The Shimano GRX 11-speed Di2 rear derailleur integrates electronic shifting with silent and uninterrupted rear operation on rough terrain. An adjustable Shimano Shadow RD+ clutch prevents chain slapping and drops.â€¢Operates with Shimano Di2 for digital electronic shifting
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The product weight specified is an approximate weight based on the manufacturer's specifications (if available) or our measurement of one or two examples. For most products, the weight will typically vary by 5% to 10%.
Model Number: RD-RX817
Series: SHIMANO GRX DI2
Weight: 318 g
Direct Attachment: Yes
E-tube connector (pcs): 0
E-tube port (pcs): 1
Firmware update by E-TUBE Project: Yes
Fluoric coated link bushings: 4
Low sprocket: 42T (max) / 40T (min)
Sealed bearing guide pulley: Yes
Sealed bearing tension pulley: Yes
Top-Normal Spring Type: SHADOW RD plus
Top sprocket: 11T (Max/Min)
Total Capacity: 31T
Mount Type: Standard Rear Hanger
I installed this on my Co-Motion Tandem, running DI2 Ultegra 8070 group. First, being a tandem, a wide gear range is needed. Second, road DI2 only runs 2X drivetrains. Third, I use a FSA Gossamer triple crankset, using only the middle and big rings as a double. This means the smallest available chainring is a 39T ring. I run an 11-40 SRAM cassette. The GRX RD-RX817 11-Speed Di2 Rear Derailleur is spec'd to run an 11-40 or 11-42 cassette, but for a 1X drivetrain. Well, the drivetrain shifts super smooth now! It works flawlessly with the 2X drivetrain, including the auto shift functions. It's well worth the money.