We all knew it was a matter of time before the GRX 12-speed mechanical groupset would electrify into the GRX Di2 12-speed. Now that first-ever electronic gravel-specific group gets its first refresh. Shimano has the chance to walk back a few features and add new ones, responding to customer and pro athlete feedback.
The groupset gets updated across the board, boosting efficiency, shifting speed, and ergonomics. The new electronic gravel groupset also incorporates some of the outstanding features of the Dura-Ace and Ultergra 12-speed Di2 component sets.
Plus – the new groupset is the first of Shimano’s 12-speed offerings (on the electric road side) to offer chain retention and management.
Shimano GRX Di2 12-Speed – What is it?
Shimano’s new 2 x 12-speed GRX (RX825) Di2 components are the brand’s new top-tier gravel groupset. The addition of 12-speed offers more integration with the company’s road offerings while optimizing gear options for gravel action.
The new GRX Di2 platform isn’t totally redesigned; it’s more refined. It’s hard to spot a ton of difference in a super quick look at the levers alone. However, small bits stick out once you take a closer look, and the rear derailleur looks very similar to the 12-speed mechanical version.
Riders now get a wireless cockpit, like the road Di2 groupsets in the Shimano road line. The shifting speed is faster compared to the previous version, with more refined gravel-specific gearing and ratios. We’ll get more detailed in the component breakdown section.
The new Di2 GRX group is cross-compatible with other Shimano 12-speed components. Riders can tailor their gearing with the 48/31-tooth chainrings or use the RX610 crank and its 46/30-tooth chainrings for more climb-ability.
The same goes for cassettes, with 11-36T or 11-34T option. Riders can use cassettes for a wide range of gear with tight gear steps to spin a comfortable cadence.
GRX RX825 Component Break Down
Shimano GRX Di2 12-Speed Shift/Brake Levers
Shimano’s 12-speed GRX Di2 features a wireless gravel-specific cockpit.
What is a “gravel cockpit” you ask? Think of the shape of most modern gravel handlebars and the trademark flare. Thanks to its round shape, the updated GRX lever body pairs nicely with flared bars. This new shape helps make the transfer from the handlebar to the hood smoother and creates a larger surface area to help eliminate pressure points. It’s very noticeable when you go from the older to the newer GRX Di2 version. The shape is slightly larger, concentrating on ergonomics, comfort, and palm support.
The hoods have the trademark texture and anti-slip brake surface you either loved or hated from the previous GRX Di2 groupset, but with a sculpted look and less blocky shape. Instead of the thick, large “bars” running down the shifter’s side, the new grip cover adopts a thinner version with an updated additional grip.
Easy to Access Thumb Button
The new GRX Di2 levers still use a third Di2 button on the inside of the hood. Now, it is more pronounced and accessible. The thin and near flush button on the 11-speed version could disappear when using winter gloves, but the new pronounced version is easy to push with your thumb, no matter where your hands are on the shifter.
The shift buttons on the lever blade are nearly identical to the first iteration, but trade “dots” for “lines” on the shift paddle. Like the previous version, the “downshift” paddles are smooth without texture.
Wider Lever
The brake lever is slightly wider and uses a more exaggerated shape than the 11-speed lever. From the pivot point, the lever blade flares outward faster than on the 11-speed Di2 version. This allows for better one-finger brake placement (IMO) and finger ergonomics.
The levers operate on replaceable coin-cell batteries (2 x CR1632), which Shimano expects to last 3.5 to four years.
If you’re interested in sprint or auxiliary shifter pods, you can easily add them to the new system (more on that later)
How About the Brakes?
The brakes are functionally identical to the updated 12-speed Shimano groupsets. That means more pad and debris clearance, better performance, and an effortless bleed operation. The caliper body looks like the updated Dura-Ace and Ultegra versions, with similar (excellent) performance.
Key Features – Shimano ST-RX825
- 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 an expected lifespan of 3.5 to 4 years
- Weight: 415 grams/pair
Hitting Shift Switches
The new GRX Di2 system allows for easy addition of auxiliary shift buttons.
