Sram XX SL Eagle Transmission: Sram's new supergroup in the BIKE endurance test
Henri Lesewitz
· 21.03.2023
With the Transmission, Sram presents the fetishistic optimisation of the proven AXS drive. Despite radical innovations, much has remained the same. The number of gears is the same. As is the radio technology. The focus during development was on maximising shifting performance and durability. Does the concept work? We have been using the top XX SL groupset continuously for months and have also ridden a 24-hour race with it. Is the expensive supergroup worth it? Here is our experience report.
At the Mountain Bike World Championships in Les Gets 2022, the first Prototypes of the new Sram AXS drivetrain late. Now it's here! The press release on the brand new Eagle Transmission is off the scale. The PDF alone, which lists all the innovations and variants of the new drive, is 57 pages long. You click through the document in amazement and are almost overwhelmed by the multitude of technical clous. However, the one thing that was actually expected after the evolution from 2x10 to 1x11 and the subsequent 1x12 is not to be found on the 57 pages: the step to 1x13. That's the really amazing thing. Sram has renovated the entire Eagle AXS drivetrain, but is sticking with twelve sprockets.
A 13-speed gearstick would have meant too many compromises. What's more, we couldn't see what huge benefits it would have brought - Frank Schmidt, lead engineer on the Transmission project
Sram XX1 AXS vs. Sram XX SL Transmission: The difference becomes apparent on the steep section.
The most important innovation compared to the previous Eagle XX1 derailleur: The rear derailleur is no longer bolted to a classic derailleur hanger, but sits on the rear wheel axle thanks to the fully integrated UDH-Link. This ensures that it is always optimally positioned in relation to the cassette. First shake check: The rear derailleur sits firmly and without play. Practical side effect: The position of the rear derailleur is always optimal and no longer needs to be fine-tuned after screwing it on. This is why (unlike the previous XX1 AXS rear derailleur) neither a loop loop nor screws for adjusting the upper and lower stop. 1:0 in favour of transmission.
Sram offers the new Transmission drivetrain in three versions. The X.0 version with an aluminium crank marks the entry level and is available as a complete set for 1900 euros. The lighter XX, equipped with more sophisticated materials and more extras (e.g. Magic Wheel), costs 2450 euros. The high-end XX SL version, which is fitted to our test bike and weighs just 1554 grams (gears, controller, cassette, chain, crank) thanks to consistent lightweight construction, costs 2650 euros.
This makes the Sram Eagle Transmission the most expensive groupset in the world. 2650 euros. A crazy price! Expectations are correspondingly high. Firstly, a direct comparison with the old, almost 700 euro cheaper XX1 AXS. I first ride up a steep climb with the previous drivetrain and then with the Transmission, shifting under full load in each case. The clear conclusion: the transmission works noticeably smoother. Even at full pedal pressure, the gears engage surprisingly smoothly. With the previous gearstick, this feels much rougher, harder and more archaic. Under full load, it really cracks. 2:0 in favour of Transmission.
What is also immediately noticeable: the new controllers, which are now called pods, are much more intuitive to operate than the original rocker of the AXS XX1 or the retrofittable rocker paddle. Instead of a rocker, they now have a two-button design. Every finger twitch fits. The controllers are no longer as discreet as the previous models. However, they can be optimally adjusted to personal requirements on the handlebars. 3:0 for transmission. Great: The new pod controllers are compatible with the older AXS derailleurs.
Programming is carried out as usual via the AXS app. In addition to the button assignment, you can programme whether you want to shift click by click (sequential) or in one go (multishift). I, the BIKE reporter, prefer the single-click mode.
The outstanding shifting performance of the Transmission drivetrain is due to the interaction of many small details. The cassette, chain and chainrings are designed as a system. The Cassette of the XX SL is a marvel of technology. The material, shape of the teeth and shifting aids are the result of intensive development work. Sram's prototype department in Schweinfurt is famous for immediately realising the engineers' ideas so that innovations can be tested directly on the trails. What convinces there is maltreated in the in-house test laboratory until the last weak point has been eliminated. The XX1 cassettes have already proven to be extremely robust and reliable in the wear and endurance tests of recent years. The new Transmission version is set to top this.
A welcome innovation: the gear jumps in the lower gears are no longer as large. The gradation is finer. With 10/52 teeth, the bandwidth is still 520 per cent. Instead of the 36 and 42 sprocket, however, the transmission cassette has 38 and 44 sprockets. These are made of aluminium in the SL version (unlike the XX and X.0), just like the 52 mm sprocket. This makes the construction of the cassette highly complex and is primarily due to the weight. 347 grams is an impressive value. However, the price of the SL cassette makes you swallow dry: 720 euros! This naturally raises the question of how wear-resistant the whole thing is.
The answer is: everything is in the green. The filigree XX SL cassette, which has an extra-hard special coating, has not been affected much by our almost 2000 kilometres of testing so far. This is all the more astonishing given that it was exposed to wintery muddy weather as well as the dust of the Sonoran Desert in Arizona. While the nine steel sprockets hardly show any signs of wear, the three aluminium sprockets have at least small marks in some places, which are evidence of hard shifting. However, these are so minor that they are not critical and have no effect on the function. However, it will be a long time before the cassette needs to be replaced. When the time comes, you'll have to decide whether you want to fork out 720 euros for the XX SL replacement or whether the X.0 version will suffice. At 376 grams, it weighs just 29 grams less, but is available for 480 grams. The pure function is identical.
