SRAM Launches New 12 speed XX1 & XO1 Eagle Drivetrains

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SRAM has been busy, designing what could be the best progression to date, in achieving uncompromised drivetrain performance. Rob took a trip to Massa Marittima in Italy to see what all the fuss is about.

XX1 - Rear Mech

Yes it’s 12speed, yes it’s new and yes, it’s gold. But what Eagle XX1 and XO1 (not gold unfortunately) presents, is, according to SRAM, much more than a 12speed drivetrain. It’s an evolved 1x system, which SRAM says has the potential to be the most durable, the quietest and the most responsive drivetrain we’ve seen.

XX1 - Merida

With… Eagle, you get complete freedom. Freedom to ride anywhere, everywhere, on any bike, without compromise.” – Chris Hilton, Eagle Product Manager.

It’s taken many of us some time to adjust to the premise of 1x drivetrains and losing the front mech for good. It’s a huge change that has happened pretty quickly, and even now, seeing some lower specification production bikes coming out into the world with 2x and even 3x drivetrains, is a head turner (and shaker). The whole 1x takeover is now even more prominent, with SRAM recently confirming it will never again manufacture a mountain bike front derailleur (check the video here). That’s worth re-stating. SRAM has said that it will never again make a front derailleur for mountain bikes. Even for the company that commercialised single-chainring riding, that’s a bold statement. And with this, it’s newest, flagship groupset, it aims to prove why you no longer need a front mech.

What SRAM is doing with Eagle is taking its philosophy of 1x drivetrains and attempting to make it better. By creating a system that is lightweight, more durable and simpler in design and usage, SRAM wants to remove the last remaining excuses or compromises as to why riders wouldn’t make that move to 1x. It seems like a simple solution, and in essence, it is.

XO1 - Cassette_02

Adding a 50 tooth sprocket to a cassette is a solution that has been thrown around a lot recently and although it seems like a pretty simple progression for the 1x systems, it is one that is going to have a much larger impact on riding than just a 12speed. (OneUp Components has got in there recently with its new Shimano-specific Shark system – here). SRAM has been able to play around with different cassette configurations behind closed doors, playing with different teeth on the largest sprockets to see what the potential benefits in performance could be. Looking at ratios, ranges and designs of their cassettes and by doing this they have developed a system that they say, will give the rider ‘unbelievable confidence in what they can achieve on a bike’.

Eagle Cassette

Eagle now provides a huge 500% gear range, which is roughly the same as a 2×11 drivetrain system. (Although you Rohloff Speedhub fans out there will happily argue that your drivetrains provide 526% range over 14 internal gears). But anyway, Eagle delivers all the benefits of any existing 1x system, in terms of having fewer parts on your bike, creating a lightweight drivetrain which is easier to use, but with the range of a 2x system.

XO1 - Rear Mech
The XO1 rear mech displaying the tidy Eagle logo.

All-new shifting features create a smoother, quieter system with enhanced inboard and outboard shift performance

In appearance XX1 and XO1 are quite different. Although they both have very smart Eagle graphics on the shifter triggers, XX1 is the slightly more outlandish and (in some eyes) attractive of the two, brandishing gold graphics on the shifters and mech and of course the gold chain and cassette, whereas XO1 has gone for red/grey graphics and a black chain. Both cassettes and chains are finished with a titanium nitrate (TiN) treatment – often used on super-hard cutting tools. This helps to reduce friction when the drivetrain is in use and adds corrosion protection resistance. The slightly differing PVD vapour within the TiN is responsible for the difference in colours, from Gold on the XX1 cassette and chain, to black on the XO1. In comparison to the previous 11-speed XX1 drivetrain, Eagle only adds around 50g to the whole group. The new ‘ultra-energy-efficient’ 12 speed XX1 now has completely redesigned hollow carbon crankarms making them 30g lighter compared to the tougher and more aggressive XO1 crankset. Weight has been saved within the previously mentioned crank arms, shifters and rear mech to counteract the added weight of the larger cassette. SRAM is adamant that the slight increase in weight is more than justified by the overall range and performance that is achieved when swapping to XX1 and XO1 Eagle from 11 speed.

XO1 - Shifter

Many questions were asked at the launch event in regards to fitting a larger cassette onto existing wheels and bikes. No one wants to pay a load of money for a shiny new drivetrain, and then have to get a new wheel so they can run it, or even a new frame with a wider axle width to accommodate the increase in size. SRAM didn’t want this either, and by making Eagle able to plug and play with existing xD driver bodies clears this up (assuming you already own one). The 50T sprocket has a dish-like design that follows the same angle as the spokes on a wheel, fitting 12 sprockets in while still using the same cassette driver body to give a 10-50T range. The XX1 and XO1 cassette comes with a range of 10,12,14,16,18,21,24,28,32,36,42,50.

Eagle XX1 - Cassette_02
Yep, all 12 are there.


Chain design and alteration was described by Chris Hilton, in charge of the Eagle project as having a ’tremendous amount of complexity’.

By getting stuck into the real detail, the way SRAM has performed this piece of technical trickery in space saving, is by altering minute dimensions in the spacing within the cassette sprockets and in the chain width. The previous iteration of XX1 had cassette sprocket spacing of 3.8mm compared to the Eagle design which has reduced this to 3.65mm. This seems like a small change, but across a new 12speed cassette, the saving in space has allowed an extra sprocket to fit in. Cassette spacing coupled with a chain width which has gone from 5.6mm to 5.25mm has given SRAM the room they need to give us, the riders, a drivetrain that is set to ‘improve riding performance’, with (as far as it seems) a significant lack of issues along the way.

From the words of SRAM itself – ’All-new shifting features create a smoother, quieter system with enhanced inboard and outboard shift performance.’