The buttons don’t need to be assigned a “shift,” either. The rider can program them for whatever they’d like. That means you can have the switch buttons control compatible lights and computers or act as a lap button during workouts. These buttons could also be exciting on e-bikes, offering compatible options for TQ motor control.
How do they install? It’s as easy as plugging in one of Shimano’s satellite shifters, whether on the tops, drops, or aero bars, program, and roll.
Those interested in the TT setup note the 11-speed Tri cockpit setup is compatible with the 12-speed. Why all the button and auxiliary shift options? Since some gravel races and FKT pursuits involve a dialed aero-like position, having easy-to-access buttons can keep riders comfortable and maintain their effort without moving their hands.
Shimano GRX- 12-Speed Shadow RD+ Rear Derailleur
The RX825 rear derailleur features Shimano’s RD+ technology, which is also found on the 12-mechanical GRX. It boasts an easy-to-access on/off switch for engaging the clutch.
Like on Shimano’s road 12-speed Di2 systems, the rear derailleur is also the drivetrain’s communication hub. It communicates wirelessly with the shift levers, compatible computers, and the e-tube project via smartphone.
Also like others in the Shimano Di2 12-speed setup, the rear derailleur houses the system’s charge port and the multi-function button. The button lets riders quickly check battery level, pair via Bluetooth, and enter adjustment mode for both derailleurs.
Key Features Shimano RD-RX825 Rear Derailleur
- Chain Stabilization
- Integrated D-FLY connectivity and charging
- 12-speed compatible with 11-34T and 11-36T cassettes
- Weight: 310 grams
Wider Chain Line Means More Clearance
The RX825 system employs a +2.5mm chain line for improved tire clearance. This is especially helpful with the trend towards wider tires and events where mud is a deciding factor between riding or walking.
Key Features GRX Di2 FD-RX825 Front Derailleur
- Chain line +2.5mm vs. conventional road
- Wider tire clearance
- 2 x 12-speed
- Weight: 142 grams
How about the crankset?
The crankset is relatively unchanged from the 11-speed version. The rings are updated to be 12-speed compatible and boast a sleeker and lighter look with some unique cutouts.
Side by side, it is hard to tell the difference without the rings.
Shimano GRX Di2 RX825 Pricing
The Shimano GRX Di2 12-speed pricing is $2,533.00 for the full groupset. That’s the same price (give or take $50) as the 11-speed GRX groupset. Suppose you’re thinking of making the jump from mechanical to electronic 12-speed – the Di2 version of GRX 12-speed is $950 more than its mechanical counterpart.
Shimano GRX Di2 12-Speed Availability
The new Shimano GRX RX825 groupset is available for sale now. Shimano coordinated with supplies and shops to ensure the groupset was ready to roll as soon as possible.
New GRX RX880 Gravel Wheelset
Along with the new GRX Di2 group set, Shimano launched a new, more comprehensive, lighter set of carbon gravel wheels.
The new wheelset boasts a 25-millimeter internal width and an updated direct engagement free hub. The set weighs 1394g and retails for $1,550. Look for a stand-alone review on these coming shortly
Announcing E-tube Project Customization and Front Shift Next
Using Shimano’s E-Tube Project rider phone app, riders can choose between different gear shift intervals for multi-shift. They can also customize shift button assignments to determine which buttons perform which functions. It has different automatic shift modes, such as synchronized or semi-synchronized, and fine-tuned shifting details.
The launch of RX825 dovetails with the debut of Shimano’s new Front Shift Next functionality.
With this firmware update, riders can now utilize Shimano’s E-Tube Project app to program any 12-speed Di2 button to shift the front derailleur. This new firmware is compatible with Shimano’s family of 12-speed road Di2 groups.
Why Front Shift Next? To free up more space with switches and use them for other gear on the bike. Shimano feels the “result is simpler, more intuitive shifting for less-experienced riders and quicker decision-making for veteran riders in the heat of competition.”
Look for a full review, and a head-to-head comparison with weights coming shortly.
