SRAM's new wireless mountain bike drivetrain has 12 gears, uses two clutches, can be paired with the new Reverb AXS dropper post and will cost £1,900 / $1,900 / €2,000 for the X01 version.
For those that have been following the cross-country World Cup or visited any kind of bike related website, then SRAM’s new electronic mountain bike drivetrain is no big secret.
We first saw it aboard Nino Schurter’s bike when the World Cup circus visited Stellenbosch, South Africa in early 2018, and although it’s been in the wild for some time now, details have remained rather thin on the ground.
After five years in the making though, it’s now ready to be released to the public. So I disappeared off to the rock-riddled trails of Tucson, Arizona to find out more about SRAM’s new Eagle AXS wireless drivetrain and do my best to dodge the cacti.
SRAM Eagle AXS wireless drivetrain
Electronic shifting is fairly new in mountain biking. While it’s considered the norm on high-end road bikes, for those of us that mess around in the mud it wasn’t until Shimano introduced XTR Di2 to the public, back in 2014, that mountain bikers really started to pay attention to it.
While Di2 is certainly pretty slick and packed full of tidy features, it still relies on small wires to connect the shifters to the derailleurs and battery, which itself needs to be stowed somewhere on or in the frame. SRAM’s new XX1/X01 Eagle AXS (pronounced ‘access’) drivetrain is, as I’ve already mentioned, wireless.
Naturally, this removes the hassle of threading gear cables internally through the frame (if they’re internally routed) or worrying about cable stretch and wear, along with decluttering the cockpit and doing away with any kind of cable rattle (for the most part, at least), which is no bad thing.
The shifter and rear derailleur simply talk to one another within their own wireless network in order to make the required gear shifts. It’s all very impressive.
SRAM Eagle AXS Bluetooth connection and AXS smartphone app
Before we get into too much detail around the all-new Eagle AXS shifter and derailleur, lets first talk about how these two components interact with one another and you, the rider.
The AXS components include the new Reverb AXS post, which you can read about here, and are connected with SRAM’s proprietary encrypted wireless network.
Once you’ve paired your shifter and derailleur (more on that in a minute) you’re more or less ready to ride. Should you want to alter how the shifter works though (changing what any of the three buttons do), then you can via the AXS smartphone app which connects to the components via Bluetooth.
The AXS app is very intuitive to use and allows you to alter things such as button function, the multi-shift function and check on features including battery life as well as mileage and other ride data.
If you’re worried about having someone else tinker with your components via the app, SRAM has ensured that you need to be in physical contact with the bike in order to sync your phone to each component.
Once the app is opened, it’ll scan for components, just as your phone would when looking for other Bluetooth devices.
To sync your shifter and derailleur with your phone, you’ll need to be pressing that particular component’s AXS button while its connecting. Of course, you could potentially do this and connect to other people’s components, but you’d need to be with their bike while you’re doing it, which will likely be noticed. Should someone manage it, at worst they’ll meddle with your shifter functions, but that’s about it.
SRAM was quick to point out that you don’t need the app to use its Eagle AXS drivetrain, which is totally true, but it’s worth noting that all firmware updates will come via the app, so it’s helpful to keep an eye on.
All AXS components also feature ANT+ should you want to keep tabs on what’s going on via your GPS unit.
SRAM Eagle AXS shifter information
Take a closer look at the shifter and it’s clear to see that this isn’t quite like any other traditional mountain bike shifter. While Shimano’s XTR and XT Di2 shifter employs a modified twin-paddle arrangement, it seems SRAM was keen to use something a little different.
In the words of Chris Hilton, SRAM MTB product manager: “You don’t mimic a mechanical system with an electronic system. You build an electronic system to do things that a mechanical system can’t do.”
As a result, the AXS shifter doesn’t use what we’d consider two traditional paddles to change gear. Instead, the single paddle on the front of the shifter — which rocks on a central pivot — sits over two buttons and lets you shift up and down the gears by pushing on the top or bottom half of the paddle. There’s very little in the way of throw when pushing the paddle compared to a mechanical system which leads to an incredibly light actuation.
SRAM has then included a third button on the back of the shifter which can easily be actuated with your index finger, which has been very popular with Schurter, apparently, who’s said to use it constantly when sprinting. The front two buttons require a different amount of force to depress them, giving them each a unique feel.
As you might imagine, settling on the paddle shape didn’t happen easily. According to SRAM, it went through more than 100 variants of the paddle, even trying two single buttons as well as a shifter that uses a twin paddle design, not a million miles away from that of Shimano’s Di2, before deciding upon what you see today.
SRAM was keen to point out that the paddle can easily be modified with something like Sugru, should you want to adapt it further. I did ask if SRAM would consider offering different variants to be sold as part of the entire drivetrain or as an aftermarket product and it seems that it’s something the brand is certainly considering.
If you’re keen on altering which button does what, it’s straight forward enough thanks to the AXS app. You can even have your AXS gear shifter control your Reverb AXS post and your Reverb AXS remote control either your up or down shifts.
