SRAM X0 & XX Eagle AXS Transmission New Tech

someone pedaling the sram eagle axs xx transmission mountain biking groupset in the woods with motion blur


New products from SRAM have been coming in hot and heavy recently, their new Eagle AXS Transmissions with T-Type components are no exception.

Yes, SRAM is calling them transmissions instead of drivetrains because they’ve been completely redesigned to work together as an interdependent system. While you can still mix and match between models of T-Type components, this new stuff is not cross compatible with the previous AXS components.

This article is all about the new tech on the transmissions, but we have a seperate article revieiwing SRAM Eagle AXS Transmissions. 

The transmissions come in three main flavors: X0, XX, and XX SL. All three of these transmissions offer super similar shifting performance on trail, but they’re designed for different disciplines of riding. The biggest thing setting them apart is their weight, with lighter materials like carbon fiber popping up everywhere as you move up the model range.

SRAM Eagle AXS Transmission Overview

New SRAM T-Type Features

  • Full mount rear derailleur

  • Better shifting under load

  • Flat top chain

  • Integrated bash guards

  • No b-tension or limit screws

  • X-Sync cassette

  • Redesigned shifter pods

Continued Features From Previous AXS

  • Wireless shifting

  • 12-Speed

  • 10-52 cassette

  • Overload clutch

  • Waterproof

X0 is their purpose built enduro option
XX is for both enduro and trail riding
XX SL is for cross country riding

Here at The Lost Co, the X0 trasmissions and XX transmissions tend to be our bread and butter because they’re both geared towards that trail and enduro riding that you know we love, so we’ll be focusing our attention on these two groupsets.

sram xx eagle axs tranmission groupset on a steel table with ferns in the back

SRAM XX Eagle AXS Transmission Groupset

sram xo eagle axs transmission groupset on a steel table with ferns

SRAM X0 Eagle AXS Transmission Groupset

Carry Over Features From Previous SRAM AXS

While there’s seriously a TON of new tech to unpack with this new T-Type stuff, first let’s quickly cover the features that are carried over from the original version of AXS drivetrains.

It’s still 12-speed wireless shifting using the same battery as before, it’s still super waterproof, and still has that coveted overload clutch which helps the derailleur protect itself from when you hit it with a hammer just for fun. This makes an excellent party trick, but more importantly keeps your fancy derailleur from exploding on impact when it kisses a cute rock.

The first version of AXS carried most of the same shifting technology from the cable actuated drivetrains offered at the time, and the big purpose there was to crack the code of getting the wireless shifter and derailleur to shift and function flawlessly. However, this new T-Type stuff has been designed as an entirely new system, meant to truly be the next generation of mountain bike shifting performance. SRAM claims the Eagle Transmission is a first of its kind approach to the mountain bike drivetrain that sets a new bar and new expectation to the whole system.

So how the heck does it work? Well, make some popcorn because it’s time to unpack a bag of new tech so big that most airlines will charge you to bring it onboard.

SRAM Transmissions Are Only Compatabile With UDH Frames

All of these new Eagle AXS Transmission groupsets are only compatible with SRAM UDH frames because all of the derailleurs are direct mount, which means they don’t even use a derailleur hanger!

detail sram xx eagle axs transmission derailleur

Most new bikes from the past few years have been designed with the UDH, so if you’ve bought a new bike recently, the odds of these transmissions fitting on your bike are pretty high. Plus it’s safe to assume pretty much every new bike coming out in the future is going to be built around UDH. If you’re looking at ordering one of these transmissions, definitely double check that your bike uses a UDH before checking out! Also something to note is that all these T-Type components are not compatible with the old Eagle drivetrains at all, with the exception of the shift controller. That means you can’t just buy the fancy new derailleur and slap it on your current eagle drivetrain and expect everything to work exactly how it was intended.

That being said, these groupsets are only being sold as complete packages at first.

The New Tech On SRAM AXS Transmissions, From Front To Back

Every single component is completely redesigned, so just like a spoiled kid on christmas, we’ve got a lot to unwrap here. We’re going to start at the handlebars with the shift controller and work back through the cranks, chainring, chain, cassette, and that brand new direct mount derailleur where all the magic happens. Let’s dive right in!

Shift Controller or Pod

  • Ultra adjustable

  • Backwards and forwards compatible

  • Comfy!

The new AXS pod controller is ultra streamlined and ultra adjustable!

You can spin it around, switch which side of the bars it’s on, change which buttons shift up and down, and even choose between convex and concave buttons.The adjustability comes from the new Infinity Clamp with its incredibly thin mounting interface and 360 degrees of adjustability around the bar and rotation of the pod itself. You can also opt for the new Bridge Clamp which mates perfectly with the MatchMaker standard we’ve gotten used to on other SRAM products.

sram axs shift controller pod leaning up against a cork

SRAM Eagle AXS Transmission Pod Controller

The shifter pod is also the only piece of this T-Type groupset that is backwards compatible with previous AXS, and the old shift controller is the only part that’s forward compatible with the new stuff!


