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Shimano's GRX Gravel Bike Components and Features
Modified at: May 23, 2024
Posted at: Jan 8, 2021
The following is a summary of Shimano's GRX lineup of components for gravel bikes, its features, and the advantages and disadvantages of choosing GRX.
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Table of contents
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What Is Shimano’s GRX Gravel-Specific Groupset?
Key Features of GRX
Shimano GRX is a component series specifically designed for the emerging category of gravel bikes, following Shimano’s established road and MTB components.
Gravel bikes differ from standard road bikes in terms of their intended terrain.
- Road bikes are built for paved roads.
- MTBs are built for rough, off-road trails.
- Gravel bikes are designed to handle both paved surfaces and moderately rough roads, making them a hybrid between road and mountain bikes.
The GRX series is optimized for this versatility, combining the best features of both road and MTB components.
GRX Lineup
Shimano’s road bike components come in a wide range of grades, with DURA-ACE at the top, followed by ULTEGRA and others—currently totaling seven levels.
Shimano Road Bike Components: Brand, Grade, and Identification
A summary of Shimano's road bike component brands, grades and how to identify them. The model numbers and features of each are also included.
As of 2024, however, Shimano’s gravel-specific lineup is unified under the GRX brand. Within GRX, there are five sub-series that represent different performance tiers:
- GRX Di2 12-speed
- GRX 12-speed
- GRX Di2 11-speed
- GRX 11-speed
- GRX 10-speed
Each sub-series offers different levels of performance and features, allowing riders to choose based on their needs and budget. The differences between each GRX series come down to four key factors:
- Number of gears
- Electronic shifting (Di2)
- Front single chainring compatibility
- Dropper post integration
All GRX lines use hydraulic disc brakes by default. There are no options for mechanical disc brake levers in the GRX series.
When GRX was first released, it was limited to 11-speed and 10-speed models. However, in September 2023, Shimano launched the new 12-speed GRX lines: the RX820 and RX610 series. Later, in May 2024, Shimano released the RX825 series, a 12-speed Di2 (electronic shifting) model, further expanding the lineup.
According to Shimano, the 12-speed GRX lineup is segmented by ride style:
- UNBEATABLE: GRX 1×12 (10-45T)
- UNSTOPPABLE: GRX 1×12 (10-51T)
- UNDROPPABLE: GRX 2×12
The main differences lie in the front gearing setup (single vs. double) and cassette range.
Note: The GRX 12-speed Di2 (RX825) is only available in a front double configuration.
| Model | Series | Gearing | Di2 | Front Single | Dropper Post Support |
|---|---|---|---|---|---|
| GRX Di2 12-Speed | RX-825 | 2×12 | ✅ | ❌ | ❌ |
| GRX 12-Speed | RX-820, RX-610 | 1×12, 2×12 | ❌ | ✅ | ✅ |
| GRX Di2 11-Speed | RX-815 | 1×11, 2×11 | ✅ | ✅ | ❌ |
| GRX 11-Speed | RX-810, RX-600 | 1×11, 2×11 | ❌ | ✅ | ✅ |
| GRX 10-Speed | RX-400 (some parts from RX-600) | 1×10, 2×10 | ❌ | ✅ | ❌ |
Differences Between GRX and Road Bike Components
The main differences between GRX and road bike components are:
- Supported tire size
- Supported cassette and chainring gearing
- Shape of the STI levers
GRX is designed to support wider tires, wider-range gearing, and lever shapes optimized for rough terrain, compared to standard road bike components.
Notably, the latest 12-speed GRX series (RX820 and RX620) includes rear derailleurs with significant range:
- The SGS model supports up to a 51T large cog
- The GS model supports up to 45T
- Both support 10T smallest cogs when using Micro Spline cassettes
This means you can equip your gravel bike with MTB-like gearing.
Compatibility With Road Components
GRX components are mix-and-match compatible with road bike components under certain conditions. According to Shimano’s compatibility charts, GRX can be used with current road components if the number of speeds matches, and as long as gear capacity stays within limits.
Additionally, components like cassettes and bottom brackets are shared between GRX and road groupsets, which means:
- You can integrate GRX parts into a road groupset
- You can incorporate road components into a GRX build
Because of this broad compatibility, GRX offers a high level of flexibility in building your ideal setup.
Shimano Road Components Compatible with GRX Gravel
Shimano's GRX series of gravel components can be used in combination with other road bike components, including tips on how to mix and match.
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Advantages of Choosing GRX
Wider Riding Versatility
GRX features hydraulic disc brakes across all models and supports wide-range cassettes, making it closer in nature to MTB components. However, since GRX is designed for drop bars, like road bikes, the ride feel remains distinctly road-like rather than MTB.
Its optimized STI lever shape, dropper post compatibility, and gravel-tuned gearing (cassette and chainring) allow for better performance on rough terrain, while still enabling high-speed cruising on paved roads. This makes GRX extremely versatile, combining the best of both road and off-road riding.
Supports Front Single for Fewer Shifting Issues
GRX supports 1x (front single) drivetrains, which simplifies shifting and reduces mechanical issues like dropped chains.
Front single setups are also easier to maintain and shift, making them ideal for riders seeking low-maintenance, easy-to-use drivetrains.
Advantages and disadvantages of front single
The "front single" without front shifting is being increasingly adopted in MTB and gravel road bikes. This section summarizes the advantages and disadvantages of the front single.
Disadvantages of Choosing GRX
Limited Low-End Options
When GRX was first introduced, it came with only three groupsets, due to its positioning in the new “gravel bike” category. Unlike road components, which span from entry-level to pro use, GRX initially had fewer options, limiting its accessibility.
However, with the release of 12-speed mechanical GRX in 2023 and 12-speed Di2 GRX in 2024, the lineup has expanded to five group levels (or seven variations when counting RX800 and RX600 separately for mechanical 11-speed), significantly improving availability and choice.
That said, GRX still sits slightly below the 105 price range, making it more affordable than DURA-ACE but still pricier than true entry-level groups like SORA or TIAGRA.
Requires Disc-Compatible Frames and Wheels
All GRX STI levers are hydraulic disc brake only, meaning your bike’s frame and wheels must support disc brakes.
While it is technically possible to combine GRX with a rim-brake road bike to build a gravel setup, a full GRX build will require upgrading the frame and wheels, which can significantly increase costs.
This has been an overview of Shimano GRX.
Gravel riding has seen a surge in popularity in recent years, and GRX can be seen as a “next-generation groupset” for this evolving segment.
Whether you’re upgrading a road bike to a gravel spec or building a complete bike around GRX, the customization flexibility makes it a very exciting option for riders.