In terms of gradation, shifting behaviour and weight, the new cassette scores over the classic XX1. Intermediate score: 4:0 in favour of Transmission.
ATTENTION! The classic, significantly cheaper Eagle cassettes cannot be used with transmission parts. The freewheel standard is the same. But the position of the cassette is different. And the shape of the teeth is also fully designed for the new flattop chain. We already know these chains from Srams Road bike gears eTap AXS. With their straight top edge, they look sharp as a rat, but unfortunately they also put a much bigger dent in your bank balance than the classic Eagle chains. The cheapest X.0 version costs 120 euros. The premium version of the XX SL chain with milled plates burns a really big hole in your wallet at 180 euros.
With Transmission, Sram presents another clever feature that is particularly interesting for racers. The cranks can also be ordered with a power meter. The cranks, which are available in four sizes, are extremely easy to change thanks to a new, simple fastening system. For example, to spontaneously adapt the gear ratio to the route.
The difference between the new XX SL Transmission and the classic Eagle AXS XX1 is not too noticeable on relaxed rides around the house. Everything works unobtrusively and exactly as you would expect from a groupset. But this is also the case with the XX1. As already mentioned, a 1:1 comparison reveals some plus points in favour of the transmission system. However, the huge price difference is not necessarily noticeable in normal touring use. Of course, the basic functional principle is the same. That's why the battery lasts about the same time with both systems: 20 to 25 operating hours according to the manufacturer. In practice, however, it feels like it lasts forever, as you quickly get used to the battery management and therefore never run the battery down.
What does it look like in tough racing conditions, for which the XX SL was developed? To find out, I, the BIKE reporter, took part in the 24 Hours in the old Pueblo, one of the oldest and most legendary 24-hour races in the world. The conditions in the Sorora Desert in Arizona were perfect for a hardcore test: sand, rock, extreme temperature fluctuations and constant changes in gradient.
I've never driven a 24-hour race in February before. And then there's the solo category! But you can't take it easy on the trail in a race. The pack rushes off like it's on fire. The team riders in particular, who change after each of the 25-kilometre laps, are pushing hard on the gas. I have no choice but to keep up. On the narrow course, you would otherwise be the plug holding everything up. With a taste of blood in my mouth, I knead over the course, which consists exclusively of bends, short steep stretches and mini descents. The gear thumb is constantly busy. The XX SL does its job in a relaxed manner and sorts the gears. Even on the nasty steep sections, which keep rearing up in front of me without warning, the gears engage smoothly and without the usual clunk. I can concentrate fully on driving. Normally, I would briefly take the pressure off the pedal when shifting up to minimise the risk of a broken chain. You get used to this short release relatively quickly with Transmission. Super.
On lap two, I notice a slight grinding noise, accompanied by an occasional jumping of the chain. The cause is immediately clear to me: the fine desert dust has settled in every crack of the drive. But the chain jumping is unusual. Are individual chain links no longer able to move freely due to the dirt? I take the pressure off a little when changing gear. At the end of the round, I wipe the chain clean and re-oil it. Now everything works again. The grinding noises are gone. The gear changes are smooth. Fits.
That's how I do my laps. The drive works unobtrusively. The gear changes are precise. Up and down. And although the rear derailleur regularly comes into contact with one of the stones that are everywhere on the trail, the shifting performance remains precise. Thanks to the UDH mount, it sits so securely on the frame that even rough impacts do not cause the mount to bend, which would require readjustment.
The cranks react much more sensitively to stone contact. For visual reasons, I removed the original rubber cap from the pedal eyes. Not a good idea: now the crank arms have massive scratches in the carbon surface. Technically not so bad, but visually a disaster. My tip: Leave the rubber caps on. Even if it looks less elegant than clean crank arms.
After 24 hours, I fight my way to the finish with my legs worn down to the max. Unlike me, the XX SL Transmission would probably last another 24 hours. No signs of wear or fatigue. 270 kilometres and 4000 metres in altitude. Not a bad result for a February day.
Sram XX SL Eagle Transmission: BIKE editors' verdict
The Sram XX SL Transmission is an all-round perfect groupset and sets a new benchmark. It functions reliably, offers maximum shifting comfort and proves to be extremely robust in the endurance test. The most noticeable functional differences to the classic XX1 AXS are the smoother shifting behaviour under load and the new controller, which is much more intuitive to operate. Whether this is worth the considerable additional price of the Transmission depends on your personal biking ambitions and financial scope. If status and weight records are not so important to you, the X0 Transmission, which has the same functions but costs 750 euros less, could be a good alternative. - Henri Lesewitz, BIKE Editor-in-Chief
Sram XX SL Eagle Transmission: Prices & weights at a glance
Rear derailleur: 414 grams / 700 euros (without battery) >> available here
Battery: 24 gram / 49 Euro
Crank handle (with chainring): 458 grams / 660 euros >> available here
Controller: 46 gram / 240 Euro
Cassette: 347 gram / 720 Euro >> available here
Chain (126 links): 265 grams / 180 euros >> available here
Total: 1554 gram / 2650 Euro