  • XX SL and XX are carbon, X0 is aluminum

  • 165, 170, 175mm lengths

  • 30-38t chainrings

  • Integrated bashguards

  • All models are powere meter compatible
  • E-Bike specific options

Moving back to the crankset, there are carbon fiber and aluminum options. The XX crankset is carbon fiber with a foam core, and the X0 crankset is aluminum with a hole through the middle of each of the crank arms.

sram x0 and xx axs transmission cranksets on a table with ferns

SRAM X0 and XX Eagle AXS Transmission Cranksets

These X0 cranks are the lightest aluminum cranks SRAM has made, and I think they're the best looking cranks they’ve ever made. Also, all of the chainrings mount to the cranks with 8 bolts, which is kind of a lot, but it’s to make all of these new cranks power meter compatible in case you want to measure exactly how much fun you’re having on the climbs!

sram xx transmission mountain bike crankset on a table with plants

SRAM XX Eagle AXS Transmission Crankset

The new chainrings also have built in bashguards that can save the day next time you frame case a rock, and you can just pop a fresh one in to replace a busted one! A pro tip on these bashguards is to just leave the one that sits on the underside of the chainring when you’re descending to save a little bit of weight. Or if you’re crazy enough to switch your feet on the way down you can leave both on there! There are also e-bike options for X0 and XX cranks, which accommodate the mounting standards for all of the most popular motor options on the market.


  • Flat top

  • Slightly narrower

  • Moved material from sides of chain to top of chain

  • Strongest chain SRAM has made

Wrapped around the chainring is that new flat top chain. You might recognize the silhouette of this chain from their road and gravel groupsets, but this is not a copy paste situation, as this chain is specific to their mountain bike transmissions.

sram x0 and xx eagle t-type transmission mountain bike chains on a table

SRAM X0 and XX Eagle AXS Transmission Chains

This new design looks super sleek and is the strongest chain SRAM has ever made thanks to redistributing some of the metal from the sides of the links to the top of the links. It’s the strongest chain SRAM has ever made thanks to redistributing some of the metal from the sides of the links to the top of the links, which also makes the chain more narrow than their previous 12 speed chains. The thinner width combined with a newly redesigned bottom side of the chain lends a hand to create the best shifting performance of any SRAM drivetrain.

detail of the flattop sramaxs transmission chain


  • XD Driver

  • 10-52 tooth 520% range

  • X-Sync on all teeth (besides setup cog)

  • Shift ramping

  • Setup cog

  • Cassette mapping

  • Updated 2nd and 3rd gear for more uniform changes in gear ratio

The T-Type cassettes are also new but still mounted on the same XD driver. They’ve got the same 10-52 tooth range we’re used to on the previous eagle cassettes, but with refined gear progression in the easier gears with smaller jumps between those dinner plates.

The second and third gears each have two additional teeth to make for more consistent jumps between the easiest gears, and the other 10 cogs are the same size as previous AXS cassettes. Also, each of those cogs besides the seventh now use the X-SYNC narrow wide profile just like the chainring, which helps with chain retention and extending chain life.

sram x0 and xx eagle t-type transmission mountain bike cassettes on a table

SRAM X0 and XX Eagle AXS Transmission Cassettes

Reducing the distance between cogs also helps create smoother quicker shifts because the chain doesn’t have to travel as far or bend as much, which prolongs the life of the chain as well. You’ll also notice this red ring tucked inside of the seventh cog, which is used when setting up the transmission on your bike, and is the only cog without X-SYNC. Plus, it looks kinda cool too!

detail of the sram xx axs transmission cassette and chain on a mountain bike

These cassettes also have a cool feature SRAM refers to as cassette mapping that controls how the chain shifts through the cogs. More on that later, but first we have to talk about the most important piece of the puzzle, that new derailleur!


  • Full mount/hangerless interface

  • No b-tension/limit screws

  • Easy micro-adjust
  • Much stronger than previous eagle derailleurs

  • Inline cage

  • Magic wheel

Where do we even start with this thing?

Well like we mentioned earlier, the most obvious change is that there is no more derailleur hanger! These T-Type derailleurs mount directly to the frame, which SRAM refers to as “full mount” and a “hangerless interface” between the derailleur and frame. There are a couple of performance advantages to this design, and first we’ll talk about how it increases the strength of the T-Type derailleur.

sram x0 and xx eagle t-type transmission mountain bike derailleurs on a table

SRAM X0 and XX Eagle AXS Transmission Derailleurs

As most of us know, the purpose of that derailleur hanger was to save the derailleur when you inevitably smack it into a rock. The cheap hanger would break before your expensive derailleur, saving you hundreds of dollars every time you took a questionable line. So by building the hanger into the derailleur, they’ve had to make every piece of the mounting interface significantly stronger so that it won’t break when you clip a rock. SRAM says you can stand on these without bending anything, and of course we put them to test, which they passed with flying colors!

