Shimano GRX RD-RX827-SGS Di2 Wireless Rear Derailleur - 12-Speed Long Cage Shadow ES Black. The Shimano GRX RX827 Di2 Wireless rear derailleur paired with a 10-51t cassette (cassette sold separate) gives riders and racers the speed range and robustness to pursue any gravel challenge. With built-in automatic impact recovery an impact-deflecting shape and solid pulleys this derailleur stands up to hard impacts and still retains its lightning-quick shifting performance.

Fully wireless shifting built for rough gravel terrain

A wide link structure skid-plate design durable aluminum plate and solid pulley add robustness and longevity

Automatic Impact Recovery function instantly returns the derailleur to its original position after impact

Features Shimano Shadow ES: A slimmer stronger evolution of Shimanos pioneering chain-stabilizing Shadow RD+ concept

Tucked safely inside an enclosed space the battery won’t budge even in rough terrain while remaining easily removable for charging