V8 – yeah thanks for that – literally just checked that after reading your post. However…lockring very tight.

Tried adjusting tension, tried checking b screw. Tried everything….think my next step will
Be a new chain.

Fingers crossed

My thinking is it’s uneven wear on the cassette , let me explain.

Having got pissed off with killing complete chain sets , every couple of months , I attempted the ‘3 chain drive train ‘

As in ,you fit a new chain set , then buy 2 additional chains. Theory is if you change the chains in rotation every 2 weeks ( or what ever ) the whole chain set will last much longer.

Well 2 weeks in , I changed the chain & guess what ? There was an annoying vibration , almost grinding noise & under load would skip on my 2 most used sprockets!

Conclusion , the tolerances are so fine on 10 speed kit , the slightest uneven wear can ruin your day.

Ha yeah good point Doh! Killed an hour at work over engineering a tool on my colchester lathe and mill has a knurled Handle too ! Absolutely serves no purpose whatsoever.

Lol 😀

I had this today, I didn’t have it on my last ride but have it now. It is also only under load, the more load the worse it is. The whole drivetrain was secondhand in Feb so I’m no surprised. 2×9 so obviously different to the op. Happens in both rings and is more obvious is the lower end of the cassette. It almost felt like the mech wanted to change gear but seemed setup fine. I hosed it down and lubes the hell out of the chain and am hoping for the best. It looks like I will be going 2×10 sooner than originally planned.

Did anyone get to the bottom this? I have a full xt 10 speed setup, kmc chain. Noise seems to be from when the chain leaves the top jockey wheel. Everything straight. Not sure if I should invest in a xt chain to see if that helps.

And here I am, in exactly the same situation as the OP. Except my chain is brand new (1071 SRAM), my cassette is brand spankers (XT 11-36), the XO mech and shifter are as new and set up perfectly. It started on a big climb on first ride out with this set up as a 2×10.

So far;
I have swapped out BB for brand new – no change
I have swapped to a single front chain ring – no change
I thought I had it when I checked the jockey wheels as there was a tooth missing so changed it for a good one off other bike – no change
I have changed back to my old 9 speed cassette -no change

It is only under proper load i.e. climbing, that is the thing. Cannot reproduce it in the stand.

I will try my 9 speed chain next and if that doesn’t change anything I am stumped….. unless…… it could be the rear wheel bearings. I have XT wheels and I recently (3 rides ago) regreased them and took out a little bit of play. Could this be the source of all my pain?

If you have ruled out all the gears then it must be something else

What’s the freehub and wheel bearings like?

Is the rear quick release clean, degreased and re oiled?

Do you have the right number of spacers on the bottom bracket to get your chainline right?

Have you put the cassette on properly and not missed a spacer?

And dare i say it…….Do you have a crack in your frame?

Good luck. Noises are so annoying when you can’t find them.

Freehub and bearings currently number one suspect

Quick release OK (it is a 142×12 Maxle)
Chainline should not be the problem as it did it in both rings with 2×10 set up and still does it on single ring and in all 10 speeds.
Cassette can’t be the problem as it does it with 10 speed and 9 speed cassette
Crack in frame. Hope not! After the long climb when it first came to light I did an equally long and very rocky descent and bike is still in one piece! Will give it the once over though.
Going to change the chain for my old 9 speed one briefly and see if that changes anything

How can a frame crack create a transmission grumble? Or hub bearings?

I had a noisy do drivetrain, seemed to be caused by the newish chain not meshing with the worn chainrings. It seems the chain would walk up the side of the teeth at the top of the chainring, causing a crunching noise. Once it got halfway round the chainring the chain would slacken off and slip back down onto the chainring and this gave a gritchy feel when pedaling.

I thought it was something like that initially (Though this is a brand new chain & cassette). I can however recreate that sound by adjusting the tension to the rear mech until the point the chain try s to ride up the next gear. Backing it off causes the sound to go away. I have tried 3 different front rings and the sound is identical with them all.

How can a frame crack create a transmission grumble? Or hub bearings?

If you have ruled out all the normal suspects then it must be something else.

A crack in the frame may cause the rear swing arm to be out of line causing a grumble

A collapsed bearing may cause a grumble when you rotate the wheel making you think its the gears

I just had my cassette and chain replaced and ended up with a terrible racket down below.Turned out the new chain was slightly sticking to the chainring and would only do it under load.See if you can have someone look there when you are riding or try having a look in that spot yourself.Took me ages to find where the noise was coming from but eventualy could clearly see how the chain was ever so slightly sticking to the teeth.

I am back 🙂 in my case the problem was worn chain rings. After all my flumoxing about focusing on everything else (and trying other chain rings that had been used) I just bought some cheap Deore rings from crc for 8 squid ish and boom…. No more grinding noise for me.

Well it seems caffeineoldbean and Doncorleoni are both spot on. I ran the bike upside down and held the back wheel while pedalling by hand. At the point just before I could not turn the pedals anymore the chain stuck to the last 3 links on the front chainring and was dragged round a little to be released with “the noise”. Thing is you can see it happening but the noise still (appears to) comes from the rear cassette area.

So thanks for all the nelp. I think the conclusion of this thread for anyone finding it via Google like I did is to check the chain, under load, coming off the bottom of the front chainring before anything else.

RESULT 😀 😀 😀

And the final word! I have now fitted a new 10 speed narrow-wide front chainring …. et voila.. problem solved. Quiet as a mouse