June 25, 2021

Sram GX Eagle AXS Review

Electric Dreams – 3 Months Living with SRAM GX EAGLE AXS

GX Eagle is SRAM’s workhorse groupset. And if you’ve owned a bike fitted with it, most likely you’ve had a great experience. It works! It’s light enough, durable enough and offers enough performance to make upgrading to its more expensive stablemates more a matter of desire, rather than need. Are the weight savings and performance gains with XX1 or X01 noticeable enough for the premium you’ll pay? My personal jury is out on that. Modern derailleur shifting is now good enough that throwing dollars at ultra-premium shifting may be a classic case of a buying a better mousetrap for diminishing returns.


But when SRAM launched AXS (say it “access”) a couple of years ago, its wireless, electronic shifting promised something as yet unseen – the unflinching reliability of your very own robot derailleur, working away, shift after shift, whatever the weather, until the battery runs out…


The price point of XX1 AXS has probably prevented most riders from experiencing whether that robot mousetrap really is better – the derailleur alone costing around $1,500. If you’ve been riding for a while, you’ve probably had an incident in which you’ve broken your derailleur too, which might make you a little wary of bolting a grand and a half of AXS to your much-loved crash test sled.


But in March this year, SRAM announced the arrival of AXS technology on its GX group. The trickle down of the technology has resulted in a full group or an upgrade kit containing derailleur, controller, battery and changer at a not insubstantial, but certainly not eyewatering price of $1,150. I’ve spent the last quarter giving it a proper shakedown, shifting as badly as I can, getting it dirty, spraying it with hosepipes and generally mistreating it to see if it really can offer the everyday mountain biker an extraordinary experience.


What’s in the box?

For your money, the AXS GX upgrade kit includes everything you need to start shifting wirelessly – a derailleur, controller, MatchMaker and clamp, battery, charger, cable, battery cover and a special plastic chain gap template to make sure you get everything set up right. All of the components are compatible with other SRAM Eagle components and the wireless controller and derailleur are cross compatible with other AXS parts.


The Derailleur

The derailleur is designed to be compatible with SRAM’s 50 and 52 tooth cassettes. Inside it, there’s an electronic servo-motor and gearbox that make the derailleur move whilst emitting a cool robot noise whilst they do it. There are not one, but two clutches. The first is your regular clutch for chain retention, but the second is something called the “Overload Clutch”. This is a smart function that’s designed to protect the mechanism by disengaging the electronics in the event of an impact – shark attacks, trees stumps, involuntary dismounts and the like. I gave it an exploratory whack with a rubber mallet to see what would happen – and the derailleur took it on the chin before moving smartly back into place, ready to go.

Other features include a battery/operation LED and a neat plastic clip-on battery cover that gives a little extra security to the battery in rough terrain. The battery itself clips securely to the derailleur and weighs around 25 grams. SRAM reckon you’ll get around 20 hours of riding out of each charge.

The whole unit weighs in at 460 grams, including the battery and cover. That’s a little heavier than its more expensive XX1 cousin which weighs 374 grams, but XX1 doesn’t feature the battery cover. Most of that 86 gram weight difference comes from the steel cage and hardware that the GX unit uses as opposed to the carbon and titanium found on XX1. For the record, a regular GX derailleur weighs around 290 grams.


The Controller

With no need for a cable to pull, the control unit is a little different to a regular shifter. Instead of two levers, there’s a single large paddle. Its curved design is intended to allow your thumb to rest in the cradle, from where moving it up or down will result in a shift. Using the AXS app, you can program the controller to work a couple of ways. I set it up so a push on the lower part of the paddle shifted up the cassette and the upper part shifted down. You can also tap part of the paddle on the front side of the bar with your finger to get a shift down the block, Shimano-style (Or an up shift, if you set it up the other way).

The app also allows you to program multiple shifts. Holding the paddle can shift one, two or three cogs across the block, depending on your preference.

The controller is powered by a CR2032 battery that’s available from any hardware store and connects to the derailleur via SRAM’s proprietary encrypted wireless network.

You can mount the unit with its own clamp, or using SRAM’s MatchMaker fittings. It weighs 70 grams, which is exactly the same as the XX1 version.

If you’re a real weight-weenie then you’ll probably want to know that the total weight of the cable actuated GX Eagle derailleur, shifter, cable and housing I replaced was 485 grams. That’s a 45 gram difference between the two.



With no cables to feed through or zip-tie to your frame, fitting GX AXS to your bike isn’t much more difficult than attaching a set of lock-on grips. In fact it took marginally longer to get up and riding than it did to remove the old parts and cable housing.

Simply bolt the derailleur to your hanger (make sure it’s straight – a bent hanger is about the only thing that can out-fox the machine), feed the chain through and then use the template that’s included in the box to make sure everything’s in the right spot. Then pair the two components using the magic of wireless by pressing the button on the derailleur parallelogram and the one on the base of the controller. Having set the limit screws, there’s no cable to tension. Fine tuning can be done using the trim function that allows you to make micro adjustments from the controller. Align the pulley with the teeth of the second highest gear and you’re done! SRAM’s video is a useful how-to you can watch whilst you do it if you like.


