Light chain noise

[EasyPeez]

Warning: what follows is terminally dull...

So I've seen people mention on various threads on here about how they like to have their bike running perfectly, so that only the sound of tyre on tarmac can be heard on a ride. I'm of the same mind myself.

However, while this is perfectly possible on my Boardman CX, I can't achieve it on the Genesis. On the latter there is always some chain noise when in the larger front cog.

It's not especially annoying (it's a light 'singing' of metal meeting metal rather than a grinding or rattling that suggests something is misaligned).

I'm not really looking to fix anything, as I don't think anything's wrong. I just don't get why this would be.

Both bikes have FSA cranks and chainrings (although different models) and both run identical KMC chains, dipped in the same White Lightning lube. The Genesis is the better maintained bike of the two (i.e kept immaculate). I degrease and relube the chain every 200 miles or so but this makes no difference, nor does it change when I fit a new chain and/or cassette. The noise has always been a feature since I bought the bike 2 years ago, and it was only when I acquired the second bike some time later that I realised some light chain noise wasn't just an essential aspect of riding a bike!

It seems odd that the chain makes no sound on the small front ring, but it does on the larger ring. If anything I would have thought this would be the other way around, as the chain engages and disengages less often when on the large ring. The noise also seems to decrease the smaller the cog (higher gear) I'm in on the rear cassette.

I keep the indexing adjusted perfectly and there are no problems with anything to do with the drivechain that I am aware of, nor do my chains wear any quicker than I would expect them to.

Any thoughts?

Cheers.

(And if you've read this far, you can't say I didn't warn you!)

 

[Heigue'r]

Is it rubbing on the front derailer?..slight barrell adjustment on the cable should fix it?

 

[Yellow Saddle]

You don't mention chain health at all. Have you measured your chain?
An elongated (worn) chain has a pitch larger than that of the front sprocket (rear sprocket works differently) and since it enters the sprocket under tension, is fully elongated when entering. Since the holes in the chain are now further apart than the teeth on the sprocket, the incoming chain crashes against the incoming teeth, causing a vibration that's only noticeable to the mechanically sensitive.
Until you've measured your chain, everything else is just a guess.

 

[Globalti]

It's possible your ear just happens to be attuned to the noise and you are a bit paranoid. When I used to motorbike I was constantly hearing new noises from the engine, which I would attribute to piston slap or bearing knock. I used to strip the engine and find nothing wrong and the engines never blew up.

 

[I like Skol]

Frustratingly my 'best' bike does this too. I have checked and checked again, made a myriad of tweaks to indexing, trim, alignment, B-tension screw, stop screws etc but particularly when on the large chainring it sounds like the chain is running onto the chainring or rear sprockets not quite right? I can't see any reason for it, chain line looks reasonable but it almost sounds like the bottom jockey wheel meshes noisily when the chain is a bit tighter on the big chainring? It is Shimano 105 and has no wear on this jockey wheel. If I could stop this noise I would be a happy man because I have other bikes that do achieve the near Zen like tranquillity I desire....

 

[Yellow Saddle]

Frustratingly my 'best' bike does this too. I have checked and checked again, made a myriad of tweaks to indexing, trim, alignment, B-tension screw, stop screws etc but particularly when on the large chainring it sounds like the chain is running onto the chainring or rear sprockets not quite right? I can't see any reason for it, chain line looks reasonable but it almost sounds like the bottom jockey wheel meshes noisily when the chain is a bit tighter on the big chainring? It is Shimano 105 and has no wear on this jockey wheel. If I could stop this noise I would be a happy man because I have other bikes that do achieve the near Zen like tranquillity I desire....

What you are describing is very common on short chainstay bikes. It has to do with the angle between jockey centre plane and chain.

When you are in big-big (or close to such), then the jockey cage is bent forward, making the distance between tension pulley and the bottom of the chainring shorter than when you are in a smaller gear. Therefore, the angle changes of the chain run changes with gear size because the jockey pulley moves left and right and, goes shorter and longer. When it is at its shortest, the angle is the biggest. The problem is that the jockey cage and therefore the pulley doesn't change angle, it remains parallel to the bike's centre line. When big big, the angle is maximum and the jockey wheel constantly wants to derail. Only the pulley tooth profile prevents it from derailing. However, in that position it is noisy since the teeth don't fall square into the chain holes but hit the sideplates and then slide into the holes.

You can improve it a bit by running the chain slightly longer than recommended and avoiding the extreme small/small combination of gears.

 

[EasyPeez]

Is it rubbing on the front derailer?

Nope. I recognise the sound of derailleur rub and this is different. My front derailleur is set perfectly.

You don't mention chain health at all. Have you measured your chain?

I degrease and relube the chain every 200 miles or so but this makes no difference, nor does it change when I fit a new chain and/or cassette.

Current cassette and chain are less than 500miles old and the noise was identical on my old, worn chain and cassette as it was on my brand new chain, as it is on my 500 mile old chain and cassette.

It's possible your ear just happens to be attuned to the noise and you are a bit paranoid

Possibly. Though not paranoid, just curious to understand. I don't think there's anything wrong as such. But one bike definitely does run silent and the other not.

It sounds like what I am describing is pretty much what @I like Skol has going on. And so @Yellow Saddle 's explanation about the jockey cage angle would seem to make perfect sense. I might try leaving a couple of extra links in the chain next time I change it, and see if that helps.

Thanks.