Noise with new sprocket

andUK

I have just bought a second-hand Specialized Langster 2014 that came with a 48T/16T. On the track this was pretty noiseless; I noticed this as several other bikes on the track seemed quite noisy.
The above gear ratio was too low, so I have just replaced the 16T with a 15T Miche 1/8 sprocket.
I have yet to take it to the track but just spinning the pedals a lot of noise is coming from the chain where it contacts the Miche sprocket.
I have measured and verified that I have an 1/8 chain and chainring.
I have spun it with the chain a bit loose and at the correct tension (approx 12mm play at the tight spot) and with the chain tight. None of these set ups has made any difference to the noise.
Is this normal when a sprocket is first new? Do they quieten after a bit of usage?
I'd be grateful for any useful advice.

nicklouse

Check you alignment. Look at the front cog from the rear cog along a length of the chain. See the bends?

andUK

I've checked the chainline visually - absolutely straight,
and by measuring - chainring centre at 42mm from frame centre and
- sprocket centre at 42mm from centre of dropouts

nicklouse

How worn is the chain?

andUK

Chain and chainring in very good condition.

andUK

Put a straight edge between chainring and sprocket and there is just a fraction of a mm difference, which, from what I have read, should be all but insignificant.
Also, having read articles elsewhere concerning drivetrain noise maybe certain setups are noisier than others and maybe in particular when putting used and new stuff together. So maybe the solution is that there is no solution, the setup is fine, just a bit noisier than the previous one and all will be fine on the track.

imposter2.0

Chain tension will affect noise, but if the noise has only just started after swapping the sprocket (and assuming the chainline is not massively altered) then it sounds like the chain is more worn than you think.

I had the same issue recently with a new chain and an old sprocket - the sprocket looked ok, but the transmission noise disappeared when I swapped it for a new one.

nicklouse

andUK wrote:

Chain and chainring in very good condition.

So I guess you don't have a chain checker.

It is a good thing to have.

If the chain is worn the chain will only pull on one cog and then when that one disconnects the chain jump forward to catch up the next.

It will wear in and quieten down as the cog wears to suit.

47p2

Some sprockets are noisier than others, I have Dura Ace sprockets which are really loud when new but they do become quieter when they are broken in. Never tried Miche sprockets so cannot comment on them

imposter2.0

I have Dura Ace, Miche and Halo sprockets - the DA is the oldest/most worn, but only became noisy when it was paired with a new chain.

andUK

Thanks for the above posts, they have been very helpful to me as nocive reagarding track bike set-up.
I have checked the chain and measuring it over 12" it is indeed spot on. (By comparison I measured my MTB chain which I know to be worn and indeed it measures 12 and a 1/16").
Given that alignment is good, the chainring and chain are quite unworn, I think it reasonable to conclude that the Miche just so happens to create a bit more noise than my original sprocket and in this case it's probably not indicative of a problem.

paddlemyowncanoe

Lube may help.

andUK

Have succeeded in totally eliminating the noise from the new sprocket by selling the bike.

imposter2.0

That's a bit drastic...

slam that stem

I reckon the chain tension was too high. That's what causes it for me anyway