Why Is the Shimano Dura-Ace RD-R9250 the Fastest Rear Derailleur Shimano Makes?

The Shimano Dura-Ace RD-R9250 is a complete ground-up redesign that shifts 58% faster than the previous generation RD-R9150, housed in a compact Shadow RD low-profile body with a full carbon fiber cage that cuts weight without sacrificing rigidity. What sets the R9250 apart from all previous Di2 generations is the fully consolidated wireless hub built into the derailleur body: charging port, D-FLY Bluetooth LE and ANT+ connectivity, LED status indicator, and function button are all integrated, eliminating the need for a separate junction box entirely. A single cage length handles cassettes from 11-28t through 11-34t, covering criterium-specific close-range and climbing setups with one derailleur.

Part of the Shimano Dura-Ace R9200 semi-wireless Di2 system. The derailleur connects to the BT-DN300 battery via EW-SD300 E-Tube wire while shift commands arrive wirelessly from the ST-R9270 levers. Synchronized shifting, shift speed, and all settings are configurable via the E-Tube Project app over Bluetooth. Compatible with 12-speed Dura-Ace Di2 only. Not compatible with 11-speed Di2 or mechanical components. Cross-compatible with Ultegra R8100 Di2.