Sram XX SL Eagle Transmission: Does the premium drivetrain hold up in the 3000 kilometre endurance test?

Sram XX SL Eagle Transmission: Prices & weights at a glance

• Rear derailleur: 414 grams / 700 euros (without battery)
• Battery: 24 gram / 49 Euro
• Crank handle (with chainring): 458 grams / 660 euros
• Controller: 46 gram / 240 Euro
• Cassette: 347 gram / 720 Euro
• Chain: (126 links): 265 grams / 180 euros
• Total: 1554 grams / 2650 euros (with power meter 3250 euros)

When Sram presented the new Transmission drivetrain in the spring of this year, it was a bit of a shock. Somehow everything was just like the previous Eagle AXS drivetrain. Wireless transmission, 1x12, bandwidth. And yet it was a radical reinvention of the drivetrain. The transmission derailleur is no longer bolted directly to the frame via an extra derailleur hanger, but via a UDH link. The gradation of the sprocket is finer. Sram also promises a completely new level of shifting performance and maximum component durability. The latter point in particular is of great interest to bikers who are flirting with the high-end XX SL version. After all, the sprocket set alone costs an incredible 720 euros. The chain costs 180 euros. Amounts that nobody wants to invest every few months. Can the Transmission SL XX withstand hardcore use over many months? To find out, we pushed the drivetrain to the limit for a season.

Lightweight, expensive, exclusive: But can the Sram XX Eagle Transmission drivetrain withstand continuous use?

The Sram XX SL Transmission had to pass its first major test even before its official market launch. I, the BIKE reporter, had got hold of a test group. To find out whether the marketing text in the press release stood up to reality, I signed up for the toughest race taking place at the time. The infamous 24 hours in the Old Pueblo in Tucson/Arizona. The race is one of the oldest 24-hour races in the world and offered the best conditions for a concentrated hardcore test: a dusty desert course with an endless ensemble of short climbs that placed the highest demands on the gears.

Almost 300 kilometres were covered in the 24 hours. My conclusion: The functional difference to the classic Eagle AXS was not too great. However, the chain shifted gears noticeably more smoothly when shifting hard, as is the case in stressful racing situations or sudden obstacles. There was none of the cracking that we are used to. And therefore no fear of the chain breaking. Apart from a temporary chain jump, which was apparently caused by the fine desert dust that had crept into the chain links, everything worked perfectly. After cleaning the chain, everything ran perfectly again. The signs of wear on the filigree, milled cassette made of hardened steel (gears 4 to 12) and specially coated aluminium (gears 1 to 3) were also limited. Apart from tiny, superficial nicks, the racing use had left no traces. Astonishing.

The drive was also inconspicuous in subsequent everyday use. Short, fast after-work laps alternated with day tours. In between, we went to the bike park from time to time. The new gear pods proved to be pleasant. They look a bit clunky, but are more intuitive to operate than the older paddle shifters. The battery performance of the rear derailleur was also positive. Once charged, cycling was possible for weeks. Occasional cleaning and oiling was all I had to do apart from charging the battery. The XX SL Transmission components proved to be robust and reliable during this test phase. But would it stay that way? Because now the ultimate endurance test was about to begin. For the Transmission. But also for me.

Maxxis BIKE Transalp: The ultimate endurance test for the Sram Transmission premium drivetrain

The Maxxis BIKE Transalp is one of the toughest mountain bike races in the world. The race, which celebrated its premiere in 1998, triggered a gigantic marathon boom and is considered the mother of stage races. Now it was the 25th edition, which I wanted to ride together with my buddy Tino, who had already been my team partner at the first edition in 1998. Even the sober route data gave me an idea that it would be an endurance test by every trick in the book. 500 kilometres and 17500 metres in altitude from Nauders on the Reschen Pass to Riva on Lake Garda, divided into seven hellishly difficult stages.

The Scott Spark with the Sram XX Eagle transmission was the perfect bike for this endurance test. Light, but stable enough. With a retractable seat post, grippy tyres and two bottle cage positions. With fully charged batteries for the rear derailleur and the radio-controlled Rockshox dropper post, we set off. Everything on the bike was still original. The chain, the cassette, the chainring. Let's see if that would still be the case at the end of the race.

Tino and I had planned to tackle the stages in relaxed mode. But you can forget that when your body is made up of racing atoms and you have a race number on your handlebars. We set off at a brisk pace on the first climb, which was sometimes moderate, sometimes steep and then led up to the sky. The new, ergonomically perfect pods came into their own when constantly shifting up and down. The thumbs hit the pulse generator in every situation without searching. Left and right. Because in the technical downhill terrain, there was a lot to do for the telescopic support controlled by the left shifter. Ducking away, extending, ducking away again. The stabiliser has never had to work so hard.

Suddenly a grinding noise: the cause is quickly found

The gears worked without rattling or cracking. However, when racing along on the flat sections, I noticed a grinding noise that I had never heard before. It must have something to do with the position of the gear cage. It wasn't a loud, alarming noise. Just a constant, sonorous grinding. As soon as I shifted up a gear, it was gone.

So after the second stage, it was off to the Expo area, which resembled a VIP area. Every participant received technical support if required. Participants who rode a Scott bike and received the complete programme at the Scott stand were in paradise. All you had to do was hand in your dirty bike from the stage to the service crew and get it back an hour later. Serviced and checked. With a freshly oiled chain. And all the bells and whistles. The mechanic immediately recognised where the grinding was coming from. The derailleur cage was too close to the chainstays in the highest gear, causing the chain to grind. According to the expert, however, this was not due to the load on the BIKE Transalp, but to an incorrect basic setting during initial assembly. The problem was solved in a few simple steps. No more noise. Just marvellous silence when pedalling. Perfect.

