Rear Derailleur (1x)

RD-RX817 - Rear Derailleur (1x) image

If you've been looking at GRX Di2 components you may have seen that there are two rear deraileurs. This RD-RX817 and its lightweight cousin, the RD-RX815.

The RD-RX817 was developed by Shimano specifically for use in 1x bikes. This means that running this rear derailleur with a front derailleur is officially not supported. There are reports of users installing a front derailleur anyway, like this user on If you do, keep in mind that this is not Shimano approved and your experience (and possibly safety) could suffer.

This RD-RX817 has a total capacity of 31T, allowing you to run an 11-42T cassette. Its top sprocket max is 11T and the low sprocket max is 42T (min 40T).

Both GRX rear derailleurs feature a clutch mechanism, just like the Ultegra RD-RX805 and the mountain bike rear derailleurs. Shimano call this the chain stabiliser. It can be adjusted and prevents chain slapping (or worse, dropping your chain).

Details & Specifications

Model number:
318 g
E-Tube ports:
E-Tube Port type:
Rear Derailleur
GRX RX815 (Gravel)

Shopping links

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