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Chain not sitting correctly on sprocket
Hi all,

New member here Smile.
I just bough a new bike and yesterday was my first ride. I noticed a sound when in my 3th or 4th gear (3rd and 4th largest sprocket) .
Today I tried to determine the noise and it seems to be because the chain does not seem to fit perfectly on sprockets (if inspected, you can see small gap between chain and sprocket, causing a "click" when pedalling).

I checked the usual suspects, like high and low limit screws and also B-tension, but that seems to be OK and in other gears I can barely hear the noise.

The chain is Shimano cn m7100 SLX (12-speed), cassete is also from Shimano (Shimano Deore XT M810012 10-51 12s), Rear Derailleur Shimano Deore XT M8100 SGS.

What should I check next? It is entirely possible that I am mistaken and this is not a problem, so here is a picture of cassette and chain. If you take a closer look, there is a gap. Could this really be the problem?


Attached Files Image(s)
Hi! Is it a brand new bike or second hand? Sprockets sure look worn out to me. If you look at those three teeth at the very top, they're sooo uneven Sad
"Uphill, downhill, I like that"

It's a brand new bike - only did 40km with this bike.
Sprockets might look worn on the picture, but it is just dirt (I haven't thorougly cleaned the whole bike after my ride).

Regarding the teeth I think this is completely by design. This is a 12-speed cassette and I believe all teeth are not identical due to the fact that it is a 1 by 12 cassette. Some teeth are shaped differently to prevent to chain to fall off...but I might be mistaken.
Someone here definitely knows the answer - hopefully they will reply Smile
Ah, that's my bad! Blush I didn't think about cassette model, attached image took all the focus. It's definitely a design feature.
"Uphill, downhill, I like that"
12 speed chains and setups are very tight. That's based also on personal experience and working on my 29er, it took a while to adjust 1x12 to personal liking. My guess, the chain has not 'set in' or 'worn in' yet. It might not sound very helpful, but I'd simply suggest you to do some more riding and then observe if teeth/chain wears out a bit.

In terms of compatibility, M7100 and M8100 is a legit fit and I see nothing wrong there.
Merida Scultura 5000 (2015) & Merida Big Nine 400 (2019)

Thanks for your response. Yeah, I was also thinking that some more rides could be helpful, because like I said it's a brand new bike.
Hopefully that's the issue Smile

It certainly can be the issue. Send updates Smile
Merida Scultura 5000 (2015) & Merida Big Nine 400 (2019)
I agree with Zviedrs - chain might not be worn in yet. Give it some more miles and then lets see if it helps or not. Another potential cause can be a faulty chain, it can happen. Brand new bike with compatible derailleur-cassette-chain ...
To me a new bicycle should have some support from whom ever sold it.
There are two kinds of people in the world, "Those who help themselves to people, and those who help people!"
Where did you buy it? Online or local shop?

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