The race pushed the equipment to the limit. The route was a mix of everything that mountain biking is all about. Long climbs. Winding trails. High-speed descents. Gravel, roots. Forest floor, even a bit of tarmac. The brake pads were sanded down after the fourth stage. But the drivetrain remained unimpressed by the conditions. The control LED on the gearstick battery was also green until the end of the race. Recharging was not necessary.

After a technically extremely demanding seventh stage with the roughest trails and treacherous downhill sections, Tino and reach the finish in Riva. Tired and happy, just like in 1998. A perfect moment. For the souvenir photo, we raise the bikes that have faithfully carried us over the 500 kilometres. Back at home, I take a closer look at the individual components of the XX SL Eagle Transmission.

Searching for clues: How much have the 3000 kilometres taken their toll on the transmission drive?

The rear derailleur looks worn, but this is primarily due to its unwashed condition. Technically, everything is still in perfect condition. Nothing is worn out. Nothing rattles. Nothing is stiff. Nothing is bent. Only a few superficial scratches in the aluminium tell of the hard use of the past months. Practical: Sram offers parts such as the outer parallelogram for replacement. If you value an impeccable appearance, you can simply replace scratched parts.

The Magic Wheel of the rear derailleur is an exclusive feature of the XX SL version. The outer plastic ring floats on the actual aluminium roller. If a stick or branch gets jammed in the pulley, the outer toothed ring continues to rotate on the blocked pulley. This protects the expensive carbon cage from damage.

Even after 3000 kilometres and with the dirt of the BIKE Transalp, the Magic Wheel still works, as a test proves. Dust and mud have not made the outer gear ring sticky or stiff.

The derailleur pulleys have well-sealed, smooth-running bearings. The check shows that they still run as smooth as butter. Corrosion is also not an issue. Corroded, rough-running bearings are often a problem with derailleur pulleys. Replacing them can be expensive. A replacement set for the Eagle top groups costs just under 90 euros. Good if the pulleys are durable.

Amazing! The delicate XX SL cassette only suffered minor damage during the hardcore use. The lower nine sprockets made of hardened steel have hardly been affected by the continuous use. And even the large aluminium sprockets hardly give any indication of the 3000 kilometres ridden. We would not have expected that. We would have expected the aluminium sprockets in particular to show signs of heavy use, including shifting notches. The cassette with its even gradation is convincing across the board. Nevertheless, 720 euros is still a price beyond good and evil.

The UDH mount makes the Transmission drivetrain unattractive for owners of older bikes with a conventional derailleur hanger. However, if the bike has a UDH link, Transmission is recommended. The rear derailleur sits bombproof and the distance between the cage and cassette is always optimal. The battery was also impressive. It lasted a long time. Several weeks without recharging is no problem. Once the battery was empty because I had put off charging it. Fortunately, the Rockshox post has the same battery, so I was able to clip it onto the rear derailleur.

No mud, no moisture: the contacts remained clean despite numerous trips in the rain and mud. That's a good thing. If the contacts were to corrode, it would only be a matter of time before the gearstick would start to tick.

The flattop chain with the milled plates is fully trimmed for lightweight construction. It received regular, but not excessive care. After the BIKE Transalp it was still tight on the drivetrain. Despite having covered 3000 kilometres, it has not yet had to be replaced. That's good, because the chain costs an insane 180 euros. The chainring with the special T-Type teeth, which is only reserved for the Transmission line, also shows no real wear.

The hollow carbon cranks of the XX SL line represent what is technically feasible. They are light and stiff. They are not scratch-resistant, which is why they are supplied with rubber protective caps. You should leave these on and not, like our tester, remove them for the sake of a cleaner look. In this case, scratches are inevitable.

The classic XX AXS groupset has paddle shifters, which are not everyone's cup of tea. The new pods look a lot chunkier, but their feel is close to that of classic shift levers. In our test, the shifters were convincing all round. The button cells last a long time and did not need to be replaced. The pods can be adjusted in any desired position on the handlebars. And the button assignments can be customised according to your own preferences using the AXS app.

The twelve sprockets sit close together. Nevertheless, dirt did not become so firmly embedded that the function was impaired. The photo shows how evenly spaced the sprockets are. With the classic Eagle cassettes, the jump from the penultimate to the last gear is enormous. This is a weak point of the older cassettes.

After many more tours and a few visits to the bike park, the season is now drawing to a close. As a tester, I am admittedly a little disappointed that the SL XX Eagle Transmission remained so unimpressed by my endurance test, which cost me hectolitres of sweat. As a biker, however, I am delighted with the quality of the components. I would not have expected that.

CONCLUSION Henri Lesewitz, BIKE reporter

I know from years of personal experience that the Eagle drivetrains are extremely durable. I have ridden many thousands of kilometres with them, almost always without any problems. However, I was sceptical about the XX SL Eagle Transmission. Because of the filigree cassette and the milled chain. And also because of gimmicks like the floating Magic Wheel. I would have expected the cassette in particular to show clear signs of use and wear during hardcore use. I'm impressed that the drivetrain still works like it did on the first day after almost 3000 kilometres.