I’m a bit reluctant to give out Singletrack Recommended awards to drivetrains. Because really when it boils down to it, all they do is shift gears. It’s not as if they control suspension, or keep you stuck to the trail, or finely moderate your descending speed.
At the risk of sounding like the voiceover for an SUV commercial though, SRAM GX Eagle is more than a drivetrain. It’s a lifesty…just kidding. It is just a drivetrain, albeit one that works very well. It shifts through its 12 gears with wonderful efficiency and minimal fuss, and it’s super tough. Plus, it’s nearly a third of the price of XX1.
It isn’t just about adding a 12th gear though. What that 12th gear does, with its 500% range, is almost eliminate the need for a front derailleur. And if you don’t need a front derailleur, frame designers get excited. Tyre and mud clearance can be increased. The BB area can be made stiffer, and chainstay length can be made shorter. On full suspension bikes, the main pivot can be built wider and stronger, and its location can be optimised around a single chainring.
Of course XX1 made all of this achievable in 2016, but it’s been GX Eagle that has made the technology truly accessible. For frame designers and product managers considering a whole range of spec levels for one model of bike, the decision to eliminate the front mech has become that much easier. Indeed SRAM’s decision to skip X1 and go straight to GX for its latest Eagle drivetrain proved to be the winning move of 2017. For 2018, it’s absolutely everywhere – and for good reason.
Since its release, I’ve put eight months of riding on our longterm test drivetrain. In addition to that, I’ve ridden half a dozen test bikes fitted with GX Eagle, so I’ve become pretty familiar with its performance, setup quirks and durability.
With that in mind, lets take a closer look at the components that make up this entry-level 12-speed drivetrain, and how they’ve fared over time.
Much of GX Eagle’s price comes down to the crankset. Instead of fancy hollow carbon arms like on XX1, the GX Eagle arms are solid-forged from 7000-series alloy. As such, weight has increased by about three Wispas to 629g (32T chainring, no BB). Regardless, the girder-like arms are hugely stiff and tough. Not having to worry about gouging carbon cranks into granite is also nice.
Our test cranks came with a regular 24mm steel GXP spindle, and durability with SRAM’s own GXP threaded bottom bracket has been fine. The GX Eagle cranks have also been available in a BB30 version, though as you’ll likely have already read, SRAM has just announced its new DUB crank axle standard. Using a 28.9mm diameter alloy spindle and four different accompanying bottom brackets, the theory behind DUB is to provide a stiff and light crankset, but with greater compatibility with more frame standards. Expect to see DUB showing up on 2019 model year bikes, as in time, SRAM expects to replace both GXP & BB30 entirely.
The X-Sync 2 chainring is easily one of the standout performers for GX Eagle. It’s smoother than previous X-Sync chainrings, but it’s the drastic improvement in durability and chain retention that puts it well above other narrow-wide chainrings. I am still yet to drop a chain with any of the half dozen GX Eagle groupsets I’ve tested. This X-Sync 2 chainring is also compatible with other 11 and 12-speed drivetrains, making it an excellent standalone upgrade if you’re dropping chains a lot with your existing setup.
Shift feel is characteristically SRAM, with chunky downshifts and a short, punchy upshift. The forged alloy lever isn’t adjustable like it is on XX1, and the paddle shape is a little pointier on the thumb. And while I’m nit-picking, I do miss the double-upshift that Shimano shifters offer. Regardless, the GX shifter works, and it integrates cleanly with SRAM brakes via the MatchMaker X clamp. A grip shift option is also available.
Similarly, the rear mech omits some of the exotic materials of XX1 while achieving much of the same performance. There’s a die-cast alloy construction and a steel spring (rather than the forged alloy and titanium spring found on XX1), but otherwise it still has the same jockey wheels and the same Type 3 clutch. Clutch tension is smooth but firm, with none of the knocking issues that plagued earlier generation clutches. And the Cage Lock button is still my favourite aid for taking the rear wheel off the bike.
Despite sticking out much further than Shimano’s Shadow Plus design, the GX Eagle mech has shrugged off plenty of close encounters with rocks, and is still shifting reliably. It is sensitive to setup though, so make sure you get that B-tension right and it’ll do as told.
One thing to be careful of is when removing the rear derailleur. If you undo the main mounting bolt without the Cage Lock engaged, there’s enough friction that it’s possible for the B-tension plate to stick, and the circlip that holds the main bolt in place can ping off. That happened to me in the workshop late one night while packing a bike for a riding trip over to Finale Ligure. I managed to find the circlip, but I couldn’t get it back on as it’s a royal pain in the arse. The derailleur will fit fine without the circlip, but it means the mounting bolt can fall out completely. Now if I pull the derailleur off the hanger, I thread a cable tie through the main bolt to keep it safe.
Aside from the cranks, the other key cost-saving area is the GX cassette. The 50t dinner plate is machined from alloy, and it’s pinned together with the other 11 stamped steel sprockets via no fewer than 123 stainless steel pins. This adds a bit of weight over XX1 (448g vs 360g), but it is literally less than half the cost. The sprocket sizes and 500% ratio is the same, and while the shifting isn’t quite as smooth, it’s very close, and it’s a sizable improvement on GX 11-speed.
Teeth wear has been impressive. Yes it’s still a £170 cassette, but in our experience, durability on these is (like with XX1 and X01 cassettes) exceptionally good. And if you don’t need to replace cassettes as often, that price is a whole lot easier to swallow. Much of this durability also comes down to the chain, which is – unbelievably – still yet to pass 0.25 on the chain wear gauge. The super-narrow chain doesn’t get the hollow chrome-hardened pins as the XX1 chain, but it has proven to be just as tough. And it’s £26 too.
SRAM GX Eagle may have only added one more gear over its 1×11 predecessor, but it’s improved in almost every way. It has more range so you can run a bigger chainring for more top-end speed, or in my case, run the same size ring and enjoy a new lower climbing gear. It’s smoother overall compared to GX 11-speed, but it’s the leap in durability and chain retention that makes it a standout groupset for the money.
|Product:||GX Eagle 1x12 Drivetrain|
|Price:||£432 (complete drivetrain), £179 (cassette), £26 (chain), £112 (cranks), £98 (derailleur) & £31 (shifter)|
|Tested:||by Wil Barrett for 8 months|