New chain, noise from jockey wheel

I fitted a new KMC chain to my MTB commuter as to old one had got to 0.75%, I now get a loud clicking/whirring sound that seems to be coming from the lower jockey wheel (as far as I can tell when it's on the workstand). The noise is there in all gears, and is constant when the chain is rotating, what I mean is that it's there all the time the chain is moving, not just once per revolution or whatever. The idexing is good and changes are smooth. I haven't lubed the chain as it came fairly well lubed, but I will try this.

This is the first time I have changed the chain since I replaced virtually the whole drivetrain last year (including cassette and rear mech), so the bits are only 1 chain old. Is it possible that the jockey wheel has worn out, even though the cassette is fine?

I gave everything a good clean including squirting with muck-off and rinsing, is it possible I have borked the jockey wheel internally somehow?

I thought it might settle down after a few miles, but it's no better after one 20-mile round trip commute. I've changed quite a few chains before, never had this problem though! Any help gratefully received.
 

Tim Hall

Guest
Location
Crawley
Have you threaded the chain through the derailleur correctly? A common error is to have it pass outside of the tab that separates the two halves (and acts as a sort of guide) giving the noise you describe.

Not that I would ever do such a daft thing. Oh no, not me sir, no way. Honest.
 
Location
Loch side.
Tim may well be right, it is a common rookie mistake although the mechanics in my workshop all managed to do it at least once a year, not coinciding with the first day of April either, but curiously proportional to the customer's lack of humour.

The second thing to look for is worn jockey wheels. The outside edge of the wheel needs to look like a series of flat-topped butes, not sharp peaks.
 

gbb

Legendary Member
Location
Peterborough
That whirring sound is not ununsual, ive had it happen at least twice when fitting a new chain to part worn components, I suspect its just everything bedding in together. It'll disappear after a few rides.
Its not necessarily anything to do with incorrect chain or fitting, it'll go, relax.
 
Have you threaded the chain through the derailleur correctly? A common error is to have it pass outside of the tab that separates the two halves (and acts as a sort of guide) giving the noise you describe.

Not that I would ever do such a daft thing. Oh no, not me sir, no way. Honest.
Do you mean like this?
wrong.jpg


I'd like to make it clear that this is not an actual picture of my actual bike taken last night at all, I merely use it as an example of how things could go wrong if someone were to commit such a schoolboy error.

It's amazing how much quieter the bike seemed this morning....:whistle:
 
Location
Loch side.
Do you mean like this?
View attachment 80153

I'd like to make it clear that this is not an actual picture of my actual bike taken last night at all, I merely use it as an example of how things could go wrong if someone were to commit such a schoolboy error.

It's amazing how much quieter the bike seemed this morning....:whistle:
It is incredible how stupid some people are. Does the alleged hypothetical culprit now have a new arrow of experience in his or her quiver of bike maintenance tricks?
 
Location
Loch side.
And tell the alleged culprit that his/her jockey wheels are still perfect and there's no need for replacement as some other idiot suggested.
 

gbb

Legendary Member
Location
Peterborough
That whirring sound is not ununsual, ive had it happen at least twice when fitting a new chain to part worn components, I suspect its just everything bedding in together. It'll disappear after a few rides.
Its not necessarily anything to do with incorrect chain or fitting, it'll go, relax.
^^^ the above posts just go to show...don't believe anything i say ^_^

TBF, i have had that whirring sound a couple times and it isnt neccessarily down to any mis routed chain, it can stop after a while.....equally as i have learned...you CAN easily route the chain incorrectly and have a very similar sound. One i'll watch for in the future.
 
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