How To: Installing SRAM Eagle AXS Drivetrain [Video]

Words by: Liam Woods

What Tools Do We Need?

Installing SRAM's Eagle AXS wireless electronic drivetrain believe or not is a piece of cake. For tools, you will need a cassette tool, an 8mm hex wrench, a 5mm hex wrench, a 3mm hex wrench, a T25Torxx wrench, a chain breaker, and a T8 Torx wrench. We will also be using a 3-way wrench with a 5mm and T25 on it as well. If you are buying a new SRAM Eagle Rear Derailleur or full SRAM groupset, then it will come with the b-tension tool, but if you do not have that you will also need one of those tools. For shop supplies, we will need some assembly grease and rubber gloves. 

What Makes Up A SRAM Eagle AXS Drivetrain? 

Now let's dive in and take a look at what comes inside the full SRAM XX1 Eagle AXS groupset. On the top layer, we've got the beautiful oil slick XX1 12 speed chain, the non drive side crank arm and crank spindle, the XX1 Eagle AXS controller (shifter), a super slim SRAM multi tool, one eTap/AXS battery pack for the derailleur, the handlebar clamp for the controller, and the battery charger and charging cable. In the 2nd level of the box you'll find the drive side crank arm and chainring, the derailleur, and Eagle AXS b-tension tool. You may be familiar with the red b-tension setting tool that comes with other Eagle derailleurs. The blue b-tension setting tool that comes with Eagle AXS is specific to AXS derailleurs so be sure to use the correct tool. At the very bottom of our box is the crown jewel of SRAM's XX1 Eagle AXS, the full oil slick XG-1299 10 to 50 tooth cassette. Now that we have everything laid out, let's get into it. 

This video/article will be covering how to install a full SRAM Eagle AXS drivetrain, that includes, Cassette, Crankset, Rear Derailleur, Controller, & Chain. We will be going through installation steps so at the end of this you will be able to fully set up and ride your new bike with wireless AXS shifting. Once you have all of your parts that you are installing out of the box and ready to be installed we are ready to go. If you are only installing a AXs upgrade kit with just the Rear Derailleur and Controller then you don't need all these steps and can probably only refer to steps 3, 4, 5, 7, 8 & 9. 

1. Install Cassette (1:37)

Remove your wheel from the bike and apply a layer of grease on to the threads of the freehub body. Set the cassette on the freehub body and tighten it down with your cassette tool. Make sure you start tightening the cassette square with the wheel to avoid cross-threading. Also, make sure you tighten the cassette to a full hard stop, some cassettes, often SRAM GX Eagle, starts to get tight but are not fully threaded on, this can cause the 10t smallest cog to make contact with the frame once installed. 

2. Install Crankset (2:29)

For this particular mountain bike How To, we already have the bottom bracket installed. If you want to get up to speed on installing your bottom bracket, check out our article How To: Install SRAM Eagle DUB Crankset and Bottom Bracket. Apply a thin layer of grease on the crank spindle and slide it through the bottom bracket. With all SRAM DUB bottom brackets, be careful not to knock out the drive side plastic cover when sliding the crank spindle in to place. Use a 8mm hex wrench and tighten the drive side crank arm and chain ring on to the spindle. To remove all of the play from your cranks, turn the preload spacer to snug up the cranks. Be careful not to over tighten that preload spacer and then tighten the pinch bolt using a T8 torx wrench. 

3. Install the Derailleur and Controller (5:00)

Before to toss the derailleur on, be sure to put on some rubber gloves. Oils and grease are bad for your skin! Put a small dab of grease on the threads of the derailleur and thread it on to the derailleur hanger using a 5mm hex wrench. Now we will grab the controller and install the controller on to the handlebar. We will be using a SRAM Matchmaker-X for a nice and tide look on the handlebars. 

4. Install Derailleur Battery (6:40)

The battery comes out of the box with a battery cover on. You can now pull that cover off the battery itself, and then also remove the batter cover from the derailleur. Set the battery into the derailleur and lock it in to place with the latch. 

5. Pair Derailleur and Controller To Each Other (7:00)

Just like pairing your phone with a bluetooth speaker, your SRAM AXS derailleur and controller must be synced together. First press and hold the AXS button next to the battery on the rear derailleur until the small light on the derailleur begins to flash green. Now go up to the AXS controller / shifter and press and hold the button on the underside of the controller until the light on the controller flashes a few times.  The derailleur and controller are now in sync. Now go back to the derailleur and push the AXS button one time to tell the derailleur to stop searching. You should now be able to shift gears using the controller.  The same process would be done if you are also trying to pair your drivetrain and Reverb AXS dropper post, the steps would start at the rear der, and then shifter controller, Reverb controller, Reverb post, and end back at the rear derailleur.

