Everything You Need to Know About the Latest Shimano GRX 12-Speed Gravel Group
In this Article
At the end of summer 2023, the Japanese manufacturer Shimano, leader in the cycle components market, unveiled its latest gravel-specific groupset: the GRX 12-speed. Already adopted in road ranges since 2021, the 12-speed technology finally makes its appearance in the gravel range. Available since May in electronic version, this new groupset is presented as the ideal companion for gravel enthusiasts looking for more performance and versatility.
Shimano GRX: a complete range designed for gravel
Introduced in 2019, Shimano's GRX range is specifically designed for gravel, just like SRAM's XPLR range and Campagnolo's Ekar. Shimano GRX offers ergonomics and gear ratios suited not only for gravel, but also for bikepacking and cyclocross. The GRX range includes:
- Derailleurs
- Cranksets
- Shifters
- Brakes
- Wheels
Shimano ensures the compatibility of GRX products with existing road (Tiagra, 105, Ultegra) and MTB (Deore, SLX, Deore XT) cassettes, chains, and discs in 10 or 11 speeds, and XTR for 12-speed. If you're hesitating between a gravel bike and a road bike, check out our complete article on the subject.
A range divided into three main families
The entry-level GRX is only available in mechanical version. The Shimano GRX 10-speed group is offered in double chainring version (46-30T) and cassette 11-42T or 11-36T.
Available in mechanical version in double chainring (48-31T) or single chainring (40 or 42T), the GRX 11-speed also comes in an electronic Di2 version (only in double chainring) compatible with cassettes 11-40T, 11-42T, and 11-46T.
3. The GRX 12-speed: (GRX 820 and GRX 825)
The latest addition to the GRX range is available in double chainring (46-30T or 48-31T) in mechanical or electronic version (only in 48-31T) compatible with cassettes (11-34T or 11-36T). The groupset is also available in single chainring (40 or 42T) compatible with cassettes 10-45T and 10-51T previously found only on MTB.
Technologies and technical improvements for the GRX
The Shimano GRX groupsets incorporate advanced technologies, some of which are already present in MTB and road ranges, to offer the best possible experience to gravel enthusiasts.
The DYNAMIC CHAIN ENGAGEMENT
Featured on the single chainrings of the GRX range, Shimano's DYNAMIC CHAIN ENGAGEMENT+ is a chainring tooth profile specially developed for cross-country (XC), enduro, and trail riding, now available for gravel. The particular tooth profile ensures better chain retention on rough terrain and helps reduce chain abrasion and wear over time.
The Shimano Shadow RD+
Featured on GRX derailleurs, the Shadow RD+ helps maintain tension in the derailleur cage. It promotes more precise and silent shifting and prevents chain jumps on technical terrain.
The Servo Wave
Integrated into classic GRX brake levers as well as BL-RX812-R levers used alongside shifters, similar to what is seen in cyclocross, the Servo Wave technology provides more power and precision in braking thanks to faster pad contact and a better progressive effect at the end of the lever stroke.
Ice Technologies Freeza
The new GRX discs feature Ice Technology Freeza, which helps reduce heat buildup through a 3-layer disc design (an aluminum layer sandwiched between stainless steel layers) with fins for better heat dissipation, maintaining full braking power.
Raised lever axles
The GRX brake lever axles have been raised by 18mm compared to traditional road levers to increase leverage and provide more effective braking when keeping hands on the shifters.
It is not always easy to choose between a single chainring and a double chainring. Shimano has therefore chosen to offer three versions for its new 12-speed groupset to meet all uses.
Shimano GRX 1×12
In its single chainring version of 40 or 42 teeth, the Shimano GRX 12-speed is offered in two versions starting at 1,590 euros.
- With a 10-45 cassette
In this configuration, the rear derailleur has a medium cage incorporating the Shadow RD+ technology mentioned earlier. This configuration is ideal for competitors and more sporty riders. With an extra gear, the GRX 12-speed offers perfectly controlled cassette spacing.
- With a 10-51 cassette
This is the big news of this groupset: the compatibility of an XXL format cassette previously seen on MTB with Microspline technology. These new freehub bodies with more widely spaced splines help limit damage to the gears. Shimano has developed a derailleur capable of receiving a 10-51 cassette for the most adventurous, also incorporating Shadow RD+ technology. The spacing is less well handled than its 10-45 counterpart, but this configuration allows for adventure and overcoming any challenge.
Shimano GRX 2×12
In its double chainring version of 46-30 (RX 620) and 48-31 teeth, Shimano offers two cassettes in 11-34 or 11-36 teeth. A configuration that, according to Shimano, "harmonizes perfectly with most existing 700c wheels thanks to its use of the HG freehub body". This option is the most suitable for those looking for versatility. The double chainring versions of the GRX 12-speed are offered starting at 1,630 euros in mechanical version and since May 2024 in electronic version starting at 2,329 euros.
The new features to remember
More compatibility
To allow the greatest number to enjoy these new features without breaking the bank, Shimano offers the GRX 12-speed in RX600 version with levers and cranksets compatible with RX820 and RX825 models. More affordable, these products retain the advantages of the 12-speed without compromising quality. The shifters feature the GRX Hood non-slip coating found in the RX820 range. The RX610 crankset (1×12) offers the same crank length options as the RX820 and is available with new 38-tooth (new) and 40-tooth steel chainrings.
