The Shimano RD-RX817 GRX rear derailleur is Shimano's first GRX Di2 rear derailleur. The 817 in the model name indicates that this is the 1x long-cage version of the GRX rear derailleur. It utilizes an adjustable chain stabilizer to prevent chain slapping and drops.
Using a front derailleur with the RD-RX817 is not supported by Shimano, so it can be used in a 1x configuration only. Its RD-RX815 sibling can be used with a front derailleur.
However, while not supported, it seems your bike will work if you install an RD-RX817 and a front derailleur. Whether or not this will be disabled in future firmware is anyone's guess.
Like other Shimano clutch derailleurs it has an ON/OFF switch that lets you switch the clutch on or off.
This rear derailleurs ensures silent and uninterrupted rear shifting on rough terrain, smooth and reliable mixed surface shifting.
It is compatible with any current road dual control lever and of course the GRX specific dual control levers.
Top sprocket: Max. 11T/Min. 11T
Low sprocket: Max. 42T/Min. 40T
Total capacity: 31T
Read how to install and set up this rear derailleur in our RD-RX805 / RD-RX815 / RD-RX817 rear derailleur installation guide.