The latest firmware update for Di2 enables synchronised shift for Ultegra 6870 components. Synchronised shift lets the Di2 brain select the next available gear with one click of the lever. You're basically selecting a harder gear or an easier gear which may result in the Di2 brain making the selection by changing to the other front chain ring and a sprocket of the cassette. It's rather bizarre to watch it in action but it appears to work flawlessly.
The rider is in complete control as a double press of the function button on the junction box offers three modes:
- Manual mode - just as you've always had
- Semi-synchronised shift - uses both shifters but makes automated or ‘correction shifts’ on the rear mech to match your front shifts to allow for smooth changes and more a consistent cadence.
- Synchronised shift - one shifter utilises the full range of gears coordinating front and rear shifts for a seamless transition through the gear range.
To get synchronised shift you need the BT-DN110 cylindrical seat-post battery and the latest firmware. One other benefit of having the BT-DN110 battery is that, by using the matching EW-WU101 wireless unit, you can use the new Android and iOS eTube apps to customise your shift.