New SLX drivetrain noisy and rough feeling

Fitted new chain, 11-46 cassette, mech and shifter to my daughter’s bike. It works but it feels quite rough, which I was not expecting. I can feel the links moving across the components as I turn the pedals in the workstand.

Usually, this is caused by the installer getting the chain the other side of the little flat thing in the mech cage, but I checked this having made the mistake many times in the past. The KMC chain I bought seems a little thicker than the 11sp SRAM I have on the other bike, but I swapped the KMC for another SRAM and it was the same.

The only thing I can think of is the cheap stamped steel chainring is just crap. Anyone had this issue with crap chainrings before?

Had a similar issue with my XT recently, seems I managed to get some muck between the parts of the cassette when fitting, it made the chain release from the cassette noisily. It was an absolute sod to diagnose.

From experience, check the chain is routed through the rear mech correctly.

Have had this with a worn chainring

Is it a new chainring and nw?

B screw needs adjusting, or bent hanger?

Chain direction can be an issue.
Shifting ramps on the non-printed side and go on the inside.

(I think KMC are non-directional but some Shimano ones are – just something else to think about)

Other than that – maybe the chainring is not the right width.

Hard enough to diagnose these things with the bike in front of you, let alone over the internet. Good luck!

KMC chain is non-directional, it says.

I think it’s cos the chainring is not an 11sp specific one.

Fitting anything else will require some elegant bodging.

KMC 11 SPD chains are noisy. We stopped using them because of the noise.

Not staying that’s your specific issue but if you move from SRAM to KMC you should expect more noise.

That’s the one I have.

As well as that if it’s a new nw chainring you may find it beds in and quietens down. I had a Shimano chain which was noisy over a new superstar oval nw ring. After 3 or 4 rides it got a bit quieter.

So, I added in another chain link cos I’d shortened the chain. This left top gear looking very slack but there was lots left on the b tension screw so I wound it in loads. There’s now a big gap between sprocket and jockey wheel but it works much better.

weird ..you’d think increasing the gap with the b tension would make things worse if anything ..why did you add in another link out of interest did you think the mech / chain tension on the 46 cassette cog was too tight?

weird ..you’d think increasing the gap with the b tension would make things worse if anything

Well increasing the gap increased the tension slightly but the extra link reduced it by much more, the cage is at a less acute angle now.

The chain came with I think 116 links, I took one out because then the mech angle ‘looked right’ based on my experiences with 9sp. But the tension might’ve been too great.

I threw out the instructions with the packaging, so I don’t know what Shimano recommend.

I had an issue recently with a very noisy KMC chain on a Deore 11-42t cassette, both brand new and 10 speed.

I couldn’t find anything wrong with anything, so just rode it for a couple of rides and it seemed to calm down.

Never had such an issue with Sram chains.

I’ve recently set up the 11spd with a kmc chain. It’s a bit noisy for me too. The instructions that come with the Shimano kit are very basic now. The dealer manuals on their website have all the tech instructions. For chain length they recommend the two links overlap with biggest chairing and sprocket. I saw a video ages ago where it recommended 4 links for a one by setup. Started with that, but the shifting was sloppy. Took two links off and the shifting is better, but still noisy. May have to play with b tension, and possibly adding a link.

Rear mech routing and b screw would be my first things to check.