Wireless Unit / Information Display – why get a D-Fly

Updated March 2, 2024 by BetterShifting Terry

If you're on 10-speed or 11-speed Di2, you may have been reading my posts on the Wireless Unit or Information Display and wondered whether or not to buy one. After all, it’s an optional component, costs about $85 / €85 and your bike will work just fine without it. In this post, I’ll discuss its features so that you can decide for yourself.

12-speed Di2: no D-fly required

Shimano's 12-speed Di2 (105, Ultegra, and Dura-Ace) groupsets come with BluetoothLE/ANT functionality out of the box, built into the rear derailleur. All D-fly features are supported without the need for a separate module.

You do not need a D-fly if you are on 12-speed Di2.

Wireless Unit, D-Fly and Display.. what’s the difference?

Shimano have been making Wireless Units for road bikes ever since the DURA-ACE 9070 series. The very first model was the SM-EWW01. They later released the EW-WU101 and the 2-port in-line EW-WU111 Wireless Unit.

While all of the above D-fly units are compatible with mountain bike Di2 systems, you are far more likely to see either the XT SC-MT800 or XTR SC-M9051 Information Displays on an MTB.

Besides the obvious differences (display vs not-a-display), it’s worth noting that all of these components can be used on road/mtb/gravel bikes. You can use an Information Display on your road bike – it replaces Junction A and the EW-WU111 Wireless Unit. You can use the EW-WU111 on your mtb. All of them offer exactly the same Bluetooth LE / ANT features.

Synchronized shifting on mountain bikes

Another difference is related to synchronized shifting. While road bikes only need updated firmware and either the BT-DN110 battery or BM-DN100 battery mount, mountain bikes also require a System Information Display in order to enable synchronized shifting.

wireless unit versions

What features? What can they do?

The Di2 wireless units and displays allow you to connect your Di2 system to plenty of Bluetooth/ANT compatible devices. They let you connect to your bike computers, including (but not limited to):

If you have a Di2 compatible device you can use it to view the current gear, gear ratio, Di2 battery level, and even use the buttons on your shifters to interact with the bike computer itself – change the display, current lap, zoom or current page. Most devices will also export gear and shifting data, allowing you to analyze that data using external apps or sites.

wahoo app gears

Lights… action

Connectivity is not just limited to bike computers. You can also connect your bike to lights, action cameras and of course your mobile phone or tablet.

action cam and lights

When paired with the Garmin Varia UT800 light for example, you can use the shifter buttons to turn the light on or off, or change the current light mode. If you own a Shimano CM-2000, CM-1100 or CM-1000 action camera you can start and stop filming without even having to touch the camera itself, just by pairing it with a Di2 system. Connectivity is not limited to these devices, but most lights/cameras do not support Di2 connectivity. Check your light/camera documentation to see whether it connects to Di2 via ANT or Bluetooth.

About the e-Tube app

Another thing the Wireless connectivity lets you do is connect to your mobile phone or tablet to use the Shimano e-Tube app. It lets you do everything the Windows application does, but without having to bring your laptop with you on a ride. This makes it really easy to change or tweak some settings as you go, deciding on the perfect setup for your bike while riding it. Some of the things you can do with the mobile app are:

  • Set up, change and tweak synchronized-shifting
  • View the installed components
  • View the battery level
  • Check components for errors
  • Update firmware
  • Save your favorite settings in presets

Should you get one?

In the end it’s up to you to decide whether or not the Wireless unit or Information Display is of use to you. Its day-to-day use is limited, especially if you do not own a Shimano action cam or compatible light. How often do you need to change settings when you’re out on the bike, really? What it does provide is statistics and a direct connection between your bike computer and Di2 system.

gear information on a wahoo elemnt BOLT

As for my opinion… I ride bikes equipped with the EW-WU111 Wireless Unit / D-fly and the SC-MT800 display and I love it. Having the battery level and current gear on your screen is great and if you’re a data-geek like me you’ll have a lot of fun looking at your shifting statistics after big rides like the Marmotte or Maratona. Would I pick the SC-MT800 over the EW-WU111 for a road bike? Not really... it does add some nice small bits such as pre-synchro-shift indicator sounds, but these units really belong on mountain bikes.

BT-DN110 / BM-DN100 required

The EW-WU111 / EW-WU101 wireless units are meant to be used with the BT-DN110 / BM-DN100 battery / mount and will not work with the older SM-BTR2, SM-BMR1 or SM-BMR2 batteries. The older SM-EWW01 will work with the older batteries, but only supports ANT+ (no BluetoothLE).

New or used? Amazon or eBay?

Whether you should buy a new or pre-owned device depends on what device you’re after. The Inline Wireless unit found on road bikes generally doesn’t wear or degrade with use, so you might as well buy it second hand. If you’re looking to buy the Information Display you have the state of the screen to consider. Just like your mobile phone display, the Di2 Information Display will not stay in pristine condition forever. Before you buy one off eBay have a good look at the photos and check for scratches.

I’ve added shopping links for your convenience – and using the links below will earn the site a small commission (at no cost to you). Of course it’s up to you to decide where to buy your hardware. Other popular shops are ChainReactionCycles, Wiggle, Mantel, bike-components and bike-discount.

BetterShifting Terry

About the Author - BetterShifting Terry

I enjoy playing with bike tech - both bike building and wheel building, bike maintenance and of course, Di2. Besides writing content and working on the technical side of BetterShifting, I also work as a Software Developer in The Netherlands. Read more on the About this site page.

Ko-fi button

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