GRX RD-RX817 11-Speed Di2 Rear Derailleur
With an integrated chain stabilizer mechanism, the Shimano GRX RD-RX817 11-Speed Di2 Rear Derailleur provides a quieter experience and shifting security and precision on mixed terrain.
For rides on smooth surfaces, the derailleur features and ON/OFF switch for the chain tensioner. The RD-RX817 DI2 version offers the digital precision of SHIMANO electronic shifting and synchronized shifting. and is compatible with mtb cassettes with a 42T low sprocket max.
B-Stock - This product has one or more B-Stock units available. These units can be purchased at a discount (see option select). B-Stock units were returned from other customers and may have missing or damaged packaging materials. These units are otherwise as new. The full manufacturer warranty applies. Click Here for more information.
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.