12-speed Rear Derailleur installation and adjustment guide
This page shows you how to install a 12-speed Di2 road rear derailleur and how to the B-screw, limits, and fine-tune the shifting using micro-adjust.
Rear Derailleur
GRX RD-RX825
This twelve-speed gravel rear derailleur features a charge port, LED, function button and an EW-SD300 type port used to connect the derailleur to the battery.
Both the rear derailleur and the front derailleur connect to the battery using a wire. The shift levers send their shift commands to the rear derailleur wirelessly.
Since this is a gravel rear derailleur, it also has a clutch mechanism that can be switched on/off. When turned on, this mechanism will ensure proper chain retention and smooth shifting on rough terrain.
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Just like the 11-speed GRX rear derailleurs, this 12-speed RD-RX825 falls into the road category. This means that it's fully compatible with other 12-speed Di2 groupsets. If you want to build a 12-speed road bike with a clutch rear derailleur, you can!
Specifications
- Model code
- RD-RX825
- Series
- GRX RX825
- Weight
- 310g
- Number of buttons
- 1 (function button)
- SD300 ports
- 1
- Max front difference
- 16T
- Total capacity
- 41T
- Low sprocket max
- 36T
- Low sprocket min
- 34T
- Wireless connectivity
- Bluetooth / ANT
- Charging port
- Yes
- Charger
- EW-EC300
- RD Type
- Shadow RD+
- Clutch
- Yes
Related components
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Adjust 12-speed Di2 rear derailleur shifting and limits
This page shows you how to set up your 12-speed rear derailleur B-screw, limits, and fine-tune the shifting using micro-adjust. The process is similar to that of the 10-speed and 12-speed rear derailleurs.
Understanding Di2 derailleur specifications
What is a rear derailleur's total capacity, really? Why is there a top sprocket minimum? And what about front derailleurs? Chain line, total capacity, Top gear teeth? This page explains all of those, and more.
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