The Shimano "D-Fly" Shows What Gear You are in on Your Di2 Bike

By Jim Weaver
Service Manager, Fit Werx, VT

Shimano recently released a new optional item to its Ultegra 6870 and Dura Ace 9070 Di2 electronic shifting systems.  Commonly known as the “D-Fly”, or in Shimano parlance, the SM-EWW01, this small device is a transmitter that allows the Di2 system to communicate with many of the latest generation of cycling computers that operate on the ANT/ANT+ protocol, such as the Garmin Edge 1000, Garmin Edge 810, Garmin Edge 510 or Magellan Cyclo 505HC.  This small transmitter plugs into the E-Tube cable that runs to the rear derailleur of the Shimano Di2 system. A new short cable is then used to connect the D-Fly unit to the rear derailleur. So, the basis has now been established for the shifting system to communicate with your cycling computer.

So what does this Shimano D-Fly device do? Well, for now, it allows compatible computers to display your current gearing combination, as well as your Di2 battery status. Like Shimano’s original Flight Deck system from the turn of the century, there is no need to look away from the road to see what gear you are in with the Shimano D-Fly. With the Shimano D-Fly, there is less chance of going out on a ride with a low battery charge as well as the battery status is staring you in face on your computer screen. So, both of these displays are useful and were missed, but are hardly revolutionary. Both Shimano and Campagnolo had popular bike computers that displayed gearing years ago (Flight Deck and ErgoBrain), but both systems were finicky and back burnered. So, it is nice to have these basic items from the past back and these alone make the D-Fly a very worthwhile installation for many folks. However, what the D-Fly currently offers is only the beginning. Shimano appears to have much bigger plans for this device. For example, on top of each of the Dura Ace 9070 shift levers is a button that heretofore had no use. Shimano’s latest firmware update for their Di2 system activated that button so that it will allow a rider to control their bike computer from the lever.  Hmmm, haven’t we seen this before too?  Yes.  However, this is where the Flight Deck similarities end.  What D-Fly will allow for in the future is app development that can control exactly what this button does. Once these apps have been developed and released, the rider will be able to switch screens and monitor everything going on with your Di2 bike without taking your hands off the brake hoods. Safer and more data – a good combination.

I am sure that Shimano’s engineers are beavering away to come up with other useful ways the D-Fly can be useful. For example, right now, performing diagnostics on the Di2 system, or changing the operating parameters of the system (such as adjusting how fast the rear derailleur shifts, or what shift buttons control what derailleur functions), requires connection of the system to Shimano’s dedicated SM-PCE1 PC Link interface, and then connecting that to a computer that has the correct Shimano software installed. Using the small receiver that is compatible with many ANT/ANT+ computers (a Garmin 1000, for example), you might be able to allow the Di2 system to communicate directly with a laptop or PC in the future. This could allow the diagnostic program to be run without the need for the PC Link interface and thus make service and adjustment easier. The newest bike computers, such as the Garmin 1000, or Magellan Cyclo 505HC, can now communicate via Bluetooth (they can “talk” to your phone) as well. This communication ability, coupled with the correct app on your phone, could lead to being able to run diagnostic programs, or make system changes, thus eliminating the need for a PC or laptop interface altogether. This is just speculation on my part, but the D-Fly opens a lot of possibilities that are far beyond my somewhat Luddite imagination is able to conceive at this moment.

The Shimano Di2 D-Fly computer link is just another example of how Shimano has built flexibility and expandability into its Di2 system. Once the basic mechanical bits (i.e. derailleurs and shifters) were designed and built, the only limitations are software and the imaginations of the engineers. Is an automatic shifting system very far into the future, controlled by your bike computer? Time will tell.

Interested in getting a Shimano D-Fly to allow your Garmin cycling computer to display your gearing on your Di2 bike or just have questions? Contact Fit Werx near New York City in Bergen County, NJ; Peabody or Lexington, MA or near Stowe and Burlington, VT in Waitsfield.