Shimano’s Di2 Synchro Shift was debuted on the electronic M9000 XTR group and allowed riders to program the front and rear derailleurs to work in combination with a single shifter. Synchro Shift does this by controlling the whole transmission with just one of the crossover shifts coming at predetermined gear ratios, whereas a typical multiple-chainring drivetrain for road or MTB requires separate shifters for the front and rear derailleurs,
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The latest Dura-Ace R9150 brought this functionality to the road, but unfortunately current Dura-Ace 9070 and Ultegra 6870 users missed out, until now. The update will arrive as part of Shimano's latest internal battery and a firmware update through the E-Tube app.
The new BT-DN110 internal battery contains a memory chip that can handle the additional processing power required to deal with multiple shift patterns and the customization that Synchro Shift offers. Shimano also tells us that the BM-DN100 external battery mount can activate Synchro Shift too.
You’ll need a compatible front (FD-6870 / FD-9070 / FD-9150) and rear (RD-6870 / RD- 9070 / RD-9150) derailleur, and to run a firmware update on the battery through a wired connection to your PC or Bluetooth connection to the E-Tube app.
Once everything is up to date, there will be three shift modes; fully synchronised, semi-synchronised and the conventional manual shift mode, which can be cycled by pushing the button on the junction box.
While the full Synchro Shift mode only requires one shifter to utilise the full range of gears coordinating front and rear shifts for a seamless transition through the range, the Semi Synchro still uses both shifters but makes automated or ‘correction shifts’ at the back to match your front shifts and to allow for smooth changes and more consistent cadence.
Each mode is customisable in the E-Tube app meaning you can choose different shift patterns and personalise gear mapping to your specific riding style. So, you can tell the system how many gears at the rear to compensate with when you shift from the big cog to the little ring or define which cog at the rear you want the front derailleur to shift up or down.
While Synchro Shift won't be for everyone, for those using TT, sprint, and climbing shifters this functionality seems pretty nifty.
Shimano says the addition of Synchro Shift to its road groups is to complement not replace manual shifting and even in full Synchro Shift mode riders still have full control over the front shifter.
Available now, the internal BT-DN110 battery will set you back €130 / £140 / $160 / AU$219, and the BM-DN100 version will cost €105 / £100 / $104 / AU$159.