In one of the least surprising announcements of the gravel year, Shimano today has announced an electric version of its popular GRX groupset. If the big news of August 2023’s GRX announcement was that it had one extra gear (or two if you run a 2x setup) then this new GRX Di2’s big news is that it’s wireless!*
Before you get the press release, here’s our take on things:
* Actually, it’s only semi-wireless. GRX RX825 Di2 to give it its full name, follows the pattern first launched with Dura Ace road group in 2021, and the GRX groupset seems to have much in common with the Ultegra road shifters and mechs. This means that the shifters are truly wireless – they run off coin cell batteries that last for years. However, the front and rear mechs are still physically wired to a common battery, hidden in the frame or the seatpost. And yes, it’s only available in a 2×12 setup, and for conventional ’11 and up’ Hyperglide freehubs.
It’s not just a road groupset with a moustache and dangle bag, though. The chainline is shifted outboard by 2.5mm for better clearance with larger tyres and, like with mechanical GRX 820, you do get the extra security of a Shadow RD+ (switchable) clutch rear mech. In addition, the brake hoods are more rounded in anticipation of being run on more flared handlebars than a conventional road bar.
One question we were asking before we saw it was: “Could this be a glimpse into the technology we’ll see on the long overdue XTR groupset?” – Not very likely at all. For a start, where would the battery go? Current mountain bikes don’t have provision for either front mechs, or for internally-mounted batteries. And new GRX Di2 makes no mention of external (bottle cage or elsewhere)-mounted batteries, and seeing as dropper posts now fill up mountain bike seat tubes, there’s no room there either. So no, no, no. Which is good, as a semi-wired, semi-wireless mountain bike groupset would be a little lame.
While we’re quizzing the stonefaced Shimano PR guy, we couldn’t help but ask… ‘Hey, this only mentions a Di2 2x setup. What, no Di2 1x setup? 1x is two thirds of the current GRX mechanical range!’ – to which our steely-gazed PR guy could only nod. 2×11, and now 2×12, setups are the most popular GRX version that Shimano sells, and given that its European office is in the middle of the pro-road racing land of Netherlands, it’s no surprise that its currently focusing all of its efforts on the more racy end of the gravel world. However, in a half-mumbled exchange, we were told that 1×12 Di2 isn’t ruled out for some time in the future. Which is good, as XTR is going to have to be 1×12 wireless at the very least. (And BikeRadar has unearthed a wireless 13 speed Shimano patent application…)
And althought, the groupset will probably take a while to appear on shelves and on bikes on shop floors, we are certain that there’ll be plenty on show at the Unbound Gravel event at the end of May.
And, now, here is that press release in full!
SHIMANO Expands Gravel Lineup with New 2 x 12-Speed GRX Di2
Electrifying Shimano’s 12-speed gravel component family, the new 2 x 12-speed GRX RX825 Di2 components combine Shimano’s unrivaled electronic shifting with optimized gearing options for riding, racing, and all-day adventures. The new suite of electronic Di2 parts features dual control levers refined for comfort and control, a SHIMANO SHADOW RD+ equipped rear derailleur for better chain management, and a gravel-optimized front derailleur for precise shifting.
Designed for gravel riders who live to be in the moment, who venture down lonely, unknown dirt roads, who take on routes and races with unpredictable outcomes, Shimano GRX 12-speed Di2 delivers precise, reliable, distraction-free performance in all conditions.
• Evolved Di2 Platform – Redesigned Di2 system with fast, precise shifting and a wireless cockpit design for the ultimate performance and absolute reliability.
• Advanced Gravel Drivetrain – Optimized 12-speed gearing for unrivaled efficiency and Shimano’s proven HYPERGLIDE+ technology for seamless shifting, no matter the situation.
• Refined Interface and Ergonomics – The ultimate balance of comfort and grip, GRX offers unparalleled ergonomics, a cleaner cockpit design, and ultimate customization.
Electrified 2 x 12-Speed GRX Gearing Options
Shimano’s new suite of gravel components brings an electronic shifting option to the 2 x 12 GRX group that launched last year. Pairing the new GRX RX825 Di2 shift levers, available satellite switches, front derailleur, and rear derailleur with existing RX820 crankset, cassette, and brakes, riders will enjoy Shimano’s hallmark Di2 shifting performance and reliability with 2 x 12-speed gravel gearing.
Like with the RX820 mechanical components, riders can tailor their gearing with the 48/31-tooth chainrings or opt to use the RX610 crank and its 46/30-tooth chainrings. Similarly, riders can choose from an 11-36T or 11-34T cassette for a wide gear range with tight gear steps so they can spin a comfortable cadence.
Update on smaller gears:
UPDATE: Shimano has just told us that the RX610 46/30 crank isn’t compatible with new RX825 – you would think they’d check these things beforehand, eh? So actually, new Di2 RX825 will only work with the bigger/racier 48/31T chainset
GRX RX825 Di2 compatible gearing options:
• 48/31T RX820 crank• 46/30T RX610 crank //Update – not actually compatible, as previously stated.//
• 11-36T HG710 cassette
• 11-34T R9200, R8100, R7100 cassettes
Any of these gearing combinations pairs with Shimano’s latest carbon gravel wheels, the WH-RX880. With 25-millimeter internal width and updated DIRECT ENGAGEMENT freehub, the RX880 wheels provide a vital connection between rider and road, however remote or rugged.
