SRAM 12-Speed - Cannot set it up properly?!

[RipGroove]

Never had an issue with setting up any gears on any bike but having trouble with my SRAM 1x12 (SRAM SX Eagle Shifter & NX Eagle mech)

The H and L screws seem to be set perfectly.

There is only one barrel adjuster which is on the shifter but for the life of me I cannot find a setting on the barrel adjuster that works for the whole range of the cassette.

It sits on the bottom cog (12) and won't shift up one unless I tighten the barrel adjuster a little bit which is fine but then it'll either shift ok up until it gets to 3 but then it skips 2 and goes straight to 1, so I'll back the adjuster off just enough that it won't skip 2 but then it has trouble getting off of 12 again at the bottom.

Also it seems to have a problem around 6 or 7, it doesn't like staying put, it'll either try to go up one or down one without any shifter input, I can dial that out with the adjuster but then it has problems at the top or bottom.

The chain and cassette are both clean and oiled and I can't see any other issues so I can't figure it out??!! Anything I'm missing here?

 

[Cb750stu]

Bent derailleur hanger ?? I slightly bent my one and it sent the gears way off !!!

 

[RipGroove]

Bent derailleur hanger ?? I slightly bent my one and it sent the gears way off !!!

That's a possibility I guess, it looks straight ish by eye, I'll take the hanger off tomorrow afternoon and see how flat it is, good shout.

 

[Gyre]

That's a possibility I guess, it looks straight ish by eye, I'll take the hanger off tomorrow afternoon and see how flat it is, good shout.

Good shops will have a special tool for checking the hanger.
Easier still is swapping in a spare (good idea to have that around anyway just in case).

 

[mcboab]

The only other adjustment you’ve not mentioned is the b-screw. Have you set that to the sram setup guide? ps I also think possibly bent RD hanger & it doesn’t need to be a lot off on 12spd stuff. Also what cassette range are you setting it up on ? If trying to use a 10-52 it might be too big a range for the NX RD ?

 

[RipGroove]

To be fair I didn't think of that tbh, I guess 12 speed would be more sensitive to anything out of line. I have access to a flat granite surface table so I'll be able to see if it's bent once I get it off.

 

[RipGroove]

The only other adjustment you’ve not mentioned is the b-screw. Have you set that to the sram setup guide? ps I also think possibly bent RD hanger & it doesn’t need to be a lot off on 12spd stuff. Also what cassette range are you setting it up on ? If trying to use a 10-52 it might be too big a range for the NX RD ?

No I haven't checked the B screw (I will do though) but this is all the standard kit that came on the bike and it's all been fine up until recently, I should have mentioned that I wasn't replacing or upgrading anything currently. It just started skipping gears recently so I thought I'd take a look but couldn't actually dial it in like usual.

 

[Sander23]

I've had this on my 12 speed xt drivetrain. I went absolutely nuts spent 1,5 hour adjusting the whole damn thing until I saw a video of gmbn tech where they mention the b tension screw. It was way out of line on my brand new bike. 2 minutes adjustment and shifts like a dream

 

[Mikerb]

Eagle settings do have be pretty precise and the B tension setting is critical. Assuming he chain is not trying to go beyond top and bottom gears the B tension is really the first thing to get right. You need the newer plastic setting tool to do that with the chain on second largest cog. That also has to be done with the rear shock at its SAG point so you need a helper!
As others have said a bent hanger may also be to blame.

 

[RipGroove]

Oh jeez well I better be finding what tool I need for setting that then along with checking the hanger, cheers lads.

 

[The EMF]

Could be a simple fix like a dodgy cable and outer ? Worth checking mate

 

[Cb750stu]

Oh jeez well I better be finding what tool I need for setting that then along with checking the hanger, cheers lads.

 

[mcboab]

You can set the b-tension on 12spd sram without the tool , just follow the sram setup guide for how to without tool . I recall its a 3mm gap between the pulley wheel & 2nd largest cog (in sag position) . Guides available on the sram website .

 

[Cb750stu]

You can set the b-tension on 12spd sram without the tool , just follow the sram setup guide for how to without tool . I recall its a 3mm gap between the pulley wheel & 2nd largest cog (in sag position) . Guides available on the sram website .

Or do it properly for £6 + postage

 

[mcboab]

Theres always one. If Sram wrote how to do it . It is done properly.

 

[RustyMTB]

Everything's covered really, there's not that much to indexing gears, other than to run it all the way down to one & make sure you're happy there's sufficient tension on the cable as you metioned it wouldn't change without adding tension at the barrel. Been caught out in the past with that one.

 

[Richridesmtb]

Bent derailleur cage is another thing that can throw the shifting off.

So many people get thrown off by setting the b screw at sag. Just sit the bike on the ground and let air out of the shock until it hits the sag point. You can even stand the bike upside down and do it to make things easier to see.

Not so easy for coils.

 

[Twonks]

If it was al working ok and now isn't, with no modifications or swap outs, something has either broken or been bent.

Hanger is main culprit. Had this so many times with bikes I look after, despite owners swearing they had not dropped, crashed or otherwise had a scenario where it would likely get bent.

Not always obvious either as mentioned above.

Other than that, check for loose bolts and wear on cassette or chain.

I've also found that the inner cable routing is important on Sram mechs, with it going over the securing pinch bolt on the mech and not under it but, if the OP hasn't taken anything off it won't be this.

Or the chain has stiff links but sounds like it is well looked after so guess not.

