10x World Champ Bike: Prototype SRAM XX1 Eagle AXS derailleur on Nino Schurter’s Scott Spark

Prototype SRAM XX1 Eagle AXS derailleur on Nino Schurter’s Scott Spark: 10x World Champ Bike Check

Nino Schurter is certainly the single most frequent subject of our Pro Bike Checks, but we have plenty of reasons… like that he just won a record 10th UCI MTB XC World Championship on this Scott Spark RC… or that it’s built up with a Blackbox prototype SRAM XX1 Eagle AXS drivetrain with a new direct mount derailleur that ditches the derailleur hanger (and a few more extra bolts), plus a new cassette and a chain lighter than SRAM Red.

Yeah, Nino keeps winning, and SRAM keeps giving him prototypes to test out, too.

So what do we know?

Nino’s Scott Spark with SRAM prototypes

c. Scott

The first thing you might notice is that there aren’t a ton of close-up bike photos of Nino’s bold Scott Spark RC bike floating around on the internet after his record-setting 10th UCI XCO Elite World Championship win over the weekend. It wasn’t so long since we profiles his special 9x World Champ rig for a Pro Bike Check at the start of the season. Usually, brands jump to show off the bike that just won Worlds, but with an unreleased prototype drivetrain from team title sponsor SRAM, everyone is keeping tighter control over those hi-res promo photos.

But Scott couldn’t resist sharing a few to celebrate N1N0’s tenth World Champion title…

SRAM XX1 Eagle AXS prototype details

c. Scott, photo by Michal Červený

And between digging through social media and some more of the team’s own photos, we found plenty of public domain shots to get a good sense of what’s coming…

Before looking at the prototype AXS derailleur itself, that FlatTop chain is something new – on or off-road. First debuted with road SRAM Red eTap AXS back in 2019, the flat-topped chain promised increased ultimate strength, improved durability, and even less noise from the narrower plates of the 12-speed chain that reduced contact with the other cogs on the cassette.

That cassette is also all-new. Current top-tier Eagle cassettes get 11 cogs machined from one X-Dome block of steel & a single alloy big cog. But this new Eagle SL cassette appears to have 9 smaller X-Dome machined cogs from a single block, and on top of that 3 big alloy cogs pinned together with the middle of the three serving as the lightweight carrier.

c. Scott, photo by Remi Fabregue

Now all those improvements finally will make it to 12-speed Eagle drivetrains,  too. In fact, this new SRAM XX1 Eagle mountain bike FlatTop chain also gets hollowed-out side plates to save more weight, likely ending up even lighter than 11sp or 12sp Red road bike chains! Interestingly when SRAM debuted FlatTop, they said it was specific to 2x drivetrains. That looks like it has changed now.

Peeking out behind Nino’s foot here during the race, the top of the prototype SRAM XX1 Eagle AXS derailleur looks much more robust than what you have now with the current Eagle derailleurs.

c. Scott-SRAM MTB Racing

That’s because this new BlackBox SRAM Eagle AXS derailleur prototype ditches the derailleur hanger in favor of a design directly mounted to the frame. The direct mount interface looks to take advantage of patented tech that we spotted all the way back in 2018, and can even work with both current 12mm thru-axles or stiffer next-gen 15mm rear axles. It’s a topic our friend at WheelBased dive into again a year and a half ago in another SRAM patent update.

Direct-mount prototype SRAM Eagle AXS derailleur – Pros & Cons

As we saw in a few different views, the direct-mount derailleur clamps on both sides of the carbon frame’s dropout, attached to the end of the rear thru-axle.

No doubt, this will provide a stiffer connection between derailleur and frame. That’s a welcome improvement as the long cages, tightly-spaced 12sp cogs, and huge variation from a 10 to a 52T Eagle cog have meant perfect derailleur alignment is crucial for good shifting. Even a slightly bent hanger will mean a noticeable loss in performance and jumping or at least rubbing gears.

What’s missing?

c. Swiss Cycling

Quite interesting of note is something that’s missing here…

Underneath the standard AXS battery, there are no longer any mechanical hi/lo limit screws in their conventional location. With the horizontal position of the derailleur fixed relative to the inside face of the dropout since it bolts directly between the frame & axle, the relative position of the Eagle cassette is fixed, and maybe no mechanical limit is needed? Or perhaps the shift motor is just now limited electronically, and will be managed wirelessly through an AXS app update?

What else we can’t really see from the outside is that familiar Torx bolt of SRAM’s mechanical Type 3 Roller Bearing Clutch. Current Eagle AXS derailleurs hide it a bit, but it’s still there. These prototypes have a completely different P-knuckle profile, though.

And if we had to venture a guess, we wouldn’t be surprised to find that lower-drag hydraulically-damped clutch tech we uncovered back in 2018, not hiding inside this next-gen Blackbox derailleur.

 

A stiffer and more robust derailleur-frame interface will surely improve shifting. But the obvious downside in getting rid of the sacrificial derailleur hanger is that when you crash, that impact is going into your frame and derailleur, and not a low-cost hanger.

If you break a SRAM UDH, that’s an 18€ replacement cost. Replacing a current XX1 Eagle AXS would cost 831€ and a Scott Spark RC HMX frameset would be 5200€ (although hopefully, Scott would at least just get you a new rear end for less, if not covered by warranty.)

c. Scott, photo by Michal Červený

With that said, Nino Schurter pushed the bike pretty hard and looks to have gone down pretty hard right onto that new prototype BlackBox SRAM Eagle AXS derailleur during the race (check that Insta-video above) and nothing was damaged enough to prevent him from winning his 10th World Championship.

UDH compatibility means SRAM direct-mount derailleur compatibility

The other downside in any new proprietary “standard” like a direct mount derailleur is limited backward compatibility. And here we might be finally seeing the brilliance of why SRAM has really been hyping their UDH standardized Universal Derailleur Hanger.

We loved the actual universal fit concept of the UDH when it debuted at Eurobike in 2019 (curiously 10 months after we first spotted the direct mount derailleur). But it only took us a week to put two and two together to realize that the Universal Derailleur Hanger concept could mean UDH direct-mount derailleur compatibility, as well.

Now that looks to be the case. We’ve spied other current bikes from Trek & BMC fitted with this new Prototype SRAM Eagle AXS rear derailleur, suggesting all you will need is a UDH-ready frame to make it work.

c. Swiss CyclingSo how long until these new prototype SRAM Eagle AXS components make it into production and out to consumers? We can’t really be sure. When we met with SRAM’s MTB team at Eurobike just a month ago, they said they didn’t have anything new to show us for the time being. We had heard rumors of this new derailleur peeking out in race practice since at least the start of this XC season, though.

c. Scott, photo by Michal Červený

The UCI MTB World Championship seems to be the first time it came out to race on more than one bike suggesting two things. One, there’s enough of a perceived performance improvement that the best riders in the world decided they wanted that edge over some of the competition. And two, if these pros are willing to be guinea pigs with rainbow jerseys on the line, the kinks have been ironed out and these components are likely very close to production, if not already ready.

It won’t be long now.