Whether we like it or not, electronic shifting has taken over the bike world. Some would stray as far as to say that it is the new gold standard for derailleur and drive train systems. Like AI, it seems to be everywhere, and instead of fighting it, we eventually have to learn to love it.
Historically, SRAMs completely wireless AXS systems have led the charge for mountain electronic groupos. Shimano finally caught up in May of 2024 with the release of the GRX Di2 12-speed system for their gravel lineup, however it was limited to 2x systems until June 2025 when the company released a fully wireless 1x12 speed version. Additionally, they released their long awaited first fully wireless Di2 system with the XTR Di2 platform (June was a bustling month for our friends at Shimano). While XTR has been wireless in the past, it had been almost 10 years since it saw an update. Hence, the componentry powerhouse relied heavily on its cable actuated systems to power mountain bikes until that change.
So what are the big differences between the new GRX Di2 and XTR Di2 systems? Is it just fancy rebranding? No, not quite, but let us break it down for you.
Finally, fully wireless shifting
With the release of both new systems, Shimano has finally joined the world of what some call "proper wireless shifting" - no battery in the seat post or frame and no messy wires that are easily damageable. Like the SRAM AXS system, GRX and XTR now have a removable battery in the derailleur. Longevity is equivalent to that of the SRAM AXS batteries – roughly 600-1000 miles of riding (factors like weather, amount of shifting, battery age can all contribute to this). Both systems offer more gear range, better shift quality, and are cross compatible with systems within the Shimano family (more details below), making them the hottest new components of the summer.
GRX Di2
The new Shimano GRX Di2 is a fully wireless gravel groupset, making the release of the system a major milestone for drop bar enthusiasts. Featuring a long cage rear derailleur that houses a removable battery, the system has refined ergonomics that allow for more precise and reliable shifting. The system talks nicely with either a 40T or 42T front chainring paired with a 10-51T cassette, giving the system extensive gear range for the terrain gravel grinders often like to challenge themselves with. It uses the existing 12-speed wireless GRX shifters and brake levers. The RD-RX827 derailleur is low profile and has a skid plate, making it more robust and durable to match the often rough terrain the system will face.
The beauty of the new rendition of the GRX system is that it can be mixed and matched with any 12-speed shifters, derailleurs, cassette, chains, and cranksets within the Shimano family, although it is best to use components from the same series or category to ensure full functionality. These systems include XTR, XT, SLX and Deore. It can also be combined with any 12-speed Di2 shift levers. An upgrade kit is available, helping make the jump to this new system easy and affordable if you already have bits and pieces of the puzzle.
XTR Di2
XTR Di2 is Shimano’s mountain bike counterpart of their fully wireless electronic groupset. Backwards compatible with any existing 12-speed cable-driven cassettes and chains, it allows for lots of mixing and matching with other Shimano components. The cassette has two range options – 10-51T or 9-45T. The smaller cassette offers better clearance at the bottom of the cage and, for those looking to keep it light as a feather, it saves you 70 grams compared to its larger sibling without sacrificing range. Shimano coins this as the “racer permutation” of the drivetrain.
Additionally, the derailleur went through some changes to make it more robust, while also making it sleeker and slimmer. The derailleur has been tested to ensure that, in a crash, the hanger is what takes the hit, instead of the der itself. It also has replaceable plastic bumpers in common impact areas and a new impact recovery system that should allow it to take a hit, reset, and keep shifting. There is also no longer a clutch system, which has been replaced with a dual-spring system to keep the chain tensioned, while also allowing you to remove the wheel. What does this mean? Less maintenance and lower risk for user error given that the clutch system required frequent TLC that many folks disregarded. Like the GRX system, the battery is finally inside the derailleur - it is removable and rechargeable and eliminates the wiring that was previously needed for the electronic Shimano systems to work.
Worth the upgrade?
We think yes. The new GRX and XTR Di2 systems offer unmatched speed and smoothness when compared to previous iterations of the platforms. Enhanced design features and durability help protect the system and reduce the amount of maintenance to keep it working smoothly. The backwards compatibility with existing 12-speed systems allow for upgrades of specific components instead of the entire drivetrain, creating a more budget-friendly option for adding a premium system to your gravel or mountain bike. This option alone makes it very feasible to adopt wireless shifting on a bike with an existing Shimano 12-speed mechanical drivetrain. And last, but certainly not least, the fully wireless system offers a much tidier cockpit than Shimano has ever been able to offer before, helping create a sleek and streamlined look on your dirt machines.