 

[Mikerb]

Theres always one. If Sram wrote how to do it . It is done properly.

Doing the 3mm allen key measure is a good starter to make sure you do not mash the chain or jockey wheel and chain on the biggest cog and the setting will be close..within 1/2 mm, but it is not totally accurate. So follow up with the measuring tool to get it exact.

 

[RipGroove]

Cheers lads, all the info I need so I'll sort it out.

 

[James_C]

had similar last week. I detached the cable, and found the mech didn't move on its own and was kind of a bit stuck near first gear!

I took the mech off and carefully cleaned and oiled the pivots. Put it all back together and it shifts like new.

I would also suggest hold the cable at the mech end and lever ends and feel how much friction there is. It might be frayed out of sight within the outer cable.

From what I've seen no amount of screw or tension adjustments will compensate for a sticky cable/mech.

 

[Shjay]

The old Red Sram chain gap adjuster is set to largest cog & top derailleur cog, as you adjust the b screw whilst turning cranks the chain can jump to settle in place similar to barrel adjuster, whilst around middle gears where mine was jumping & now runs perfect as i fine adjusted it. The bike was upside down

 

[Mikerb]

With regard to cable tension I renewed the inner cable on my Whyte E180 RS recently because the end of the cable had become frayed. Gear change was still good so it was only done as a precaution.
It's Sram Eagle using an X01 mech and the mech needed cleaning and parts of the cable feed through it removed in order to route the cable to the stop.
I was amazed how much difference it made to all the settings to the extent that I had to reset it from scratch.

I also found that the recent hot weather and resulting fine dust that settled on the bike after every ride did not like the dry lube I was using on the chain. It is a fairly new chain and on the smallest cogs there was some chain suck on the chainwheel. A complete degrease and re lube sorted it. I think the mucoff dry lube is wax based and maybe the heat was melting it....add that fine dust and the chain was gummed up!!

 

[RipGroove]

You guys were right about something being bent. The mech hanger was a little twisted so I fitted a new one which made the shifting better but still not quite right, it looks like the mech itself is bent somewhere but I can't work out where, I took the lower cage off and straightened it but it's possibly bent somewhere around the clutch. I did try just finessing the whole thing by hand but obviously that just bent the new mech hanger lol

I might just buy a new mech and hanger for £80 and be done with it because the alternative is stripping the current mech down and trying to figure out what's bent when it could end up just being a combination of small errors like, lower cage, something else slightly bent, bit of lateral play here and there all adding up to an amount that causes an issue so I could end up chasing my tail a bit.

 

[RipGroove]

So yeah I've just ordered a new mech, hanger and gear cable so that should sort it out.

 

[steve_sordy]

You can get a mech hanger gauge and alignment tool for less than what you paid for a new mech and hanger. (I bought a Parktool one for £50, but that was a couple of years ago. There are cheaper versions that look the same. If you have 12-speed and go in harm's way on a frequent basis. then the alignment tool will save you time and money. They are quick and easy to use, which is why my LBS used to only charge me £10 for hanger alignment. But it was the loss of bike, the travel time etc that was a proper bind and decided me to buy one for myself.

PS: You don't have to hit the mech on a rock or a stump, to bend the hanger. Catching the mech arm on a pine sapling will do it, leaving no scratches or other impact signs, just a bent hanger or mech arm, or both.

 

[RipGroove]

You can get a mech hanger gauge and alignment tool for less than what you paid for a new mech and hanger. (I bought a Parktool one for £50, but that was a couple of years ago. There are cheaper versions that look the same. If you have 12-speed and go in harm's way on a frequent basis. then the alignment tool will save you time and money. They are quick and easy to use, which is why my LBS used to only charge me £10 for hanger alignment. But it was the loss of bike, the travel time etc that was a proper bind and decided me to buy one for myself.

PS: You don't have to hit the mech on a rock or a stump, to bend the hanger. Catching the mech arm on a pine sapling will do it, leaving no scratches or other impact signs, just a bent hanger or mech arm, or both.

I didn't know such a thing existed, I'll try and get one then to maybe sort out my old mech and hanger so they don't just go in the bin.

 

[RipGroove]

Just googled the hanger alignment tool, I can make one of those if I figure out how it's supposed to work. Also that won't help with a bent derailleur though will it? Because I suspect mines a little bent somewhere, and not the lower cage.

 

[TheRealPoMo]

I'd just buy the Parktool. Unless you have a workshop with tools you can drill and tap thread to 90.0 degrees accuracy, it's useless.
My previous bike had SRAM and was flawless until one day, and no matter how many times I adjusted according to instructions, it was dodgy. Parktool was not available so I just bent it using eye method and hey presto, all good. I must have bent it at some point but no memorable crashes....When Parktool became available, I grabbed one (can never have too many tools) and it was perfect when I tried it out. Probably more good luck than expertise, but I have the tool now.

 

[RipGroove]

I'd just buy the Parktool. Unless you have a workshop with tools you can drill and tap thread to 90.0 degrees accuracy, it's useless.
My previous bike had SRAM and was flawless until one day, and no matter how many times I adjusted according to instructions, it was dodgy. Parktool was not available so I just bent it using eye method and hey presto, all good. I must have bent it at some point but no memorable crashes....When Parktool became available, I grabbed one (can never have too many tools) and it was perfect when I tried it out. Probably more good luck than expertise, but I have the tool now.

I'm a machinist by trade so odd threads and accuracy isn't a problem