The AXS App

This free app is available for Android or iOS. It allows you to customise the functions of the components including the way the paddle shifter works and the multi-shift option. It’s also a handy way to assess the level of battery charge.


Out on the trail

So now you have a nice tidy cockpit, with one less cable hanging out there, but does it work?

Yes. Emphatically. It’s very, very good. But before we get into the detail of how well it works, it’s worth considering how we interact with cable operated derailleurs, because that’s not as simple as you might think.

Anyone who’s been riding for a couple of years knows that when you change gear with a cable, you don’t just click and the gears change. It’s not that automatic, there’s a lot of subtle feely things happening there. You know you need to make certain shifts with a little care, so you push the lever slowly, gently, easing the chain up the block. You know that in certain gears, you need to push just a little past the click, to give the chain that little more incentive to find the ramps and go. There’s more skill to those thumb movements than we give credit for.

But the AXS paddle is effectively just two buttons. With no wheels, springs and ratchets inside the shifter and no cable to pull, the action of the paddle is incredibly light compared with cable shifting. This means that all that muscle memory in your thumb has been superseded. Simply push the lever a couple of millimeters in either direction and you’ll feel a positive “click” followed almost instantaneously by the “chirrup” of the derailleur and you’ve changed gear. Simple as that. Keep the pressure on and you’ll shift the additional gears you’ve programmed it to. Press it again and the same thing happens.

Is it faster than a regular derailleur? No. But it’s certainly not slower. Because you can only shift across a maximum of three cogs at a time, it might take you slightly longer to cross the whole cassette – but that might also save you from snapping your chain…

The shifting is quite a remarkable sensation the first time you use it, but what’s more remarkable is that whatever, wherever and however you’re riding, it just keeps on working. Every. Single. Shift. Mud doesn’t phase it. Rain doesn’t phase it. Not washing your bike doesn’t phase it. From the very first shift until I started writing this 3 month review, each gear change has been as good as the last, with absolutely no deterioration in performance at all. There’s no cable to stretch or get contaminated, no housing to be forced around too-tight curves and no barrel adjuster to fiddle with. Just immaculate shift after immaculate shift.

I can’t say that it’s smoother than any other SRAM kit that I’ve used, but it’s certainly on par with a well set up, top-end group and I‘ve got no complaints whatsoever about its performance. Tune-ups are a now a thing of the past. The only thing that will stop the machine is a bent derailleur hanger or a flat battery.

Speaking of which, I found SRAM’s estimate of 20 hours of riding time from each battery charge to be approximately what I experienced in practice. The battery is easy to remove and the charging unit supplied has a USB cable so you can plug it in to just about any power source you might need to. Charging the battery takes about an hour and you can check whether it’s charged using the coloured LED on the derailleur or via the smartphone app. There’s a power saving mode that automatically engages when the bike is stationary, bnut moving the bike or clicking the shifter wakes everything back up again.

Did I run out of power? Yes. Once. That was because I didn’t check the battery before I headed out. It’s a mistake I won’t make again as once you’re stuck in that gear, you’re stuck in that gear. Yes, it’s one more thing to think about in your pre-ride checks (assuming you do them), but once you’re used to it, it’s no drama. SRAM supplied two batteries for the test and I would recommend purchasing a spare so you always have one charged up and ready to go. In practice, I haven’t had an issue since learning the hard way, but it’s reassuring to have that option.

The biggest difference I found with AXS was using the control unit. Your thumb sits in the scoop of the paddle and you move it up or down to shift. This isn’t quite the same as the push-push action of a regular lever and it took me a while to get the unit in the right place on the bar. To begin with, my thumb was catching the edge of the paddle more often than it was sitting comfortably in the scoop, but the choice of a separate clamp or MatchMaker mount means there’s plenty of adjustment available. After a little experimentation and retraining of my thumb, I’m very happy with the set up. For those who really don’t like the paddle, SRAM offers an alternative shaped lever as an aftermarket add-on. It’s designed to mimic a regular paddle more closely.



Is this the future? Having started the test period feeling as though wireless shifting might be a bit of a gimmick, I have to say I’m pretty impressed. This has been the most reliable gear changing experience I’ve had to-date. Not once have I had to adjust anything. It simply keeps on working. Consequently, the answer is a firm “yes”. Sure, it’s a better mousetrap, but it’s a more reliable mousetrap that’s a pleasure to use.

Should you go out and buy one? At over $1,100 it’s certainly not inexpensive, but if you’re building a new bike, your current 12 speed SRAM derailleur is showing signs of wear, or is in pieces at the side of the trail then go for it. I’d even recommend “downgrading” from X01. Unless you’re counting all the grams, you’ll appreciate the robotic efficiency of GX Eagle AXS and you’re unlikely to notice any drop in performance. Plus you’ll never have to touch a cable barrel adjuster again.

In short, GX Eagle AXS is simple to set up, efficient in use and incredibly reliable. The only downsides are the price point and the need to check your battery before you head out. All-up, I’m all in.

Rich Birkby