At my wits end with the SRAM AXS Eagle 1x12 derailleur

[Black Hawk Down]

I have a Q45 that I built up from a frame. I have been trying for several months to get the SRAM AXS Eagle GX derailleur working to no avail. I have a 1x12 10-52t cassette and a 36t chain ring. My problem is that I have to double shift the first three (1, 2, 3) gears when moving from low to high, and the last three gears (12, 11, 10) when moving from high to low. Double shifting means I have to shift twice, then shift back once. I've gone through 3 derailleurs, two through warranty return and one by purchasing on Amazon, and they all work the same. I tried optimizing the chain length, but the only length that works at all is when you overlap the chain over the largest cassette gear and the chain ring, and the overlap is 2 inner and 2 outer chain links, which is the SRAM recommended method. I tried removing one link and adding one link, but it would not work at all in those cases. For the correct chain length, I have to completely back out the b-screw, and even so, the derailleur cog is about 20 mm from the a tooth on first gear when the chain is on second gear. According to SRAM it should be 15 mm for Eagle. No way that can happen no matter what I do. There's only one thing that I have not yet tried and that's to check the angle of the derailleur hanger to see if it's bent. I ordered a tool, but it won't arrive for a week or so. I don't have much hope that that will solve it as it seems if the hanger was bent, it would bias in one direction. I need a bias in one direction for the low gears and the opposite direction for the high gears. It's possible that the Q45 hanger is wrongly placed for the SRAM Eagle derailleur.

I'm ready to sell everything on eBay and start again with Shimano DI2. I have that working well on my V20. It also worked well on my S40. Thought I would go a different direction on the Q45. So far, it's a bust. I'm beginning to think that the Q45 will not work with SRAM Eagle. Any ideas on what else I can do would be welcome. Thanks,
Bill

 

[xtalbike]

Is it a SRAM AXS cassette? My experience with AXS on the V20 (so not Eagle) was that I had to go with AXS chain, chainrings, and cassette for it to be happy.

 

[Frito Bandito]

Is it a SRAM AXS cassette? My experience with AXS on the V20 (so not Eagle) was that I had to go with AXS chain, chainrings, and cassette for it to be happy.

I have Force AXS RD with a Shimano Ultegra cassette and have heard the same thing. Match the chain manufacturer to the cassette no matter what mullet setup you run. Black Hawk, could it be something in the app settings?

 

[cpml123]

That's odd. I have 2021 Q45 (current generation). I converted to AXS. I use Eagle 10/52 cassette, chain and derailleur. I didn't change the front setup though. I kept the stock 42 ring and crank. Because the chain ring has 2 possible positions, I first tried the inside, which didn't work well. Then I placed it on the outside (towards the peddle), and it worked fine. It shifts all the way to 52 fine. 10 and 11 or 12 is a little noisy, but otherwise ok. I adjusted the b screw based on the instructions using that white template thing. I do have to say your whole front triangle setup seems to be more vertical than mine.

 

[Velocivixen]

I’m sorry for all of your frustrations, and appreciate your diligence on such detailed mechanicals. I assure you that your documentation here will be very helpful for others. Best.

 

[Black Hawk Down]

Is it a SRAM AXS cassette? My experience with AXS on the V20 (so not Eagle) was that I had to go with AXS chain, chainrings, and cassette for it to be happy.

Cassette (Rival) and chain (GX) are SRAM. Chainring is Wolftooth. Wolftooth claims compatibility.

 

[Black Hawk Down]

I have Force AXS RD with a Shimano Ultegra cassette and have heard the same thing. Match the chain manufacturer to the cassette no matter what mullet setup you run. Black Hawk, could it be something in the app settings?

The app works fine. Not sure what you mean. It is calling out the correct components. I even tried an the latest firmware.

 

[Black Hawk Down]

That's odd. I have 2021 Q45 (current generation). I converted to AXS. I use Eagle 10/52 cassette, chain and derailleur. I didn't change the front setup though. I kept the stock 42 ring and crank. Because the chain ring has 2 possible positions, I first tried the inside, which didn't work well. Then I placed it on the outside (towards the peddle), and it worked fine. It shifts all the way to 52 fine. 10 and 11 or 12 is a little noisy, but otherwise ok. I adjusted the b screw based on the instructions using that white template thing. I do have to say your whole front triangle setup seems to be more vertical than mine.

I have a SRAM DUB bottom bracket with SRAM cranks. There's only one position for the chain ring. It does make me question if I have the right shims for the crank arms. I don't recall how I assembled them. The SRAM docs do recommend shims. I'll have to take it apart and look. Maybe my chain ring isn't centered to the cassette. I still don't understand why I can't make the spacing between the biggest gear and derailleur cog 15 mm as recommended by SRAM. I don't have any more adjustment on the b-screw to get there.