6. Installing the Chain (10:25)

Last but not least, now it's time to install the chain. All SRAM Eagle chains are not directional unlike Shimano chains. Route the chain through your derailleur, cassette, and chain ring keeping in mind that both the chain ring and derailleur pulley wheels use a narrow wide design. Now it's time to cut your chain to length. For a full walk through on installing a chain, check out our How To: Installing A New Chain For Your 1X Drivetrain. Be sure not to cut your chain too short or as you go through your suspension travel, you run the risk of damaging your drivetrain. Set your chain and derailleur in the smallest cog on the cassette and cut the chain at the first available link that pulls the derailleur in to tension. Now install the SRAM chain power link. The power link / quick link is directional so be sure to install it properly. The arrow on the outside of the quick link should point in the same direction that chain travels while pedaling. Make sure that the power link is fully snapped in to place. 

7. Setting the B-Tension: (13:05)

Setting the B-Tension is extremely important for SRAM Eagle 12speed, it’s much more sensitive and needs to be adjusted in sag as well. Once you have your chain on, and rear der shifting, shift into the second to largest cog if you are using the new Sram Eagle B-Tension tool, take a look at the photo below to see the older style and newer style. The good news is that the newer style works for all Sram Eagle Ranges, 10-50t or 10-52t. Once you are in the second to largest cog, you will need to adjust this in sag, so you might need a friend. Once there, place the upper part of the b-tension tool on the 50t or 52t and then rotate the tool and cassette so that the lower part of the tool sits on the upper derailleur pulley. You will notice there is a small window on the B-Tension tool, its a circle with a point in the middle of it. Once the tool is both placed into the largest cog, and then resting on the upper pulley wheel, that point in the small circle should perfectly line up with the upper pulley wheel bolt. Either add or remove tension to the B-Tension bolt to make sure that the upper pulley wheel sits perfectly into that window. 

8. Adjust Limit Screws On The Derailleur (15:25)

Adjusting the limit screws on the derailleur will keep your shifting quick and precise. The limit screws are tucked right underneath the AXS battery pack on the derailleur. The low limit screw which is the right of the two set screws adjusts the low limit or biggest cog. The high limit screw is the left of the two set screws controls the high limit or smallest cog. This may seem a little bit counterintuitive so be sure to follow along in the video above. Start with the high limit screw and adjust the set screw until the chain is spinning smoothly in the smallest cog. Then work your way up to first gear and do the same for the largest cog. Make the limits as tight as possible while still allowing the chain to jump into 1st and 12th gears without any skipping, or jumping around. 

9. Micro Adjustments (18:30)

If you are having trouble getting your chain to shift down in to the smallest cog, this is where the micro adjust comes in to play. Think of the micro adjust feature just like a barrel adjuster on a traditional cable actuated derailleur. To access the micro adjust feature, press and hold the button on the bottom side of the controller and press the controller paddles two clicks at a time in the direction you need the derailleur to adjust. So if you are having trouble getting the chain to drop down into the smallest cog (12th gear), click the downshift paddle when you are in the micro adjust mode.

Be sure to check out the SRAM AXS app on your phone as well for some more handy features!

This article was written / authored by Liam Woods. Liam has been in the bicycle industry for over 10 years as a racer, professional mechanic, service manager and as of late, media and content creator. Liam has ridden thousands of different bikes, ridden countless components, tested endless MTB apparel of all kinds and written reviews on it all. He's a key piece to the Worldwide Cyclery "All Things MTB" content creation puzzle. He also makes consistent appearances on the Worldwide Cyclery YouTube channel and Instagram.

If you're one strange human and would like to read a transcript of the video above, continue reading below!

Hey what's up guys? My name is Liam. I'm the head mechanic at worldwide cyclery and today I'm going to show you guys how to install a new Eagle AXS drivetrain, adjust the limits, pair the shifter and controller, and even use the new b tension tool. Follow along and let's get after it.

All right so as we get to install our eagle AXS drivetrain I have all the parts laid out here. I have an Eagle AXS crankset, i have the new 10 to 52 tooth eagle AXS rear cassette, we have an AXS derailleur, our AXS controller (also known as the shifter), a battery, bottom bracket spacer, shifter bolt, and a chain. So the first thing I'm going to do is throw on the cassette. I'm going to grab my six millimeter and just take this wheel off real quick.