These T-Type derailleurs are seriously overbuilt when compared with previous the previous generations of AXS, and when paired with the overload clutch to protect it during impacts, this derailleur is one tough cookie. And if you do manage to break one, they’re way more rebuildable than previous SRAM derailleurs, with a fully replaceable cage, skid plates, outer link, and b-knuckle on these X0 and XX models.

The next benefit of a direct mount derailleur is that it drastically simplifies the set up procedure. The new T-Type derailleurs don’t even have b-tension or limit screws, because they don’t need them! SRAM is able to do this because the derailleur and cassette are now both mounted around the same point: the rear axle. That means there’s no concern about micro-adjusting the derailleur to be in line with the cassette because the only way they wouldn’t be in line is if your axle bends, breaks, or disappears.

sram xx eagle axs t-type transmission mountain bike derailleur on a table

SRAM XX Eagle AXS Transmission Derailleur

Traditional derailleurs used B-tension and limit screws to correctly align the derailleur with the cassette because they’re separated by the frame and hanger. With those two variables in play and no rigorous standards around their exact mounting locations, the derailleur had to be super adjustable to work on every different frame and hanger it was installed on. Now, by mounting the derailleur and the cassette around the axle, they’ll always be perfectly aligned. This makes installing the T-Type derailleur easier than anything else on the market. Micro-adjusting your montain bike's drivetrain has never been easier. If you’re a rider who’s always struggled to get their gears shifting perfectly at home, there’s no need to worry about those finicky little adjustment screws anymore.

You’ll also notice that the derailleur looks bent when you look at it inline with the chain, and that’s because it is! It’s called an ‘inline cage’, and it’s bent to point the chain back at the chainring in every gear to prolong the life of your chain and keep things a bit quieter. Also, the XX and XX SL derailleurs use what is called the “magic wheel”, which keeps spinning in the event you get a stick or something else jammed in the lower pulley. This could save your derailleur from getting yanked off your frame and ruining either your casual Saturday ride or your career defining race run.

How It All Works Together

So that’s enough about the individual bits, let’s talk about how it all works together! SRAM makes a huge claim, saying this drivetrain shifts better the harder you pedal during the shift! I’m going to say that again, this drivetrain shifts better the harder you pedal while shifting.

You might ask: "Hey, are you sure you’re reading that right?" I agree, it doesn’t make any sense but SRAM says that it shifts better while you’re sprinting.

This goes against everything we know about shifting a bike, so how the heck does this work? The combination of the stronger thinner chain, stiffer full mount rear derailleur, and tighter cassette spacing work together with what SRAM refers to as cassette mapping, which we haven’t really touched on yet.

tor climbing a rock with a sram x0 axs transmission on his mountain bike

Cassette mapping helps control when and where the shifts happen to make every shift as seamless as possible and honestly it’s pretty dang complicated! In a nutshell, it’s a blend of firmware in your derailleur and hardware in your cassette to control where the shifts happen on your cassette, and how fast they happen. This aims to help the chain fully engage on both the cog you’re shifting out of, and the cog you’re shifting into at the same time so there’s no moment where your chain isn’t completely engaged with your cassette and driving you forward. By using revised shift ramps and precisely timed movements in the derailleur, SRAM ensures the chain climbs up or down to the next cog in the optimal spot for the chain to engage with the teeth of both cogs at once, and lets you put power down the entire time through the shift.

tor climbing roots with a sram x0 axs transmission on his mountain bike

Now, we’re just like expensive race cars with no lift shifting, and we can stay on the power the whole way through a shift. This feature is a game changer whether you’re trying to make it up a technical climb where keeping momentum is key, or you’re sprinting off the line at the start of a race and need to go from your easiest to your hardest gear while sprinting.


So, who are these new transmissions for?

If you’re after the latest and greatest tech with the best performing groupset we’ve ever gotten our hands on, this groupset is your best option! If you’re chasing performance to give you an edge on the race track, the crisp and reliable shifts under load are going to save you time by letting you be less selective in choosing where you shift as well as not worry about snapping chains while pedalling through your shifts.

All the new tech packed into these transmissions has created a seriously impressive package and you can read all about our impressions of how it performs on trail in our SRAM AXS Transmission review blog post. 

Shop SRAM Eagle AXS Transmission Groupsets

Sold out
Sold out

Got questions? Feel free to shoot us an email or give us a call!




Tor Weiland



Bellingham, WA

Current Bikes: Transition Spire Custom Build

Bike Size: Medium

Favorite Trails: Oriental Express, Galbraith

About Me: Hailing from the sunny landscape of California, Tor headed north and landed here in the cloudy town of Bellingham, WA. His riding style is "PINNED" and he loves to scope out those seemingly impossible triples. He loves riding and also loves sharing his experiences with others. You can catch Tor in front of the camera or behind the keyboard, but best of luck catching him on the trail!