Eagle - XX1 Chainline_02

Chain design has been a section of the Eagle project that SRAM has really gone to town on. SRAM owns a chain factory in Portugal which was part of the old Sachs Bicycle Components company, acquired by the company in 1997. Here, SRAM has been able to develop a new chain for Eagle drivetrain, but in order to do so, it has had to make some huge changes and invest heavily in the project, which has included purchasing new presses to make the chain, new tooling and new assembly lines. Even the heat treating has changed to manufacture all the parts that go together to build a chain.

Eagle -Chain
There is a 31 stage press process in order to manufacture the new Eagle chain.

Chain design and alteration was described by Chris Hilton, in charge of the Eagle project as having a ’tremendous amount of complexity’.

Adding great precision to the new Eagle chain meant making the links extremely flat. The pins have always been the widest part of a chain, protruding slightly out of the plates (something you never really think about). But no more! Space has been saved by making the pins sit flush against the side plates of each link. On previous 11speed chains there was a sharp chamfer on the inside edge, where as now on Eagle chains, there is a subtle rounded edge which reduces chain and sprocket wear. This alteration creates a smoother change when the chain is going on and off the chainring and also eliminates the sharp edge that causes chainring wear. SRAM insists that these alterations in design and manufacture will add ‘3 to 4 times more durability to chains, chain rings and cassettes’. When moving up the cassette block to the higher end and creating more taut and extreme angles on the chain, the smoothness of the links makes sure that the wear is reduced, showing tough durability, while retaining smooth and quiet shifting.

Eagle - Chain
The XX1 Eagle chain is a thing of beauty.

A newly designed (and slightly odd looking at first) chainring brings increased chain retention and wear life. Along with this, the new design reduces friction and noise when in application. The most noticeable change has been made in the profile and shape of the thick/thin teeth. By giving the teeth a new shape helps to spread the pressure of the chain onto more teeth positions, thus reducing overall wear. After a certain amount of time on older style chainrings, there would be a hook like shape appear on the front of each of the teeth. This is made where the chain pin repeatedly comes into contact at the same spot. Now though, with the new design and the spread of pressure, this issue has been reduced. The new chainrings will be available in 30, 32, 34, 36 and 38T and will all be backwards compatible with the older 11speed XX1 system.

Eagle Chainring

First riding impressions

When out in Italy, we got two days of unbelievable riding to put Eagle through as much torture as we could. One of the most noticeable things about Eagle was the lack of noise from shifting. In previous systems, this has been rather clunky and running a GX 1×11 system myself, it is something I have noticed before. Riding the new Eagle shows the lengths that SRAM has gone to, to make shifting quieter on the new systems with updated internals in the new shifters and new cables. A larger than previous 14tooth lower jockey wheel in the rear mech, contributes to ‘Eagle’s overall smooth-pedalling feel’. Improved chain retention means almost no chain slap when descending and a scarily quiet shift when putting the drivetrain under pressure on the climbs. Improvements within Eagle are not just down to one piece of the drivetrain, every different piece plays its part. From the material and finish on the cassette sprockets and of course the new chain, everything works as one to produce a drivetrain which is so quiet.

Eagle XO1 - Riding
XO1 coped exceedingly well over a range of trail conditions.

SRAM says it is not built to give you more speeds or more gears, it’s there to provide you a wider riding range for mountain biking

On the first day of the trip we were out on longer travel enduro bikes (running XO1), sessioning a series of trails which were to be used at the weekend’s Super Enduro. This meant a lot of 3-6 minute descents, and quite a few unintentional, but impressive none-the-less collisions concerning the XO1 rear mech and large rocks, with no damage to be seen (panicking stopped). Descents were followed by 20 minute climbs back to the top using loose, rocky trails and fire roads. A range of conditions meant a great way to give the drivetrains some stick, with sudden changes when it came to pedaling out of corners, to dropping into the higher end of the cassette on the climbs. Having the security of the 50T sprocket on the cassette was brilliant, knowing you could drop down one further than usual to a winch like sprocket. The second day was a longer and more consistent XC ride, this time using XX1 Eagle. With lots of ups and downs to make Eagle work hard again, and as hoped, it was incredibly impressive on the climbs, with that 50tooth security and lack of noise when changing under pressure.

Eagle XO1 - Riding_02
Be careful with that shiny new mech and those rocks.

For me, the idea of a 12 speed drivetrain seemed almost unnecessary, with how you can adapt other 1x systems to suit your needs, but after riding Eagle for a good few days in differing conditions and on two completely different bikes, I can really see how well this could work. If you’re an uplift day rider, or a Lycra-clad 60-miles-before-breakfast kind of rider, there are aspects of Eagle XX1 and XO1 that will enhance the way you ride. Whether it be wanting to save weight and improve durability, to the more physical aspects of slugging up the climbs, or smashing down the descents. Whichever way you look at it, Eagle does its proposed job. SRAM says it is not built to give you more speeds or more gears, it’s there to provide you a wider riding range for mountain biking. It’s down to you to put it to the test and make it work.

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According to SRAM, XX1 and XO1 Eagle will be rolling out onto the market from June with MSRP prices stated below:

Eagle Crankset: XX1 – £356.00 // XO1 – £328.00

Eagle Rear Mech: XX1 – £234.00 // XO1 – £185.00

Eagle Trigger Shifter: XX1 – £131.00 // XO1 – £112.00

Eagle Cassette: XG-1299 – £353.00 // XG-1295 – £302.00

Eagle Chain: £50.00 – £71.00

X-Sync Chainring: £79.00

XX1 Complete Group: £1,173.00

XO1 Complete Group: £1,005.00

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