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New Shimano GRX Di2 12-Speed Group Refines Gravel Performance

Shimano GRX di2 12-speed crankset
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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.

Shimano GRX di2 12-speed lever buttons
All Photos: Jordan Villella/BikeRumor

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 full groupset

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. 

Shimano GRX di2 12-speed lever full side

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. 

Shimano GRX di2 12-speed lever side

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. 

Shimano GRX di2 12-speed front hoods

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. UPDATED: The FD-RX825 is not compatible with 46/30T FC-RX610.

Shimano GRX di2 12-speed cassette

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.

Shimano GRX di2 12-speed full bike shot

GRX RX825 Component Break Down 

Shimano GRX di2 12-speed lever

Shimano GRX Di2 12-Speed Shift/Brake Levers 

Shimano’s 12-speed GRX Di2 features a wireless gravel-specific cockpit.

Shimano GRX di2 12-speed lever shape

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. 

Shimano GRX di2 12-speed bar lever interaction

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. 

Shimano GRX di2 12-speed button thumb

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. 

Shimano GRX di2 12-speed blade buttons

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. 

Shimano GRX di2 12-speed levers

The levers operate on replaceable coin-cell batteries (2 x CR1632), which Shimano expects to last 3.5 to four years.

Shimano GRX di2 12-speed button

If you’re interested in sprint or auxiliary shifter pods, you can easily add them to the new system (more on that later) 

Shimano GRX di2 12-speed brakeset

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. 

Shimano GRX di2 12-speed lever buttons

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 di2 12-speed close up rear

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. 

Shimano GRX di2 12-speed cassette

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
Shimano GRX di2 12-speed cassette rear full

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. 

Shimano GRX di2 12-speed front derai l

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
Shimano GRX di2 12-speed crankset

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 12-speed full bike shot

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.

Shimano GRX di2 12-speed full bike

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. 

Shimano GRX di2 12-speed hub wheel

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

Shimano GRX di2 12-speed lever top

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.

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23 Comments
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TheStansMonster
TheStansMonster
1 month ago

Any changes to max total teeth? Can we still run a 50t or 52t big ring with both cassettes?

Evan
Evan
1 month ago

Weight difference on the shifters is huge, 150g lighter than grx di2 11s. I put the 11s di2 shifters on my road bike for the large-hand ergonomics despite the 200g weight penalty to ultegra. It’s good to see that now the gap is closed to almost nothing (12s ultegra shifters got heavier while these got lighter).

Tom Wenzel
1 month ago

“Tonight I’d like to party like it’s 1999!” – Shimano Industrial Design Group’s favorite song

Jan Hammer
Jan Hammer
29 days ago
Reply to  Tom Wenzel

If only new stuff from any of the 3 component brands looked as good as Shimano and Campy road kit did in 1999. This stuff might work well but aesthetically it’s lost.

Gary P
Gary P
1 month ago

Is it cross-compatible with Ultegra/Dura-Ace 12 speed Di2? As a flat lander, I’d like to run the GRX front derailleur and crankset with a tighter 11-30 “road” cassette.

Grillis
Grillis
1 month ago
Reply to  Gary P

Yes.

Andreas
Andreas
1 month ago
Reply to  Gary P

different chainline (2,5mm delta)

Dinger
27 days ago
Reply to  Andreas

“different chainline (2,5mm delta)”

As long as you match the F/D to the crank you should be ok.

Dane Morrison
Dane Morrison
1 month ago
Reply to  Gary P

Wider Q factor with that set-up is about the only downside. It should work no problem with Chorus 48/32 cranks or something like Praxis, assuming you want GRX for lower ratio than 105/Ultegra – then use 105 Di2 Front derailleur.

Chris
Chris
1 month ago

Can you use 12 speed Di2 Ultegra shifters/brakes with this grx group?

Laxonthree
Laxonthree
1 month ago

Yay 2x!!!

MagnanimousWaffle
MagnanimousWaffle
1 month ago
Reply to  Laxonthree

LOL, I had the opposite reaction — No 1x!?!?!

Al Minkman
Al Minkman
1 month ago

No 1 X 12? Really!?

Mike
Mike
1 month ago

These shifters look horrible, just like their first hydraulic RS505…

Marc Smith
Marc Smith
1 month ago
Reply to  Mike

try SRAM for a year and watch your hands die of pain…

Mike
Mike
30 days ago
Reply to  Marc Smith

Don’t know about new ones, but I have Apex 1 mechanical in my gravel bike and it’s fine. I actually really like the 1 paddle shifting – very intuitive.

Eggs Benedict
Eggs Benedict
1 month ago

It would be nice if Shimano, Sram and Campy had a standardized way to measure the length of the shifter hoods/bodies and how much more or less it changes the length of the reach when riding on the hoods.

packfill
packfill
1 month ago

I see they’re getting ahead of the market swing with the bringing back the 2x configuration. 🙂 Leave it to Shimano to try to tell everyone what they want. They fumbled away the mountain bike market a couple decades ago with their dual control stuff too.

Jan Hammer
Jan Hammer
29 days ago
Reply to  packfill

2x is at least as important for drop bar bikes that cross over a wide range of use and terrain. The main aim of 1x is chain retention for MTBs and there’s way less need for that on a gravel bike, plus many of us will spend a fair bit of time at the extremes of gear and also want smaller gaps than 1x has. YMMV.

threeringcircus
threeringcircus
27 days ago
Reply to  Jan Hammer

Agree with @Jan. However, I still don’t get the 16 & 17 tooth differences with ring combos on GRX cranksets, or the upside of stuffing 11 or 12 cogs into the span of 11-34 or 11-36 ranges for gravel riding.

Dinger
27 days ago

“stuffing 11 or 12 cogs into the span of 11-34 or 11-36 ranges for gravel riding.”

Tighter gear spacing. With a wide range 1x I feel like I’m almost always in the wrong gear for a give speed.

Gavin
Gavin
23 days ago

Baffling why they haven’t enabled a 10-45 1x setup using the MTB cassettes they make already. Otherwise it’s a nice upgrade.

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