More compact brake calipers
More compact than the previous version, the new GRX 12-speed calipers incorporate a new bleed system (identical to the latest Dura-Ace and Ultegra), and greater spacing between pads and discs. These evolutions have been designed to limit disc rubbing noise after heavy braking or after passing through difficult environments such as sand or mud.
A revised front derailleur and shifters
Compared to the old 11-speed version, the new 12-speed front derailleur has been offset by 2.5mm to provide more clearance, allowing the use of wider tire sections and easier mud evacuation. As for the shifters, they have been redesigned and are now more curved for better integration with flared handlebars. A reminder, flare is the angle between the vertical of the handlebar and the side of the handlebar. The larger it is, the better the stability. This feature is found on many handlebars dedicated to gravel riding.
The new GRX Di2 2 x 12-speed
This is the novelty of this year! We were worried last year when Shimano announced the arrival of its new GRX groupset about seeing the end of the Di2 electronic transmission as was the case with MTB ranges. We have been reassured since May with the arrival of a double chainring Di2 version.
The integration of the electronic transmission presents several advantages, including having a cleaner cockpit with fewer cables, smoother shifting, and derailleurs that are less likely to go out of adjustment. It also has some drawbacks such as reliance on batteries and therefore a limited usage range (around 1,000 kilometers), which for those who want to go bikepacking or practice ultra-cycling can be a limiting factor.
Still extensive compatibility
As with the mechanical RX820 versions, you have the choice between a double chainring crankset of 48-31 teeth or a 46-30 teeth version with the RX620 crankset. Similarly, you can choose between an 11-36 or 11-34 teeth cassette for a wide range of gear spacing options.
Here is a summary of the tooth options compatible with the GRX RX825 Di2:
- 48/31 teeth, RX820 crankset
- 46/30 teeth, RX610 crankset
- 11-36 teeth, HG710 cassette
- 11-34 teeth, R9200, R8100, R7100 cassettes
More customization of Di2 controls
This is one of the great advantages of electronic transmission: configuring the Di2 buttons to operate your various accessories. By pressing one of the satellite buttons on the shifters, whether on the top of the hood, in the curve of the handlebar, or from a button integrated into an aero handlebar, for example, you can change the display on your GPS or manage your lights without having to take your hands off the shifters. A real plus when you know how difficult it can be to let go of your handlebar on certain paths.
New, even more ergonomic levers
The new Shimano DUAL CONTROL levers benefit from a more curved shape, for better pressure distribution of the hand on the lever, especially with the use of flared handlebars. The lever hood has been raised to prevent hand slippage.
As with Shimano's 12-speed road Di2 transmissions, the rear derailleur is the brain of the transmission. It communicates wirelessly with the shifters, compatible GPS devices, and the E-TUBE PROJECT Cyclist app via a smartphone. It also houses the charging port and a multifunction button that allows you to easily check the battery level, pair via Bluetooth, and enter adjustment mode for both derailleurs. Through the Shimano E-TUBE PROJECT Cyclist app, you have the option to choose between different shifting intervals, customize button assignments (which buttons perform which functions), and program different shifting modes such as Synchronized and Semi-Synchronized modes.
FRONT SHIFT NEXT: A software update dedicated to competitors
The launch of this new groupset coincided with the launch of the FRONT SHIFT NEXT feature. To make shifting always more intuitive, you can now program any Di2 button to move the front derailleur to the chainring you are not using. A small update that will delight the most competitive.
Our opinion on the GRX 12-speed mechanical single chainring
After more than 2,500 kilometers with the latest GRX 12-speed in its single chainring version paired with a 10-51 cassette, I can say that this groupset is a real pleasure to ride. Regardless of the conditions, it has not failed in its mission to provide quality shifting.
I had the opportunity to test the limits of the groupset during The Traka in Spain. The 340 kilometers of gravel were extremely demanding on the equipment with an impressive amount of mud throughout the course due to heavy rains that hit the region a few days earlier. At no point did I have difficulty shifting despite the harsh conditions.
The shifting remains similar to what is found on an Ultegra, it's rather "smooth". However, be careful not to adjust the Shadow RD+ when the chain is at the top of the cassette, as it brings rigidity in the shifting once past the middle of the cassette. I recommend adjusting the Shadow in the middle of the cassette to limit resistance in the lever during shifting.
As for the braking, again, very little to complain about. During ford crossings with mud and water, the brakes easily evacuate small debris and effective braking is quickly restored.
The verdict
In conclusion, this new Shimano GRX 12-speed gravel groupset proves to be remarkably efficient. In its "adventurer" version with a 10-51 cassette, it is a true all-rounder and will allow for unlimited usage, provided you have the legs to take it up the steepest slopes. However, it can still be somewhat "noisy" depending on the gear used. With this groupset, Shimano reaffirms its status as the leader in transmission. Enough to make Sram blush?
More info on the Shimano GRX groupset: https://bike.shimano.com/en/home.html
