The Shimano FC-RX820-2 31t Inner Chainring is the stock replacement inner ring for Shimano's GRX 820 2x12-speed crankset. Machined from anodized aluminum and built to Shimano's 80mm asymmetric BCD, it restores a worn drivetrain to factory spec without requiring a full crankset replacement.
This chainring covers the smaller end of a 2x12 GRX setup, pairing with the 48t outer ring to provide a compact low-end gear range well suited to climbing and variable terrain. Compatibility is specific to the FC-RX820-2 crankset, so confirming your exact crankset model before ordering is worthwhile.
Quick Facts
| Feature |
Specification |
| Compatibility |
Shimano GRX FC-RX820-2 cranksets |
| BCD |
80mm Shimano Asymmetric (inner position) |
| Material |
Anodized aluminum |
| Tooth Count |
31t |
| Drivetrain Speeds |
12-speed |