The Shimano GRX FC-RX820-1 12-Speed 1x Chainring 42T is a genuine Shimano replacement chainring designed for GRX FC-RX820 single-ring cranksets. Built specifically for gravel and cyclocross use, it combines low weight, high rigidity and secure chain retention for efficient power transfer across fast, rough and muddy terrain.
Featuring Shimano’s thick-thin tooth profile and compatibility with HG+ 12-speed chains, this 42-tooth chainring is engineered to keep the chain securely engaged while delivering smooth pedalling and dependable drivetrain performance under load.
Genuine Shimano GRX Replacement Chainring
This is a genuine replacement chainring for the Shimano GRX FC-RX820-1 1x12 crankset, making it the ideal choice when replacing a worn or damaged original chainring.
Using genuine Shimano components helps maintain correct fit, drivetrain compatibility and the performance characteristics intended for your GRX setup.
42T 1x Gravel Gearing
The 42-tooth configuration is well suited to riders who prioritise higher cruising speeds and fast gravel riding while still retaining the simplicity of a 1x drivetrain.
Compared with a smaller chainring, the 42T option provides a taller overall gear, making it a strong choice for flatter gravel routes, racing, cyclocross and riders who spend more time riding at higher speeds.
Thick-Thin Tooth Profile
Shimano’s thick-thin chainring tooth design improves chain retention, helping reduce the risk of chain drops when riding over rough or uneven terrain.
This added security is particularly useful for gravel and cyclocross, where vibration, mud and rapid changes in terrain place extra demands on the drivetrain.
Designed for Shimano HG+ 12-Speed Chains
The chainring is designed to work with Shimano HG+ 12-speed chains, helping deliver efficient power transfer and consistent engagement.
The chain and chainring interface are optimised to work together as part of Shimano’s 12-speed GRX drivetrain system.
Lightweight Aluminium Construction
Manufactured from lightweight aluminium, the GRX FC-RX820 chainring provides the stiffness required for efficient pedalling while keeping unnecessary weight to a minimum.
Anodised teeth help improve durability and resistance to wear, making it suitable for regular riding in demanding gravel and cyclocross conditions.
Key Features
- Genuine Shimano GRX replacement chainring
- Designed for FC-RX820-1 1x cranksets
- 42T size
- 12-speed compatible
- Compatible with Shimano HG+ 12-speed chains
- Thick-thin tooth profile for improved chain retention
- Lightweight aluminium construction
- Anodised teeth for improved durability
- 110mm BCD
- 4-arm fitting
- Designed for gravel and cyclocross use
- Colour: Black
- Shimano part number: Y0SB98020
Why Choose the Shimano GRX FC-RX820-1 42T Chainring?
The Shimano GRX FC-RX820-1 42T chainring is the correct genuine replacement for riders who want to restore or maintain the performance of their GRX 12-speed 1x drivetrain.
Its lightweight aluminium construction, durable anodised teeth and secure thick-thin profile make it an excellent choice for gravel riders and cyclocross racers who want reliable chain retention, efficient power transfer and a slightly higher gearing option for faster riding.