So one nice thing about all these cassettes which if you've had any SRAM in the last couple years is they're super easy to install - needs SRAM xd driver you just throw it on don't really have to line it with any splines. I'm just gonna start tightening it up, there's a little bit of breakaway force needed at first to start tightening it and then keep going and you want to go til you get a really hard stop. There's a torque rating on this but I find that it's like 50 newton meters which is basically as tight as you can go without giving yourself a hernia. So we have our cassette on, I'm also just gonna throw in the crank while I don't have a wheel on the bike because it makes my life easier. There's a little bit of grease provided by SRAM here but I usually just add a little bit more so you can never really have too much grease. you don't want to go in dry ain't that right Reamonn? Yep, good talk. So just a little bit more grease even though there's already grease in there and now I'm going to slide this non-drive side through the bottom bracket over here.

As you come through you want to be super careful that you're lined up because if you're not you'll knock one of those plastic dub spacers out and it's actually kind of a pain to get back in. So then I'm going to put on my dub spacer. On all press-fit bottom brackets you do actually need a spacer so that the crank clears the bottom bracket so I already know it takes a two mil otherwise if you don't know you might have to do some guessing and checking. so eight millimeter allen grab my crank set you definitely want to line these two it's pretty easy on these but i want to make sure. I also just recently did a bottom bracket video so if you want to learn about installing cranks serve some bottom brackets and all that go check out that video. I do english threaded and press fit in that. This yeti takes a press fit bottom bracket for all you press fit haters out there they don't really have any issues. So this also has a torque rating it's about 50 newton meters again i just make it really tight you definitely know when your crank's coming off so make it tight.

One last bit on the crank set is you have to adjust the preload so on the non-drive side there's this preload looks like it's already kind of maxed out so you just want to put it on a little bit and we're going to snug up this bolt right back here I like to use a t8 on this even though it's a 2ml allen i find that a t8 actually bites a little harder and you end up with less stripped out a little two mil allen so you can't really get off so nobody really wants that. 

Next I'm going to install the derailleur. So I'm going to grab the eagle AXS derailleur, again i just like to put a little bit of grease on those threads these don't get a lot of love and they kind of stay on the bike for a long time so five mil allen and we'll just install this make sure your b tension plate is on the back side of the derailleur hanger plate we'll just tighten that up. Again just nice and snug it doesn't have to be crazy. 

Now i'm going to grab the controller, so installing the controller normally we have a sram provided clamp but this customer actually got a wolftooth matchmaker so i'm going to come up here drop the bolt through and just slide it up a little bit like that all right now we'll continue.

Alright so now we have our controller installed, we have our crankset installed, our derailleur installed, we need a battery to be put on the derailleur. Pop this up, i already pre-charged this. If you're installing a brand new AXS kit it does not really come charged so you want to pop this in the charger right away. So this is already charged you can see i got a little green light right when i slid that in. While we have the wheel off we can just pair the derailleur and the shifter. So to pair the derailleur and the shifter it's actually really easy. So what we're going to do is we're first going to come here - we have our AXS button on the derailleur we're going to press and hold the AXS button until we get three flashing lights and then it's going to continue to flash green. Essentially the derailleur is the master. Say we had a reverb AXS on this as well we would start at the derailleur, hit the shifter controller, hit the reverb AXS controller, hit the reverb post, and the pairing back of the derailleur. But since we don't, we're just going to do the derailleur and the controller. So first i'm going to press and hold this, try to get a green flashing button just like that, now i'm going to come up here to the AXS controller and do the same. There's an AXS button right here, press and hold that until it flashes. All right it flashed three times. That means it's in pair mode. I'm gonna end the pairing just by pressing the AXS button once all right so I should be able to shift. Just like that we're paired up.

So this doesn't have any burst modes programmed into it right now so what i'm gonna do once I finish the installation is I want it to shift by holding this button. So right now it only has one mode, what you can do is pull up your AXS app on your mobile device, pair your app with your derailleur, and then you can actually program what amount of shifts you want. You can do one, two, three or unlimited. You can also adjust which way these shift so right now this bottom is my downshift or my up shift I should say to go easier and this is my downshift to go harder, so you can flop the two to where this would make it easier and that would make it harder. They also just released the new AXS paddle which is pretty cool. We don't have one on this but it's gonna make it so you could actually shift from here and here like it's a normal shifter and kind of just  a little bit easier to get used to electronic parts. So now that we have them paired up I'm going to throw the wheel back on the bike. So we'll lock out our cage real quick, tighten up the wheel, all right so now I'm ready to throw on the chain. 

So the way I size the AXS chain and this has changed a little bit with the 10 to 52, because you just want to make sure you have enough chain for when you shift up, is I actually start this in down here and route it around the derailleur pulley, through the derailleur, over the cassette we're going to go over the chain ring as well make sure they're paired up on the correct narrow wide now we're going to overlap down here so once we get down here i'm going to pull it snug. Basically what i'm going to do is we don't have the b tension set yet so just by knowing this i know it's going to need a little bit more b tension which means it's actually going to pull the chain back a little bit.So just to be safe i only want to cut as little as possible because i want the chain to be as long as it needs to be. I'm actually going to cut from this link here because i think i'm going to get more tension on the chain as i adjust the b tension so that's gonna be one two three four five outer links i'm gonna cut grab my chain breaker and count back those five outer lines one two three four five. All right so once we cut those i'm gonna pop my master link back on the correct link and we are going to pull them together. I'm just going to pull this guy to the top up here so I can just pop the chain link together which I just do by holding the back wheel, give a little slap on the cranks, they like it a little rough you know, and now I'm gonna set my b tension.

