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The year 2025 is characterised by the wooden snake. It is said to symbolise wisdom, growth and happiness - at least according to the Chinese calendar. I don't believe in zodiac signs or horoscopes, but somehow there seems to be something to it this year. Because there has indeed been astonishing growth in the field of circuitry. Eleven years after the introduction of the first electronic MTB drivetrain, Shimano has finally presented its wireless version of the XTR Di2 - and at the same time also launched the more affordable XT and Deore wireless drivetrains.
However, anyone who has already predicted the end of the shifting train has misinterpreted the signs in the cycling sky. Because the competition on the other side of the Pacific also had growth to report: With the mechanical Eagle 90 Transmission, Sram made its T-Type technology, which dispenses with derailleur hanger and adjustment screws and promises extremely precise shifting, accessible to electric refuseniks.
Mechanically upwind
Which brings us to the subject of luck. Because there has been a long lull in innovation, especially in the mechanical sector. After all, Shimano's all-time classic Deore XT has been on the chain for more than six years since the last facelift. And from the Americans, who are known for leaving out supposedly superfluous things - see front derailleur and second chainring - it wasn't exactly to be expected that they would give shifting by cable another chance. Of course, we were curious to see whether the new full-mount connection directly on the frame would pay off in terms of shifting precision and how doing away with the adjustment screws would affect the setup. Can the somewhat aged Shimano XT still keep up, or are the Japanese losing out when it comes to mechanical groupsets?
Shimano XTR Di2: Electric competition for Sram
Fortunately, this year Shimano has finally taken the "leash" off its electronic shifting systems, sending shifting commands to the rear via radio instead of cable, which could shake Sram's dominance. The developers took seven years to do this. The result is an XTR Di2 that is similar to its American counterpart in many respects, but differs significantly from the Transmission drivetrains in fundamental respects. While the Americans attach their rear derailleurs directly to the dropout of the frame, the XTR is still attached to the derailleur hanger - which is why adjustment screws are still required for setup.
The Shimano shifter has a mechanism that mimics the shifting feel of classic triggers. The XX Eagle, on the other hand, is controlled by a reduced controller with a digital feel. On the American side, a friction damper calms the gear cage, while the Japanese use a double tension spring to reduce chain slap. The new XTR Di2 is fast and furious, while the XX Eagle Transmission is as precise as clockwork - whether on motorised or analogue bikes. Shimano offers special derailleurs and cassettes with so-called Linkglide technology for e-bikers - more robust, equipped with special shifting lanes, but reduced to eleven gears.
Protection for expensive technology
The fine-tuning and customisation via app is similar for both systems. Both manufacturers also rely on comparable technology to protect the ultra-sophisticated rear derailleurs: in the event of rock contact, the rear derailleurs move inwards via a slipping clutch and then automatically return to their previous position. We were able to test both systems intensively against each other and reveal which of the new derailleur additions is the last word in wisdom.
The original question was actually: Who builds the better wireless drivetrain? Shimano or Sram? But now I'm asking myself: isn't the mechanical Eagle 90 Transmission perhaps the best MTB drivetrain? - Stefan Frey, BIKE test editor
Shimano vs Sram - The prices at a glance
Sram's XX Eagle is likely to leave something of a black hole in most accounts. Shimano's new XTR is almost 400 euros cheaper, but realistically still exorbitantly expensive. The good thing about the wireless groupsets: If you go up to XT or GX level, for example, you can save more than half the price on the cassettes alone, and still easily 200 euros on the derailleurs, without having to compromise on function. The somewhat outdated Shimano XT is unbeatable value for money. However, the new Eagle 90 transmission from Sram offers better value for money.
The weights in comparison
The new Shimano XTR Di2 saves weight, especially on the rear derailleur, thanks to the classic connection via the derailleur hanger, but the gear lever with its mechanics weighs more heavily. The higher weight of the XX rear derailleur pays off in a stiffer connection to the frame and extremely precise shifting. To be fair, if you subtract the chainring guard, the Sram XX at 1659 grams, undercutting the XTR by almost 100 grams. The Eagle 90 Transmission clearly loses out to the extremely light XT rear derailleur and the amazingly light XT crank. At just over 800 grams, the Eagle 90 crankset is a real heavyweight. A lightweight crank from a third-party supplier could save a lot of weight here at a reasonable price. Only with the cassette does Sram secure a lead.
Additional features via the app
Whether Sram AXS or Shimano E-Tube - the respective app is the interface to the electronic shifting system and opens up further setup and setting options, such as fine-tuning the gear steps or assigning the controller buttons. System updates are also installed via the app. While the AXS app recognises available components directly, Di2 components must first be set to pairing mode. With Sram, individual components can be assigned to the bikes on which they are mounted. This means you always have a good overview of your "garage".
If you forget to manually disconnect the connection to the rear derailleur in the E-Tube app after the setting, you will have to pull your smartphone out of your trouser pocket again the next time you shift gears at the latest. The connection is established a little quicker with Sram.
The points in comparison
The Shimano groupsets, especially the new XTR Di2, score with ultra-fast shifting. In terms of weight, the XT can make up some ground on the Eagle 90. The clearly structured setup clearly speaks in favour of the Sram groupsets. As far as shifting precision is concerned, the transmission derailleurs are the measure of all things - the mechanical Eagle 90 in particular leaves the somewhat outdated XT far behind.
Stefan Frey
Editor
