool options for people using a wireless ANT+ computer. The D-Fly unit will currently enable you to view battery life and gear selection on your compatible computer, and the unit’s capabilities are rumored to soon expand. Wireless drivetrain control and phone/computer app compatibility are only a matter of time. The latest firmware for the 9070 Dura-Ace shifters allows you to take advantage of the buttons that are on top of the hoods that many people may not even know exist. Those buttons allow riders to control their computer without removing their hands from the controls. More apps and even wireless desktop connection are on the horizon, so the possibilities are endless.

The D-Fly unit can be installed anywhere in the Di2 system—which requires an additional wire—but is most commonly placed on the drive-side seat stay with the rear derailleur. To wire the D-Fly into your Di2 system, simply unplug the wire from the component you are going to place the d-fly unit in line with. Now, plug that wire into the D-Fly, along with the additional wire you purchased, and reconnect the new wire to the original component or junction box.

Of course, above the dropout isn’t the only place you can place the D-Fly unit. If your Di2 system is wired internally, and there is a spot in the frame where you can get the D-Fly unit inside, it can be placed in line with a junction box inside of the frame as well. There are countless mounting options to try and hide the unit in other places on the framel, like on the stem, or seat tube, or anywhere else an E-Tube wire is nearby. Get creative and find a solution that works best for your particular frame and bike set up.

That’s all there is to it. Be sure to keep your components and D-Fly unit up to date with the most current firmware to take advantage of all the capabilities of the system as they are developed. Check the Shimano E-Tube Project website for firmware updates. Remember, Art’s Cyclery updates the firmware on all applicable Shimano Di2 products the same day they are shipped out.