Background information
So smooth! The new GRX Di2 RX825 groupset by Shimano
by Patrick Bardelli
Shimano Gravel 1x12 becomes wireless
24.6.2025
Translation: machine translated
With the new 1x12-speed GRX Di2 components, Shimano is celebrating its debut in the fully wireless shifting segment for gravel bikes. The manufacturer has incorporated technology from the latest road and mountain bike groupsets.
After road and mountain bike comes gravel - completely logical. The new, wireless GRX RX827 rear derailleur utilises the wireless Cockpit that was introduced with the 2x12-speed road groupset from Shimano. And it features the fully wireless technology that was first used in the XTR rear derailleur of the M9200 series, according to the announcement.
The manufacturer writes: «This offers a completely wireless drivetrain that is designed for performance, durability and versatility. The RX827 rear derailleur completes the GRX range and provides a comprehensive range of mechanical and electronic shifting options in 1x12 and 2x12 gear configurations, allowing riders to customise their drivetrain to suit their gravel riding needs.»
Source: Shimano
Wireless GRX drivetrain
According to Shimano, the heart of the GRX 1x12-speed system is the RD-RX827 wireless rear derailleur, «which offers gravel riders unrivalled chain guidance and precise shifting.» (Only Shimano's copywriter knows what «unrivalled chain guidance» means) The new system has been developed for seamless performance on a variety of terrain, whether racing, on back roads or on all-day adventures.
The manufacturer combines the RD-RX827 wireless rear derailleur with the existing Di2 Dual Control Levers ST-RX825, the crankset FC-RX820, the brakes and the XT 10-51T cassette. The press release states: «This combination offers Shimano's characteristic Di2 performance in an elegant yet robust 1x12-speed package.»
Source: Shimano
The XT 10-51T cassette on the gravel bike sounds interesting and makes me want to try out the combination. It should be possible to ride steeper climbs than with a 10-44T cassette, for example. The existing 2x12-speed configuration was my first contact with an electronic groupset for gravel bikes a year ago. I have linked my impressions here:
Expanded Di2 button functions - versatile shifting options
New for GRX 1x12-speed is the hydraulic disc brake lever, which offers the same ergonomic features as the ST-RX825 Dual Control Levers. However, with raised grips, a ribbed surface and non-slip brake levers, Shimano has dispensed with electronic shift buttons to enable a 1x configuration.
The press release states: «Regardless of whether the new BL-RX825-L brake lever is used or a pair of GRX ST-RX825 Dual Control Levers, Shimano 1x12-speed GRX offers a variety of shifting options thanks to Di2's customisable buttons as well as additional accessory shifters.»
Source: Shimano
Our purchasing department is clarifying whether and when we will have the components of the new GRX-Di2 components for gravel bikes from Shimano in our range. If possible, we will then test the technology and report on it.
Header image: Shimano
Patrick Bardelli
Senior Editor
Patrick.Bardelli@digitecgalaxus.chFrom radio journalist to product tester and storyteller, jogger to gravel bike novice and fitness enthusiast with barbells and dumbbells. I'm excited to see where the journey'll take me next.
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