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GRX RD-RX825 12-Speed Di2 Rear Derailleur

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Why We Like The Shimano GRX RD-RX825 12-Speed Di2 Rear Derailleur

For fast, reliable shifting during our mixed-terrain riding adventures, Shimano brings us the new GRX RD-RX825 12-Speed Di2 Rear Derailleur, complete with a built-in wireless connectivity unit and charging port for easy operation and recharging. SHIMANO SHADOW RD+ chain stabilization helps prevent chain slap to allow us to continue to shift accurately as we ride over rough terrain, while the switch stabilizer features an ON/OFF switch to match the terrain and ease wheel removal. Compatible with 11-34t and 11-36t 12-speed cassettes, this wireless rear derailleur is ready to be added to our dream gravel setup. 


  • A 12-speed Di2 rear derailleur optimized for mixed-terrain riding
  • Built with a compact design with an integrated wireless unit, charging port, and switch
  • Shimano Shadow RD+ minimizes distraction for a quieter drivetrain
  • Features a switch stabilizer with an ON/OFF switch to match the type of terrain
  • An LED status indicator lets us know when to charge our system
  • Chain slap is prevented with an adjustable chain stabilizer
  • Top sprocket maximum and minimum of 11t
  • Low sprocket maximum of 36t with a minimum of 34t
  • Item #SHIU1NC
Cassette Range
11-34t and 11-36t 12-speed cassettes
Claimed Weight
Manufacturer Warranty
2 years

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