Shimano's Dura-Ace FCC Leak Is Going to Disappoint a Lot of People

We have direct confirmation of two hunches from our previous Shimano Dura-Ace R9300 coverage: the unreleased next-generation Shimano groupset will be direct mount and semi-wireless.

After we shared images of the system being tested in the wild at the Vuelta, complete with wires, some readers hypothesized that perhaps everything was not as it seemed. Theories persisted that visible wires, similar to the current Shimano semi-wireless design, could be there only as part of the testing. Surely Shimano would go full wireless when the system was actually ready to ship to consumers?

Now we can put that theory to rest as we have images leaked from the FCC filing required for all products sold with radio communication in the US. The images posted on the Weight Weenies forum include the rear derailleur motor and electronics with a power cable port, along with the internals for the dual control levers, but they do not include a front derailleur. That makes sense given the front derailleur does not have wireless communication capabilities in the semi-wireless system and therefore needs no FCC certification.

The other confirmation we can see here is that Shimano is moving to a direct mount interface for the chainring. Previously, as in the current model, the drive-side crank arm, the 24mm steel spindle, and the 4-arm spider are a single, permanently integrated unit. The four asymmetrical arms that the chainrings bolt onto are physically forged as part of the right crank arm; you cannot remove or swap the spider.

The reason this all matters is the Shimano power meter. Right now, it doesn’t work. It’s possible that part of the challenge Shimano has had is the integrated spider. This change also simplifies manufacturing and makes it easier for consumers to swap parts, so it’s a benefit regardless of the exact reasons.

There is one concerning detail on display, though. On that rear derailleur unit, the charge port is visible, and it’s different. The current design uses 4 pins in a single line. The new system shows a unit with 4 pins in a square design. That will mean a new charging cable, and you can also see a charging port on the crank arm that’s different. It appears we are looking at a doubling down of wires and internal batteries, and it’s coming with new charging cables.

As we covered previously, it is also coming with an extra cog as Shimano moves to 2×13. Shimano is not the first company to offer a 2×13 system, with Campagnolo having already brought it to market, but this update still represents the largest groupset manufacturer making the jump. It also appears that both a 34- and 36-tooth max cog will be available, as there is an appropriate spoke protector for the recently released R9370 wheelset lineup. Note the handy circle from the Weight Weenies forum.