I'm 5'8" with a 30" inseam, so my peddles would be pulled more toward the back, making it more vertical than if I had an inseam of say 34".

BTW, the noise you're hearing may be due to a bent hanger. I read online that many reported fixing the noise by straightening the hanger.

 

[Black Hawk Down]

I'm beginning to believe it's my chain line. It appears to me that the chain ring is biased toward the high gear, almost aligned with it. This would be hard to center as it may require a more narrow bottom bracket to get the chain ring centered with the cassette. Hard to see in photos, but here's one anyway:



The chain line is about 2 inches (51 mm) from the center of the chain to the center of the boom. That seems like a lot, but I don't know what's correct for the Q45. I'll check with @Robert Holler. Here's the measurement:



I have an old BB for the V20. Maybe that will work.

Thanks for all the help here. It's greatly appreciated.

 

[Bo6]

There are spacers for the cassette that may help center it. I needed one on my 12 speed GX mechanical shifter to get it to shift to the 50 tooth on the 11-50 on one of my wheel sets.

 

[Robert Holler]

The chain line should ideally put the ring/rings right close to the center of the cassette. When changing cranks or rings - often a new BB is possibly needed or a ring (in the case of a single) that has an offset - most are ), 3mm, or even 6mm offset depending on the bike and what might be needed. In the case of a square taper BB - there are a lot ov variations in axle length.... it can be an exercise in experimentation to find out what works for any given set of rings/cassette/etc.... even different wheels will have different offsets att he hub and all these small mm differences can add up. :-(

The good old "standard" in the bike world. This stuff is even more compounded and an issue on uprights especially ones with very short stays.

 

[Robert Holler]

I'm beginning to believe it's my chain line. It appears to me that the chain ring is biased toward the high gear, almost aligned with it. This would be hard to center as it may require a more narrow bottom bracket to get the chain ring centered with the cassette. Hard to see in photos, but here's one anyway:

View attachment 17609

The chain line is about 2 inches (51 mm) from the center of the chain to the center of the boom. That seems like a lot, but I don't know what's correct for the Q45. I'll check with @Robert Holler. Here's the measurement:

View attachment 17610

I have an old BB for the V20. Maybe that will work.

Thanks for all the help here. It's greatly appreciated.

The correct offset isn't specific to the bike per-se but depends on what rings, etc are on there. Looking at the pic it would seem an offset ring is needed.... on the stock setup it works but it's a close call, and even then if the cassette is swapped to a bigger one the large cog has a tough time shifting, so then an offset ring is needed to get a more exact chainline.

 

[Black Hawk Down]

There are spacers for the cassette that may help center it. I needed one on my 12 speed GX mechanical shifter to get it to shift to the 50 tooth on the 11-50 on one of my wheel sets.

Yes. I believe spacers will move the chain ring further toward to the high gear. I need to move the other way.

 

[Black Hawk Down]

The chain line should ideally put the ring/rings right close to the center of the cassette. When changing cranks or rings - often a new BB is possibly needed or a ring (in the case of a single) that has an offset - most are ), 3mm, or even 6mm offset depending on the bike and what might be needed. In the case of a square taper BB - there are a lot ov variations in axle length.... it can be an exercise in experimentation to find out what works for any given set of rings/cassette/etc.... even different wheels will have different offsets att he hub and all these small mm differences can add up. :-(

The good old "standard" in the bike world. This stuff is even more compounded and an issue on uprights especially ones with very short stays.

My bottom bracket is a SRAM DUB, which is the one recommended by SRAM for the Eagle AXS GX group. I'm not sure how to specify the BB differently.

 

[Black Hawk Down]

The correct offset isn't specific to the bike per-se but depends on what rings, etc are on there. Looking at the pic it would seem an offset ring is needed.... on the stock setup it works but it's a close call, and even then if the cassette is swapped to a bigger one the large cog has a tough time shifting, so then an offset ring is needed to get a more exact chainline.

I'm not sure how an offset ring works. Does it move the chain ring closer to the BB? It looks to me like I need to move the ring closer to the BB, not further away.

Do you know what the rear dropout spacing is for the Q45?

 

[Robert Holler]

The through axle rear is 142mm An offset ring will move the chain more inwards closer to the centerline of the cranks.