To set the b tension with a new b tension tool, it's actually a lot different looking than not only the old AXS tool but also the old b tension tool. So here we have the original mechanical eagle AXS eagle and now the new one which actually works for all eagle AXS eagle mechanical eagle AXS 10 to 50 10 to 52 tooth. This works for everything but you do have to use it differently than you use these. So you used to go into the easiest largest cog on this one you're actually going to second the largest on this so as you shift up, yeah you can already hear that that's touching there so i'm gonna add a couple turns just so i can get up there without too much scraping. All right so we're gonna live in this cog to do our adjustment so you really want to do this adjustment under sag but when the bike's being built brand new i just do it in the stand and then later on i adjust it with the rider um under sag because under sag this tends to move a little bit. So you want to make sure it's really close as eagle and 12 speed in general are a little bit more sensitive so you grab this tool put it on here and you just want to push it on and it'll stop at the correct spot for the 52 or the 50 tooth we're just going to rotate this down until it touches this pulley wheel so what we're going to look for is for this upper derailleur bolt derailleur pulley bolt to get in the middle of our window here with a point so what i'm gonna have to do is add the tension until we get there and as you move it just kind of make sure it's still making contact. All right so we're right in the middle there and like I said you actually want to do this adjustment under sag but since I don't have the rider here and I'm by myself I'm just going to do it in the stand to set it up and then I readjust it a little bit later. 

So now we should be all good with our b tension, and the last thing we're going to do is adjust our limits. So carefully shift into the first gear. There we go, and i'm just gonna roll in these until I get some derailleur movement. These are actually opposite of what you'd think. This is going to be your low limit this is going to be your high limit and another easy way to remember which is low and high think of this as a pyramid this is gonna sit at the bottom that's gonna sit at the top this is the low spot of pyramid that's the high spot of the pyramid. all right so i just got a little bit of movement by tightening that guy in so i want it tight enough to where i'm not gonna shift over into the wheel especially on this nice wheel, but i don't want it too tight so i can't shift into the gear so that looks to be good right there i'm gonna try a quarter turn more and you can kind of hear now it's fighting itself so that was too much so i'm going to back it off a quarter turn. So it's still fighting itself a little bit so I'm going to give it one more quarter turn. That's a bit better. Alright now i'm going to do my high limits. Same thing, I'm just going to start tightening this guy and try to get some movement out of the derailleur. Once i see some movement right there so you see that it might be hard to see on camera but a little bit of movement so now i'm gonna just start pedaling it, now shift it up back it off full turn. Now it's finding itself there we go so once it falls in it's usually good but we're just going to double check it and with AXS it's hard to to manually check that so normally with mechanical we can just take some tension off the cable and shift with our hands on this and see if it goes over under it's kind of hard to check that one AXS so until then i just go as tight as i can and back it off with a quick turn and now we're just going to do our small little adjustments and make sure it's indexing properly between all these gears so i'm gonna run through it a little bit see if it's slow jumping up or coming down it actually looks like it's really good going up if not a touch fast as i'm coming down looks to be a touch slow so i'm just gonna adjust it one uh one little click so it drops down faster on a mechanical that would be taking tension off on the AXS you just want to make sure you're going to adjust the shifter in the way you want it to drop or move faster so i want it to drop down faster which means i want to adjust this guy here one click. Once it's in adjustment mode to get it in adjustment mode you come down to the AXS button, press and hold until it goes green one tap until it goes off comes back on once it's on it's been adjusted so our adjustment's been made already.

Still seems a touch slow dropping and it's going up fine so i'm going to do one more of those, so one more now it's dropping pretty even as it goes up.

And there we are, our AXS is installed, we're adjusted, our derailleur is adjusted, limit set, b tension set properly, once the rider gets here i'll need to do it under sag, but it's good to go in the stand and we're all paired up. If you wanna make any of those last adjustments uh like get the three bursts which i'm about to do or alternate which way the shift uh do it on the app other than that you're good to go ride and i enjoy your wireless shifting because it's a treat and it's just very nicely.

All right, hopefully that was useful and you can now install Eagle AXS on your own. Let us know in the comments what tech tips you want to see next and if you want to watch more videos like this, click the link at the end of the video. See you in the next one!