Shimano GRX is very now an established part of the gravel scene, last year saw the launch of the cable-connected 12-speed GRX, but we are now seeing the launch of the 12-speed Di2 version. The headline changes go beyond the addition of additional sprockets, the revised hood design to better mesh with flare bars, and the added button function as well as the ability to use satellite shifters. 

Like the Dura-Ace, Ultegra, and 105, the new GRX Di2 (Shimano-coded RX825) is semi-wireless, with wireless control on the hood, but with a hardwired connection between the battery and the front and rear derailers. We've been looking at patents for the fully wireless 13-speed Shimano group set recently, but it's clear, at least now, that this wasn't the new GRX.

For ease, the new components are divided into their constituent parts. 

At first glance, it would be hard to find the difference between the new hood in the 11-speed group set and the old Di2 hood. The 11-speed hood is universally popular in our experience, and Shimano seems to see little point in overhauling what people like. 

The same ribs are on the hood cover for improved grip on rough terrain and the "peduncle" still featured that feature and almost hooked the peak to it. But to create a smooth transition from the bar to the shifter and reduce the pressure point, the diameter will be larger.

The anti-slip coating of the lever also remains, and the lever is kinder than the load lever to make working with the flare bar better. The inner thumb button on the upper part of the pedicle peak, is still there to work as a satellite shifter or to control a computer screen. With the cable groupset, the hood is designed to be flat when mounted on a flared rod.

A new addition to the hood is the battery level indicator light on the top of the shifter handle at the front, so when you pick up the coin cell battery powering the shifter

The gearing is currently 2x12, but this group set shares the accessory crank set to the cable-operated 12sp GRX, the cable-operated It makes sense that the current 1x crankset offered for users is compatible with the Di2 version. However, this is not mentioned in the press materials.

The 12sp Di2 chain set is the same as the 12sp cable model and with the same 48/31 tooth set-up as the current 11sp offers, the smaller 46/30 new GRX 12sp cable operating GRX chainset itself is looking similar to the current 11spd model, but is machined from an outer chainring. There is more material to be done.

Cassette options are either 11-36t or 11-34t options, depending on whether customers want a wider range or narrower spacing. These are the same components found in the cable group set. 

The front derailer once again has striking similarities to its front legs. The chain line remains 2.5mm larger on the road for slightly improved clearance. The front panel of the main motor unit is not silver, but all black, and on the inner plate there is an additional cutout to shed a few grams.

Oddly, the rear derailleur seems to have added material. The outer plate of the central parallelogram is no longer machined, but now it is solid. The whole thing is all black, with a switch for the clutch to facilitate the removal of the wheel, with the same shadow setup as before. 

The lower cage twists heavily backwards in the middle of its length, has a larger cutout and appears to have a larger bottom jockey wheel, but again contains a larger cutout. The charging port also remains on the backside of the rear derailleur, consistent with the rest of the di2 family. 

The previous rear derailleur had a maximum capacity of 42t and is not listed, but it is not expected that this has changed. 

The brake is the same as the brake of the 12sp cable group set. This requires this over the current 11sp, as the GRX BB-R820 Caliper features Shimano's "Servo wave" brake technology, which spreads the pad wider and takes up more of the pad movement on the first lever stroke, reducing pad friction and improving modulation commonly seen when riding off-road.

This latest iteration of the GRX Di2 is compatible with satellite shifters, with either a bar or bar end for those gravel riders who use TT bars. But more than that, the buttons in this group set are now more programmable than ever.

Using Shimano's E-Tube app, riders can assign 1 button to shift the front derailleur in both directions and release the button for other functions such as computer screen control, lap function and compatible lights. The new GRX Di2 is identical to the Deore XT model of Shimano's MTB line, but also matches the GRX version of the PD-M8100 pedal with gravel-inspired graphics. 

The prices and weights for which information is provided are outlined below. We will update this as more information becomes available.