[Closed] Drivetrain noise in 50T cog

is the derailleur correctly aligned? If it's not quite far enough over (towards the spokes) mnaybe the chain is being pulled off the teeth as it crosses over to the cassette? Try relasing the low screw by a very tine amount - like a quarter turn max

Thanks for the suggestion.

I’ve just tried tweaking the low screw in quarter turn increments while spinning the chain but unfortunately it doesn’t seem to be having an effect.

Have you recently changed the chain? I get the same annoying noise also only in the 50T cog every time after putting on a new chain. After endless sessions adjusting everything with no luck I found that it tends to last a couple of rides then disappears on its own.
I assume that the differing wear on the cassette & chainring combined with a new chain just doesn't play well together until it all settles in so I just put up with it & try to do a couple of rides with spinning in 50T climbs in quieter places. But I'm most likely completely wrong!

Is your chain long enough? Add a couple of links and see if that helps...

I haven’t recently changed the chain but I have moved the entire drivetrain to a new frame with 5mm longer chain stays. I wonder if that extra 5mm is enough that it needs another link or two? The chain is at about 0.5% wear so I suppose a new chain which I could set with a few more links might be in order.

I had the same noise recently over the lowest four or five gears (bigger cogs on cassette) after replacing mech, chain and cassette, but with older chainring. It Disappeared after a couple of rides.

Chain length for 1x here.....5mm makes a total 10mm difference in chain length which is about one link. Probably worth checking, derailleur looks a little strained.
https://www.parktool.com/blog/repair-help/chain-length-sizing

Given that a few people reckon chain length and the that the chain is getting on in terms of wear I’ve ordered a new one.

Thanks for the suggestions, I’ll report back!

How tight does the chain feel when on that cog? If the chain's too short it's normally quite hard to shift into that gear - as in resistance from the shifter.

Have you recently changed the chain? I get the same annoying noise also only in the 50T cog every time after putting on a new chain. After endless sessions adjusting everything with no luck I found that it tends to last a couple of rides then disappears on its own.

I had this and put it down to the chain edges being less worn and causing the noise. Went away eventually.

Incredibly my new chain is here 18 hours after ordering it. It’s in a bean can full of degreaser and I’ll report back once it’s fitted.

It sounds like if my problem is chain length that I might get the same sound after swapping for a new one anyway so I suppose I’ll have to give it a few outings before deciding whether it helped.

my new chain is here 18 hours after ordering it. It’s in a bean can full of degreaser

Nah man. The factory lube is worth keeping on for a while.
Too late I guess.

Last time I ran a chain with the factory lube it came home caked in sand and I ended up having to scrub it out anyway. Maybe it depends on the dirt but round here anything sticky on the chain is no good.

Its only inside the rollers that need lube, so always wipe the chain down when you've finished lubing it, the chain should not be sticky.
Spray a cloth with WD40 or similar and wipe, never spray onto the chain.

Nah man. The factory lube is worth keeping on for a while.

Nope!

Factory lube isn't chain lube, it's a thin oil coating to stop rust. It performs badly in friction loss and chain wear tests, of which you can find loads on:

https://zerofrictioncycling.com.au/

ZFC recommends doing the first ride with it on using it to collect swarf from the new chain, then fully degrease and apply a proper chain lube.

It sounds like if my problem is chain length that I might get the same sound after swapping for a new one anyway so I suppose I’ll have to give it a few outings before deciding whether it helped.

Lube or chain lube regardless, Worth doing the chain length check and keeping the spare links so you have a chance to see how length impacts the smoothness of your drivetrain

New chain is on, initially with a link more than I thought I’d need (just to check because why not). The noise went away but also the chain was too long so I took another link out and now it’s quieter but not silent.

I can hear the noise in the workstand but not on the trail so I guess (hope) what I’m hearing now is the noise others describe from a new chain and that it’ll go away as things bed in.

All my 1x setups have made a similar noise in the lowest gear pretty much forever.

If that's all you have to worry about with it, I'd just ride and forget it. Chances are it won't be audible on a ride anyway.

edit. I listened again as when re-reading the OP a tick was mentioned. Didn't hear that first time round and I was referring to the rumble noise.

Ticking is a bit weird. If it is still happening, can you pin point when it does it by turnign the cranks slower? Might be a shot bearing or damaged tooth in the jockey wheels for example.