Shimano Black Shimano GRX Di2 RX825 12s Shadow+ rear derailleur 2025

SHIMANO's GRX Di2 12-speed rear derailleur features a built-in wireless connectivity unit and charging port, ensuring fast and reliable shifting for mixed-terrain riding and easy recharging. Integrated SHADOW RD+ technology prevents chain slap and ensures precise shifting even on rough terrain. Thanks to built-in ON/OFF switch, wheel removal is easy too. The RD-RX825 is compatible with 11-34T and 11-36T 12-speed cassettes and supports Full or Semi-Synchronized shift modes, enhancing rider customization.

• Compact design with integrated wireless unit, charging port, and switch
• Fast and reliable shifting on rough terrain
• Adjustable chain stabilizer prevents chain slap
• SHIMANO SHADOW RD+
• Gravel-tuned clutch tension
• Switch stabilizer ON/OFF to match terrain: ON for gravel, OFF for smooth roads
• LED status indicator
• Battery indicator, pairing, adjust mode, etc.
• Max. front difference: 17T
• Total capacity: 40T
• Low sprocket: Max.: 36T, Min.: 34T
• Top sprocket: Max.: 11T, Min.: 11T
• Pulley: Guide pulley bearing
• Teeth: 11/13T
• Di2 connectivity wired
• Di2 shifting
• Bluetooth® LE custom (*1)|Adjust mode information
• Bluetooth® LE custom (*1)|Di2 battery level
• Bluetooth® LE custom (*1)|Gear position
• Bluetooth® LE custom (*1)|SHIMANO E-BIKE SYSTEMS data items (*3)
• Bluetooth® LE custom (*1)|Compatible with E-TUBE RIDE
• Bluetooth® LE custom (*1)|Compatible with E-TUBE PROJECT
• ANT private (*2)|Adjust mode information
• ANT private (*2)|Di2 battery level
• ANT private (*2)|Gear position
• ANT private (*2)|SHIMANO E-BIKE SYSTEMS data items (*3)
• Firmware update by E-TUBE PROJECT
• SD300 port
• LED for system status
• Charging cable: EW-EC300