Shimano

Di2 D-Fly Wireless Transmitter Unit

The electronic revolution is in full swing, and now it will be televised. Well, not televised exactly, but it will appear on your bike's computer screen courtesy of the Shimano Di2 D-Fly Wireless Transmitter Unit. Not even the Italians can keep up with Shimano's electronic innovations, and — while other companies are still preparing to release an electronic group or fine tune what they've already got out — the Japanese drivetrain experts continue to revolutionize cable-free setups.

This little guy is like a black box for your bike, feeding data via a proprietary ANT connection from your derailleurs to your computer so you can monitor drivetrain metrics like gearing and battery life. The latter is especially useful, as it's looking to be the most effective way the industry has come up with to ensure you won't unexpectedly run out of juice during the trip home. It also measures general riding metrics, so you're not sacrificing the functionality of a normal computer by adding drivetrain info to your cockpit. Your pedal revolutions will also be televised.

The Di2 D-Fly Wireless Transmitter Unit is compatible with Shimano's three E-tube Di2 groups: Dura-Ace 9070, Ultegra 6870, and the 10-speed Ultegra 6770. It transmits to Shimano's own PRO computer, as well as Garmin and Magellan computers. It's also an unobtrusive little device, measuring 38 x 25 x 12.5 millimeters with a claimed weight of less than five grams.