In Europe the GRX RX825 Di2 groupset recommended retail price is € 2479. The mechanical (non-Di2) 12-speed GRX groupset costs € 1600.

For comparison, the recommended retail price for 105 Di2 is € 1800, and Ultegra R8170`s RRP was € 2449 at launch.

Complete bikes are usually sold for less than the sum of their parts, but the recommended pricing does give a good indication of where this newest GRX groupset sits compared to other Di2 groupsets.

Yep, you read that right. The new Di2 version of 12-speed GRX is 2x only. Shimano has not relased a dedicated 1x derailleur yet.

I'm sure it'll follow at some point though, possibly at the same time as a new XT or XTR Di2 groupset.

Personally I would've preferred a wide-range 1x12 GRX Di2 rear derailleur over 2x12. A front derailleur is nice for high-speed road type gravel, but for me, gravel riding is all about exploring and keeping things simple - and I love 1x12 for that.

Sure, you can still use RD-RX825 without a front derailleur if you want to, and the bike will shift just fine. In fact, my 105 Di2 commuter bike doesn't have a front derailleur installed either. Just the 105 rear derailleur and an AluGear narrow-wide chain ring.

It's not the same as having a proper wide-range derailleur though..

Either way, it's just a matter of time until Shimano embrace 1x12 with GRX Di2. We'll just have to wait a while longer.

Sticking with the proven and durable front derailleur design from previous generations, the FD-RX825 front derailleur is essentially the same as the R7150 105 front derailleur. It's not aero like the Dura-Ace and Ultegra front derailleurs, but it is more suited to handle the gravel chain line and is slightly more sturdy than its road siblings.

FD-R7150 similarities
This front derailleur so similar to the 105 front derailleur, it has a (top) limit bolt, an electric low limit, and a support screw. Also, it is optimised for a 47 mm chain line, just like Shimano's other GRX front derailleurs.

FD-RX825 weighs 142g, exactly the same as FD-R7150.

Just like the other 12-speed Di2 front derailleurs, the GRX RX825 rear derailleur houses the charge port, the function button, and a status LED.

Since this is a gravel rear derailleur, it also has a clutch that you can switch on and off.

Naturally, the derailleurs support Synchronized Shift, which will either shift the front derailleur automatically when the rear derailleur reaches a certain gear, or compensate for front derailleur shifts by automatically shifting the rear derailleur up/down a gear or two.

Manual mode is still the default, and using that is perfectly acceptable too. In fact, all of my bikes are set to manual mode most of the time.

RD-RX825 weighs 310g, slightly heaver than the RD-R7150 at 302g RD-R7150 and the 262g for RD-R8150. Keep in mind though that the GRX derailleur features a clutch mechanism, while the others do not.

While these 12-speed GRX shifters look similar to previous gravel shifters, there are quite a few subtle changes - besides the battery status LED of course.

The shift lever's bracket has been changed to better suit flared handlebars, and overall the new shifters are ever so slightly larger. This results into more shifter surface area to hold onto, less pressure points, and a slightly raised ridge (+ 3mm).

Shimano has also tweaked the buttons themselves. Both shift buttons are a couple of mm larger than before and there is an increased offset between the buttons and shift lever, meaning that the buttons are raised slightly - your fingers should be able to easily find the buttons.

Each shift lever has one E-Tube port (SD300), and one satellite shifter port. This means that you can run the system wired if you want to, and you can also install 12-speed satellite shifters.

Twelve-speed GRX Di2 shifters also have the side button, just like the 11-speed GRX shifters.

Just like the 105 road shifters, there are two CR1632 batteries in each ST-RX825 shifter. They'll need to be replaced after about four years.

A pair of ST-RX825 weighs 415g, compared to 423g for ST-R7170, 391g for ST-R8170 and 350g for ST-R9270.

Cassettes & Chainrings

With GRX 2x12-speed Di2 you can use any of the 12-speed road cassettes, the Dura-Ace and Ultegra 11 - 30T and 11 - 34T, as well as the 105 11-34 and the CS-HG710 11-36.

There are no GRX-specific cassettes. Even the mechanical 1x12 GRX groupset uses micro-spline MTB cassettes. This makes sense from a manufacturing point of view, but it can be a bit confusing to end-users.

You can use any 12-speed Shimano-compatible chain with 12-speed GRX.

The 2x12 GRX crankset comes with 48T - 31T chain rings, and comes in three crank arm lengths: 170mm, 172.5mm, and 175mm. The Q-factor is 151mm and it weighs 710g.

Do you like the way those new GRX shifters look? Prefer the side button over the Ultegra/Dura-Ace hood button?

As before with GRX, this groupset is part of the road category, and as such, is fully compatible with other 12-speed road groupsets.

Want to use the GRX shifters with your road bike? Go right ahead!

Prefer a clutch rear derailleur on your 1x12 105 bike? Sure, just install the GRX RD-RX825 rear derailleur.

You still need a battery, one or two derailleurs, shifters and other small parts. I've spent a bit of time getting all the component pages online for all of the new components.

General Components

• BT-DN300 Internal Battery (53g)
• EW-SD300 Electric Wire (12g)
• EW-EC300 Charging Cable
• EW-JC302 Inline 2-port Junction
• EW-JC304 Internal Junction B
• EW-AD305 SD50 to SD300 adapter