Unrivaled Shimano Di2 Electronic Shifting for Gravel
Like its 12-speed DURA-ACE, ULTEGRA, and SHIMANO 105 Di2 siblings, the new GRX Di2 system is wired where it makes sense, featuring a central, multi-port battery that supplies stable, long-lasting power to both front and rear derailleurs. Smaller diameter wires connect directly from the battery to each derailleur, eliminating the need for junctions and streamlining the build process. The central internal battery also simplifies charging and remains secure over the roughest roads, trails, or whatever less traveled path a rider may choose.
Shimano Di2 Wireless Cockpit
Shimano’s 12-speed GRX Di2 features a wireless gravel-specific cockpit where raised hoods with ribbed surface texture and anti-slip brake levers provide ultimate hand security no matter how spicy the ride gets. That secure hand position is enhanced, as it was with the original GRX RX815 Di2 DUAL CONTROL LEVERS, with the location of the third Di2 button on the inside of the hood. Whether used as another shift location or for scrolling through screens on a cycle computer, this third button is another way to fully experience Shimano’s electronic Di2 system.
Flared For Gravel
The new dual control levers also employ a gravel-optimized body shape cross-section for seamless integration with flared handlebars. Rounder in shape, the transfer from handlebar to hood is smoother and creates a larger surface area to help eliminate pressure points.
ST-RX825 – Hydraulic Disc Brake DUAL CONTROL Lever
• Wireless Di2 Connectivity
• 2 x 12-speed Dual-Control Lever
• Gravel-specific brake lever and bracket ergonomics
• New flared drop bar optimization
• Anti-slip coating on brake lever surface
• Three Di2 buttons per lever for E-TUBE PROJECT Cyclist app customization
• Replaceable coin cell batteries (2 x CR1632) with expected lifespan of 3.5 to 4 years
• Weight: 415 grams / pair
Accessory Di2 Shift Switches
The new Di2 system also allows for accessory shift buttons, another key advantage of electronic shifting. Plugging in one of Shimano’s satellite shifters, whether on the tops, drops, or on aero bars, riders can more consistently maintain their effort without the need to move their hands. Like the third button on the GRX Di2 dual-control levers, these satellite switches can be assigned various functions including shifting of either derailleur, to control compatible lights and cycle computers, or as a lap button during workouts.
SHIMANO SHADOW RD+ Rear Derailleur
The RX825 rear derailleur features Shimano’s pioneering SHADOW RD+ technology. With its convenient on/off switch, SHADOW RD+ makes removing the rear wheel easy when turned off. When on, the drivetrain is under additional tension that makes for a quieter ride and more precise shifting.
Like on Shimano’s road 12-speed Di2 systems, the rear derailleur is also the communication hub of the drivetrain, communicating wirelessly with the shift levers, compatible cycle computers, and E-TUBE PROJECT Cyclist via a smartphone. It also houses the system’s charge port and the multi-function button which allows riders to easily check battery level, pair via Bluetooth, and enter adjustment mode for both derailleurs.
RD-RX825 Rear Derailleur
• SHIMANO SHADOW RD+ Chain Stabilization
• Integrated D-FLY connectivity and charging
• 12-speed
• Compatible with 11-34T and 11-36T cassettes
• Weight: 310 grams
Wider Chainline for More Clearance
Like the very first GRX groups, the RX825 system employs a wider, +2.5mm chainline for improved tire clearance. This is especially helpful with the trend towards wider tyres and events where mud is expected.
FD-RX825 Front Derailleur
• Chainline +2.5mm vs. conventional road FD
• Wider tire clearance
• 2 x 12-speed
• Weight: 142 grams
E-TUBE PROJECT Customization and FRONT SHIFT NEXT
Using Shimano’s E-TUBE PROJECT Cyclist application, riders can choose between different gear shift intervals for multi-shift, customise shift button assignment (what buttons perform which functions), program different automatic shift modes like Synchronized and Semi-Synchronized shifts, and fine-tune shifting.
The launch of RX825 also coincides with the debut of Shimano’s new FRONT SHIFT NEXT functionality. With this firmware update, you can now utilize Shimano’s user-friendly E-TUBE PROJECT Cyclist app to program any 12-speed Di2 button to shift the front derailleur to whichever chainring you are not currently using and then toggle back and forth using the same button. This new firmware is compatible not only with GRX RX825, but also with Shimano’s family of 12-speed road Di2 groups. The result is simpler, more intuitive shifting for less-experienced riders and quicker decision-making for veteran riders in the heat of competition.
Along with dramatically simplifying the gear-changing process, Shimano FRONT SHIFT NEXT can also free up other switches to handle tasks such as moving through multiple screens on a paired cycle computer, turning on and off compatible lights, or hitting the “lap” button on your cycle computer so you can keep your hands securely in place, even during your hardest efforts.
And so that is new GRX Di2.
We’re on the list to get a play on the new groupset and we’ll report back when we have. So far we’ve only had the briefest of hands-on. (Incidentally… we were very impressed with the sheer lack of plastic packaging when we got to see the real things in the office…) – Stay tuned!
The wireless shifters run off coin cell batteries, which are said to last several years…
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