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