Shimano GRX Di2 front derailleur(Image credit: Shimano)
The additional handlebar top brake levers can be fitted as a pair or a single unit(Image credit: Shimano)
Component and drivetrain giant, Shimano have launched a versatile gravel/adventure-specific groupset, which can be set up as double or 1X, 10- or 11-speed, mechanical or electronic shifting, wide or close gear ratios and be integrated for use with a dropper post.
Shimano say the new GRX series is a platform that addresses riders’ needs now and into the future through gravel riding, modern adventure road riding, bike-packing or cyclo-cross.
The Shimano GRX range includes RX400, RX600 and RX800 components, which are compatible as a 1x11, 2x11 or 2x10 drivetrain setup, dropper post-integration, disc brakes and wider rimmed, gravel specific GRX wheels.
Shimano say the components are recommended to be used with existing Shimano MTB (Deore XT, SLX or Deore) or Shimano Road (Ultegra, 105, Tiagra) cassettes and chains.
Shimano GRX cranksets
The Shimano GRX cranksets are available in a 1X or 2X setup with Shimano saying a +2.5mm chainlink increases tyre and frame clearances.
Shimano’s 1X GRX crankset is available as a 40T or 42T chainring and utilizes Shimano’s Dynamic Chain Engagement toothing profile to offer increased chain retention on rougher surfaces.
The double chainring Shimano GRX crankset is available in a 48/31t option – the company’s widest ever ratio – alongside a 46/30t option.
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Shimano’s GRX front derailleurs move the chainline outbound by 2.5mm to improve clearances at the rear end of the bike, with Shimano claiming a tyre clearance of 42mm when used with a Shimano GRX front derailleur. However, this means when using a Shimano GRX front derailleur, a Shimano GRX crankset must also be used.
Shimano GRX RX800 series front derailleurs (mechanical and Di2) can accommodate the super-wide 48/31 chainrings while RX400 derailleurs can only accommodate the smaller 16-tooth gap.
The Shimano GRX rear derailleurs utilise technology first seen in last year’s Shimano Ultegra RX rear on/off clutch derailleur, which featured a chain stabilising system dubbed SHADOW RD+ by the brand. The technology essentially reduced chain slap when riding over rough surfaces and was used by Trek-Segafredo last season.
The Shimano GRX rear derailleur line-up features two Di2 options and three mechanical options, all featuring the same SHADOW RD+ seen on the Ultegra RX component.
Shimano RD-RX815 (Di2) and RD-RX810 rear derailleurs (short cage) can be used with Shimano Ultegra, 105 or Tiagra 11-30/34 cassettes, while RD-RX817 (Di2) and RD-RX812 rear derailleurs (long cage) can accommodate Shimano Deore XT, SLX or Deora 11-40/42 cassettes.
Shimano say all GRX rear derailleurs come with similar pull ratios to the brand’s road derailleurs.
Shimano’s GRX levers feature gravel-specific ergonomics, which, through 18mm higher axis point, a curved brake lever profile and an anti-slip textured finish, Shimano say offer extra grip and assurance over rough terrain.
When running ST-RX810-LA levers in a 1x11 drivetrain setup, the left lever can be configured to control a dropper post without the need for an additional lever or switch on the cockpit.
Shimano GRX STI shift/brake lever weights: ST-RX815-L/R (Di2): 565g (pair), ST-RX810-LA (dropper post left lever): not yet available, ST-RX600-L/R (mechanical): 611g (pair), ST-RX400-L/R (10-speed mechanical): 613g (pair) – all claimed.
Shimano GRX brakes
As you might expect, the Shimano GRX groupsets are hydraulic disc brake only, with Shimano saying their top tier (ST-RX815) unit features Servo Wave technology seen in the brand’s MTB brake systems.
The non-Servo Wave brakes in the GRX line-up have claimed stopping power similar to Shimano Ultegra, 105 or Tiagra disc brakes for RX810 (non-Servo Wave), RX600 and RX400 series, respectively.
An additional, inline brake lever is available to be fitted to the handlebar tops at the stem for an extra braking option while riding on the tops, a setup often seen in cycle-cross or the cobbled Classics.
Shimano GRX calipers use flat-mount standard and Shimano’s ICE braking technologies.
Shimano GRX wheelset
Alongside the Shimano GRX braking and drivetrain components, Shimano have also launched two gravel-specific wheelsets. The thru-axle wheelsets are available in 700c or 650b size, a 21.6mm inner rim width, rim height of 22mm and are tubeless ready.
Shimano GRX mechanical components are expected to be available in Europe from June and Di2 components in August. Availability in other territories, along with pricing was not available at time of writing.