How to find the correct chainring for your mountain bike with SRAM Transmission

To find the correct chainring for your SRAM-equipped mountain bike, you'll need to know your crankset model, drivetrain (Transmission or Eagle), and your bike's rear spacing. If you don't know how to find that information, we're here to walk you through it.

www.wolftoothcomponents.com

I have never found much worth to the hard and fast "this offset works" until you really get things on a frame and see with your eyes where the chainline sits.

 

[Black Hawk Down]

The through axle rear is 142mm An offset ring will move the chain more inwards closer to the centerline of the cranks.

How to find the correct chainring for your mountain bike with SRAM Transmission

To find the correct chainring for your SRAM-equipped mountain bike, you'll need to know your crankset model, drivetrain (Transmission or Eagle), and your bike's rear spacing. If you don't know how to find that information, we're here to walk you through it.

www.wolftoothcomponents.com

I have never found much worth to the hard and fast "this offset works" until you really get things on a frame and see with your eyes where the chainline sits.

Ok. Thanks. I took it apart and found a 6 mm spacer on the non-drive side and two ~1mm spacers on the drive side. I swapped them. It seems that the chain ring is now centered on the cassette, but it didn't change the behavior one bit. I was hoping that was going to do it. No such luck. All I have left is checking the hanger for straightness. I won't have the tool for a few days. If that does nothing, like I think it will, I'm screwed. It's raining here for the next week anyway.

 

[Robert Holler]

The other issue that I have (this is a general complaint/rant that I have about bike industry nerds who design this stuff) is that the reality of "good shifting" pretty much started to tank when they went beyond 10 speeds, and even then the older 9 speeds shifted much better. So what you are encountering isn't specific to Cruzbikes - it can be worse on some uprights I have worked on...The older stuff had wider chain and better error room for things being a bit off. Then they decide to cram 11 and then 12 and now even 13 speeds in nearly the same amount of space, making the chain skinnier and the gaps between cogs smaller and smaller until the tolerances are so close that "indexed shifting" has to be nearly in ideal conditions to actually work properly - even on the stand let alone when riding down a bumpy road. Also, the length of the stay can be an issue when going to larger cassettes as the angle of attack for the chain becomes more intense on the larger cogs with more strain on the rear derailleur jockey wheel. This is particularly a problem on uprights that have short rear stays.

Making all these parts tighter so it's like Rolex watch-esque gear tolerances has been a real negative IMHO for end users and bike mechanics as well. Usually the people who sit at CAD stations to design this stuff aren't bike mechanics, so... things that might look good on paper don't really pass the mechanic test in reality. But I digress...

I have worked on OLD 8 and 9 speed index shifters that are basically worn to the nubs inside the shifter mechanism and I can still get the indexing to work perfectly in a matter of minutes. Contrast that to working with some of these out of the box brand new 12 speeds where I have to fiddle with the indexing for two hours and it's still not up to a good clean shift. And I don't even want to see the new "13 speed" stuff they have coming down the pipe. And many of these wider systems - the designers had very specific frame geometries on mind when they came up with it - that may or may not be present on other/all bike designs...

All of my personal bikes have max 1x11 or 2x10 systems and I run friction top bar shifters only - no "indexing" on any of my personal bikes. Mostly because as a bike mechanic myself I wish to actually never have to work on my own personal bikes - I actually loathe working on my own bikes LOL!

 

[Black Hawk Down]

I hear ya! I personally prefer electronic shifting. I can't go back to mechanical. I'm shifting constantly to keep a constant RPM. Electronic is just a button push. Really like it. I have no issues with my Shimano Ultegra DI2 component group (1x11). I find the front derailleur shift a bit of an annoyance, even though I have syncro-shift, so I don't directly shift the front, it still causes a big jump during the shift. The rear shifting is perfect.
I thought I would try a 1x12 SRAM AXS group so no front shifting. I like the concept of the SRAM group, but I just can't get it to work. I have read lots of stories online where people are thrilled with the group I have, so it must work on some bikes. I've gone through 3 derailleurs with all the same results. I've gone back and forth with different chain lengths and b-stop positions. Finally, I aligned the chainline. Nothing I do makes a difference. It's effectively unrideable. Lots of money and time invested with nothing to show for it.

I am likely to give up on SRAM and either go back to Shimano or investigate the Rohloff speed hub. I'd like to try the latter but I'm afraid it will be another long boondoggle that may not work right in the end. I wouldn't' be able to handle the money loss.

 

[Black Hawk Down]

Just for the record, I received my hanger straightener and measured the straightness of the hanger on my Q45. It was a little off, maybe a couple of mm on one angle. I straightened it to about 1 mm. As expected. It made no difference. I'm giving up on SRAM Eagle.