What Is It?
The Shimano ST-RX400 Left Hydraulic Brake/Shift Lever is a GRX Dual Control Lever designed for 2×10-speed gravel drivetrains. Combining hydraulic disc braking with front shifting in a single ergonomic unit, it is engineered specifically for gravel, adventure, and mixed-surface riding.
The left-hand lever controls the front derailleur (2-speed) while providing powerful and consistent hydraulic braking using Shimano Mineral Oil. Its gravel-specific ergonomics, textured hood, and reach adjustment deliver excellent comfort and control on rough terrain, whether riding on gravel roads, bikepacking routes, or everyday commutes.
Key Benefits
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GRX Dual Control Lever: Integrates hydraulic braking and 2-speed front shifting into one compact unit.
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Hydraulic Disc Braking: Delivers powerful, consistent braking with excellent modulation in all weather conditions.
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Gravel-Specific Ergonomics: Raised hood profile and textured surface improve grip and control on rough terrain.
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Reach Adjust: Allows the brake lever reach to be adjusted for different hand sizes and rider preferences.
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Light Front Shifting: Provides smooth and reliable operation of Shimano GRX 2x front derailleurs.
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Shimano Mineral Oil System: Low-maintenance hydraulic system with consistent braking performance.
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Premium Build Quality: Aluminium brake lever with an engineering composite bracket for strength and durability.
Specifications
| Specification |
Details |
| Product |
Shimano ST-RX400-L |
| Series |
GRX RX400 |
| Position |
Left |
| Brake Type |
Hydraulic Disc Brake |
| Shifter Type |
Dual Control Lever |
| Front Shifting |
2-Speed |
| Rear Shifting |
N/A (Left Lever) |
| Brake Fluid |
Shimano Mineral Oil |
| Recommended Brake Caliper |
BR-RX400, BR-RX410 |
| Brake Hose Compatibility |
SM-BH90-JK-SSR / SM-BH90-J-SSR |
| Reach Adjust |
Yes |
| Clamp Diameter |
23.8–24.2 mm |
| Lever Material |
Aluminium |
| Average Weight |
Approximately 306 g |
Compatible Components
The Shimano ST-RX400-L is compatible with:
- Shimano GRX FD-RX400 2-speed front derailleur
- Shimano GRX BR-RX400 hydraulic brake caliper
- Shimano GRX BR-RX410 hydraulic brake caliper
- Shimano 10-speed GRX RX400 drivetrain components
- Shimano SM-BH90 hydraulic brake hoses
- Shimano Mineral Oil brake systems
Who Is This Best Suited For?
The Shimano ST-RX400 Left Hydraulic Brake/Shift Lever is ideal for:
- Gravel riders
- Adventure cyclists
- Bikepacking enthusiasts
- Cyclocross riders
- Endurance road cyclists
- Mixed-surface commuters
- Riders building or upgrading a Shimano GRX RX400 2×10 drivetrain
- Cyclists seeking reliable hydraulic braking with gravel-specific ergonomics
Compatibility Note: The ST-RX400-L is designed specifically for Shimano GRX 2×10-speed drivetrains and controls the front derailleur only. It is intended to be paired with the ST-RX400-R right-hand lever, FD-RX400 front derailleur, compatible 10-speed Shimano cassette and chain, and BR-RX400 or BR-RX410 hydraulic brake calipers for optimal performance.