The easy to understand and intuitive user interface means even technophobes should be capable of getting their shifters customised to their liking without too much fuss.
While the battery on the rear derailleur is clearly visible, the shifter also contains one. This time it’s in the shape of a CR2032, which is roughly the size of a penny and should last a couple of years before it needs to be replaced.
SRAM Eagle AXS derailleur details
The new Eagle AXS derailleur may look quite similar to a regular Eagle unit with a battery attached, but, even without the addition of the battery, motor and gearbox, there are a number of other design features that make it stand out from what’s currently available.
First and foremost is the 25g removable battery (which will work and can be swapped with a Reverb AXS battery should it be running low on juice), gearbox and motor.
The battery can be whipped off the derailleur easily because it’s held in place with just a single clip and SRAM claims it takes just an hour to charge, delivering around 25 hours of ride time.
While SRAM explored using the motor that already exists for its eTAP derailleur, more shifting torque was required for the rigours of mountain biking, and the unit it's settled on operates at around 80,000RPM.
SRAM Eagle AXS derailleur Overload Clutch
It’s all well and good having all this tech dangling off the back of your bike, but as we’ve all experienced in the past, it’s not hard to whack your derailleur, sending your shifting into disarray or tearing it off entirely. The Eagle AXS derailleur features two clutches to help prevent this.
The first is the standard Type 3 Roller Bearing clutch, which is used to keep your chain in check and stop it from flapping around and falling off the chainring.
The second is arguably the more important in this case. Dubbed the Overload Clutch, it’s designed to disengage the shift motor should you whack your derailleur into a rock forcing it in towards the wheel or, if some kind of trail debris should get wedged into your wheel, forcing it outwards.
On impact, the Overload Clutch allows the derailleur to move on impact without causing damage to the gearbox or motor before returning to the last known shift location. It’ll also help preserve your gear hanger too, which is useful.
While this may not be as robust as a full-on gearbox design which removes the rear derailleur from the equation (there still seems to be few gearbox bikes being made, though the numbers are creeping up), it’s certainly a step in the right direction when it comes to preserving something as expensive as this.
Aside from that, there’s a host of other changes. The new Eagle AXS mech has been moved around the bike further, improving chain wrap on the cassette. This in turns helps to dissipate chain load which should help improve chain and cassette wear, as well as keep things feeling more precise for longer.
It also uses a slightly shorter cage (XX1 uses a carbon cage, X01 uses an alloy cage) which increases ground clearance by 10mm compared to the standard Eagle derailleur.
SRAM Eagle AXS charging time and battery life
As we’ve already mentioned, the battery in the shifter (a CR2032) should last you a couple of years, while the removable battery on the rear derailleur will provide around 25 hours ride time, according to SRAM.
That’s because the AXS system will go to ‘sleep’ when not in use, only waking up when the bike is moved (via accelerometers) or the shifter pushed.
To check battery life, you can, of course, use the AXS app on your phone. Alternatively, you can push the AXS button on the derailleur and check the colour of the LED. If it’s green, the battery is fully or close to being fully charged.
A red light indicates that the battery is half or close to half charged while a flashing red light means it’s time to plug it in to charge and it should be back to 100 percent in about an hour.
How to set up SRAM Eagle AXS
One of the major downsides for me with Shimano’s system was the complication of routing the wires and stowing the battery. It can be fiddly and, in my experience, travelling with the bike or even pulling it out of a badly packed garage can dislodge a wire accidentally, which I worried about constantly.
It’s far simpler with the Eagle AXS drivetrain. You can bolt the derailleur and shifter in place then pair them by simultaneously pushing the AXS buttons on each component.
Like a standard Eagle derailleur, you’ll need to adjust the b-tension screw using the guide provided, known as the AXS B-Gap tool, but it’s best to leave the other limit screws for now. You’ll then need to ensure the shifting is indexed by trimming the mech into position, using the AXS button on the mech and toggling the shifter in the appropriate direction.
At that point, it’s time to screw the limit screws in until they’re close to but not in contact with the stops at either extreme.
How waterproof is SRAM Eagle AXS?
Mountain biking is by no means a fair-weather sport, especially in countries like the UK. SRAM is all too aware of this and has ensured the new AXS system will stand up to all the mud, rain and puddle splashes we riders can throw at it.
It’s certified to the IP69K standard which means it should handle pretty much everything.
Naturally, it’s worth being mindful if you’re a regular power washer. Apparently Schurter had one issue with a faulty seal after numerous power washes which allowed water ingress.
This hasn’t happened since though, but SRAM was quick to point out it’s worth being careful around the derailleur just as you would around hub, pivot and fork seals if you do want to blast your bike.
SRAM Eagle AXS X01 and XX1 models
SRAM is launching the Eagle AXS drivetrain as two complete systems: XX1 and X01. These include the shifter, derailleur, cranks, chainring, chain and 10-50t cassette.
