Shadow Rear Derailleur (12 speed)

DURA-ACE RD-R9250

This DURA-ACE Rear Derailleur is part of the 12 speed system, semi-wireless, and uses a new battery, the BT-DN300.

It features a charge port, LED, button, and an EW-SD300 type port used to connect the derailleur to the battery. Both the rear derailleur and the front derailleur connect to the battery using a wire.

The shift levers send their shift commands to the rear derailleur wirelessly.

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These 12-speed derailleurs use the same charger as the new Di2 power meters, and perhaps even better: the port cover can be replaced when broken.

LEDs and button cheat sheet

Keep having to go back to the manual to read what the LEDs mean or what the button does? Download my Cheat Sheets, print them, and keep them close to your bike. That way you'll never have to look for the manual again.

Di2 Cheat Sheets.

Crash Mode Reset

Since the main junction functionality has moved to the rear derailleur, Shimano also changed the method of getting out of crash mode. Pressing the button on the rear derailleur would be hard during a race, so you can now shift out of crash mode.

To get out of crash mode on 12-speed road bikes, shift up and down the entire cassette. This video by Rides of Japan explains it well:

Improved chain guard

Early versions of the RD-R9250 had an issue where on some occasions the chain would at times touch the chain guard - that small tab between the two jockey wheels. This didn't impact shifting, but it did cause excessive drivetrain noise and clicking.

Shimano quietly updated the RD-R9250 outer plate to include a slimmer chain guard, fixing the issue.

R9250 chain guard

If you are experiencing excessive drivetrain noise on your R9250 bike, be sure to check the chain guard for impact marks. Your bike shop will be able to get a new one from Shimsno. Alternatively, you can file a bit off so that the chain no longer hits the tab.

The updated chain guard looks like this:

RD-R9250 improved chain guard

The part number for the new outer plate is Y3GK98040 - exactly the same as the original version of the outer plate. However, sometimes the new part is also referred to as "R9250pcage".