The Shimano GRX FC-RX820-2 is the flagship 2x12-speed crankset in Shimano's dedicated gravel groupset. Built with Hollowtech II hollow aluminium construction and an asymmetric dual-BCD chainring interface, it delivers precise, confident shifting across 48/31T gearing — giving gravel riders the tight gear steps of a road drivetrain alongside the low-end range needed for rough terrain and long days in the saddle.

Highlights

• Hollowtech II construction: Hollow aluminium crank arms with integrated spindle maximise stiffness-to-weight and power transfer on every pedal stroke.
• 48/31T chainring combination: Tighter gear steps than a typical 2x road setup, yet a wide enough range for mixed gravel and climbing.
• Asymmetric dual BCD (110/80mm): Outer 110mm and inner 80mm bolt circles allow optimised chainring design for each position, improving chain retention and shift quality.
• Gravel-optimised Q-factor: 151mm Q-factor provides a wider stance than road cranks for stable pedalling and additional tyre clearance on rough surfaces.
• 47mm chainline: Sits 2.5mm wider than a standard road chainline, enabling larger tyre fitment while maintaining compatibility with 135/142mm rear disc hubs.
• Three crank arm lengths: Available in 170, 172.5, and 175mm to suit a range of rider proportions and fit preferences.
• GRX ecosystem integration: Designed to work seamlessly with FD-RX820 front derailleur, RD-RX820 rear derailleur, and ST-RX820 shifters.

Gravel-Specific Design

The FC-RX820-2 is engineered specifically for gravel riding and racing. The 2x configuration gives riders the ability to fine-tune cadence across variable terrain — maintaining tight gear steps for bunch riding on smoother roads while offering the low gearing required for technical climbs and loaded adventure riding. The wider Q-factor and chainline are purpose-built to accommodate larger gravel tyres without compromising pedalling efficiency.

Hollowtech II Technology

Shimano's Hollowtech II system integrates the spindle into the right crank arm, eliminating the traditional square-taper or spline interface. The result is a stiffer, lighter drivetrain connection that transfers power more directly to the chain. Installation requires a compatible Hollowtech II bottom bracket (sold separately).

Compatibility & Fit

The FC-RX820-2 is a 2x12-speed crankset compatible with Shimano GRX 12-speed drivetrains. Chainring BCD is asymmetric: 110mm outer / 80mm inner. Chainline is 47mm, suitable for 135/142mm rear disc hubs with chainstays greater than 415mm. Bottom bracket not included — requires a Shimano Hollowtech II bottom bracket. Compatible with 12-speed HG chains. Crank arm lengths available: 170mm, 172.5mm, and 175mm.