Shimano has launched the world’s first dedicated family of gravel and adventure components known as GRX.
The GRX offers RX800, RX600 or RX400-series components with 1×11, 2×11 and 2×10 drivetrains and mechanical and Di2 electronic shifting options, allowing riders to tailor their mixed surface riding experiences. In addition to the crankset options, GRX includes front and rear derailleurs, disc brake calipers with an in-line brake lever option, and left and right STI hydraulic levers.
The series provides options ranging from gravel-tuned gearing ratios to custom ergonomics, dropper post integration and gravel-specific GRX wheels with wider rim profiles.
The GRX cranksets are built for tackling different riding terrains and riding styles, all coming with a +2.5mm chainline for increased tyre and frame clearance. GRX single ring cranksets offer the simplicity of shifting only on the rear cassette (options include RX800/600 40T chainrings or the RX800 42T chainrings) and are delivered with Shimano’s Dynamic Chain Engagement tooth profile on the front chainring to offer increased chain retention over bumpy ground.
Meanwhile the GRX double chainring RX810 crankset employs a 17-tooth gap which, at 48-31T, is the company’s widest-ever gear ratio. Together with the additional RX600-11/10 46-30T options, the double cranksets give big enough gear ratios for tackling the steepest climbs and pinning the steepest descents.
GRX Front derailleurs:
Complementing the cranksets, the Di2 or Mechanical front derailleurs are built with 2.5mm more outbound clearance for wider tyres to cope with riding on rough roads. Both RX800-series mechanical and Di2 front derailleurs are built to accommodate Shimano’s widest 17T front chainring 48-31T gear ratio whilst the FD-RX400 10-speed derailleur accommodates the 16T chainrings found on the RX600 46-30T 10-speed cranksets.
GRX Rear derailleurs:
Adopting the technology introduced in 2018’s RX rear derailleur, the GRX Di2 RDs or mechanical RDs are designed for silent, smooth and reliable shifting on rough terrain with a chain stabilising system known as SHADOW RD+ to manage ‘chain chatter’ and minimise unnecessary derailleur arm movement. GRX comes with the choice of four derailleurs depending on which cassette and gear shifting operation you choose.
GRX STI levers:
Gravel-specific ergonomic levers feature curved brake lever profiles and an anti-slip textured finish which can be gripped with assurance over rough terrain. The ST-RX815 also features an 18mm higher axis point.
To integrate the use of dropper posts in gravel riding, SHIMANO created the GRX mechanical ST-RX810-LA left hydraulic disc brake lever that, when used with a 1×11 drivetrain, can control a dropper post whilst also keeping the cockpit tidy. The integrated cable pulling system has a 9mm lever throw to operate dropper posts with cable heads at the shift lever. SHIMANO GRX also includes 1×11-specific RX800 and RX600-series left side hydraulic disc brake levers with no dropper or shift internals, including the 1×11 Di2 left-hand lever, which comes with three buttons for operating ancillary functions such as lights or third party computers.
GRX Braking systems:
At the top tier of the GRX family, one variant of the RX800-series brake levers (ST-RX815) offers Servo Wave technology coming from Shimano’s MTB brakes. This provides a stronger braking feeling with greater modulation options for more aggressive riding.
An additional braking option comes with an inline hydraulic sub-brake lever which connects to the main hydraulic line running to the front and/or the rear caliper. The sub-brake lever is designed to be mounted on the handlebar next to the stem offering options for braking when riding with hands on the tops.
The GRX calipers (BR-RX810/400) echo the design of Shimano’s flatmount road calipers to deliver powerful brake performance, taking features like one-way bleeding and ICE TECHNOLOGIES heat-dissipating finned brake pads and rotors to offer efficient cooling and long-lasting brake performance.
To complete the experience, Shimano has also created two gravel/adventure-inspired 12mm E-THRU axle wheel sets. The 700c or 650b tubeless-ready wheelsets offer an optimal balance between weight, stiffness and gravel durability, bringing a wider 21.6mm inner rim width and an off-set rim height of 22mm.