The Eagle AXS shifter and derailleur will work with other Eagle cranks, chainrings and cassettes though, if you are looking to save a bit should you wish to upgrade.
That’s because the cranks are essentially identical to what’s already on offer and use SRAM's DUB technology. It’s the same story for the chain, chainrings and cassette, though chainring and cassette colour may differ slightly.
The current systems on offer vary a little in intention. XX1 Eagle AXS is aimed more at cross-country riders and races, and uses titanium hardware, a carbon derailleur cage and comes in SRAM’s ‘rainbow’ colourway. X01 Eagle AXS is a little more robust and designed for trail and enduro riders, using stainless steel hardware and an alloy derailleur cage.
Gear range is the same as the current Eagle system, at 500 percent.
SRAM Eagle AXS X01 and XX1 prices
Let’s start with the weight. SRAM claims that the XX1 Eagle AXS system is actually 5g less than its mechanical counterpart which is pretty impressive.
Naturally, it’s the price that everyone wants to find out and as you can imagine, this sort of new tech doesn’t come cheap.
The XX1 Eagle AXS drivetrain (that’s shifter, derailleur, chain, cassette, cranks and chainring) will set you back £1,950 / $2,000 / €2,100 while the X01 Eagle AXS is £1,900 / £1,900 / €2,000.
SRAM Eagle AXS X01 ride impressions
I’ll admit, I’m somewhat of a technophobe when it comes to adding electronics to my bike. I’m also rather cynical when it comes to this sort of thing. Will it really make my life on the bike that much better?
Riding for me is about avoiding all of that extra complexity and the last thing I’m looking for is additional hassle when I’m out on the trail. I must confess though, AXS seems (bearing in mind I only rode it for a few days) really simple and easy to use and didn’t take anything away from the ride experience.
After a couple of hours on the trail, I made a slight change to the shifter position on the bar, rolling it under the bar a little more to better sync with my thumb. Generally, I normally move it the other way so I can access the thumb paddle more easily when out of the saddle, but the opposite was needed in this case.
With the shifter in what felt like a better position for me, I didn’t feel any need to alter the shifter function using the app, though in hindsight I probably should have limited the multi-shift function.
That’s mainly down to how rough and awkward the trails we were riding were, requiring up and downshifts in rapid succession when in and out of the saddle. At times, due to the light action of the shifter and lack of throw, I over-shifted.
While I adapted to the feel of the shifter — something that after 20 odd years of riding a conventional shifter takes a good few hours to get used to — and didn’t make as many accidental shifts, it's nice to know I can tweak this in the app.
For me, it was more the lack of throw from the shifter paddle that was the hardest thing to get used to. While on the one hand it does mean shifting takes less effort and movement, it didn’t feel easy to undo all those years of using a regular twin paddle shifter. I could certainly see why Schurter and other racers might gravitate towards it though as gear changes are rapid.
I didn’t know the Tucson trails, so there were a number of times when I’d round a turn at speed, only to be faced with an awkward, nadgery climb through a boulder field. It was in these situations that any kind of shifting finesse went out the window and I would hammer the shifter while pushing the pedals to find an easier gear.
Fortunately, even under power, shifting remained accurate. Even the effort required to shift up into the biggest 50t sprocket seemed minimal, with a smooth shift and next to no noise.
Of course, there are other benefits to the wireless system. The lack of cable clatter was noticeable straight away. I realise this is possible with a well set up bike, but imagine not having to take the time to do that?
As for the Overload Clutch safety mechanism on the derailleur, I can confirm that it works. Okay, I only belted the derailleur once, but it was one hell of a clout and got me thinking that my ride was over.
I’d cut inside on a tight, steep turn and clanged a rock in the process. I heard the sound of metal on stone and cringed. Within seconds there was a mechanical whirr while the mech re-set itself and shifting carried on unaffected. I was impressed.
Overall, it’s the price that will put a lot of people off, especially with how well the current crop of mechanical systems work, and how cheap they are to maintain.
The AXS system does seem to work really well, though, and manages to add an air of simplicity to proceedings which I for one really appreciate. There’s still a rear derailleur hanging from the back of your bike, but it’s good to see SRAM has had the foresight to add some safety measures in there to hopefully save it from total destruction.
Ditching the cables also means way less hassle with internal routing for both the rider and frame designer, which is an exciting prospect.
Whether or not we’ll see this trickle down to cheaper drivetrains is a bit of an unknown right now, especially with most of the extra cost sitting with the electrical componentry, which is something SRAM isn’t likely to want to compromise on by using cheaper parts. Only time will tell.
It’s important to bear in mind that my time on the new drivetrain was seriously limited, so my experience is but a snapshot. I can’t comment on long-term durability or any of the potential problems associated with mixing electronics, mud and water. When test samples arrive though, I’ll be sure to keep you all updated later in the year.
SRAM has gone to town and launched a road bike specific 12-speed wireless groupset at the same time as their mountain bike kit. Read about the new Red eTap AXS groupset here.