
Installation Guide: RD-RX805 / RD-RX815 / RD-RX817 Di2 Rear Derailleur
Read how to install the RD-RX805 / RD-RX815 / RD-RX817 Di2 rear derailleurs.
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 bikeforums.com. If you do, keep in mind that this is not Shimano approved and your shifting quality 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).
Read how to install the RD-RX805 / RD-RX815 / RD-RX817 Di2 rear derailleurs.
Indexing, trimming, or fine-tuning Di2 rear derailleurs is done through micro-adjustment. Read how to set up your Di2 rear derailleur perfectly and ride without those grinding noises.