Chainstay length and chain performance

earth

Does chainstay length have any effect on the smooth runnning of a chain?

I ask because I notice the chain on my Giant TCR runs much smoother than on the Orbea. Both are from the same era except the Giant has a Shimano chain while the Orbea has a KMC. If I flip both upside down and turn the cranks slowly the Orbea chain does not seem to sit on the jockey wheels comfortably. At minium effort it resists turning, the deraillure bumps about and it's always noisey. The Giant runs noticeabley more smoothly with less effort, shifts better and is silent. It could be the chains are slightly different but does chainstay length matter? Some muliple of the length of a chain link would seem appropriate.

mercia_man

A bike with short chainstays will be rougher and more noisy at the upper and lower ends of the cassette when cross-chaining because the angle of the chain is more extreme.

But your problem sounds more like you need a new chain and possible a new cassette for your Orbea. Or maybe one or more links are a bit stiff and the chain needs cleaning and lubricating. Or maybe your rear mech indexing needs adjusting.

earth

It could be any of those things or it might be jockey wheels. I looked a the geometry of the two bikes and the chainstays are exactly the same length. I recently straighten the hanger recabled and reindex. I check the chain for stretch reguarly and keep it lubricated. But it has always been a bit noisey. It just looks like the chain rides on top of the jockey wheel and cassette teeth for a moment before it drops down into the U between teeth. Like it does not quite fit. The Giant is noticeably smoother.

The Rookie

Sounds like the chain is stretched and busy wearing out everything it touches.

trailflow

It's possible the chainline between the two bikes is different. The chainset/bb's are spaced differently or the chainrings have a different offset or both.

Are they all the same brand/model/size ?

pilot_pete

Could be numerous things. Most likely is worn components by the sounds of it.

How 'new' is each set up?

Apart from the differeing 'geometry' already mentioned other considerations are

Chain length. One could feel 'sloppier' than the other, especially if one chain is a fraction too long. Look at the manufacturer's website (Shimnao is great) for chain length guide, or look on Park Tools website. They have different methods for determining chain length.

Chain wear. Have you got a wear guide? Only cost a couple of quid so not worth faffing with a steel rule to measure chain wear. If excessively worn it could be damaging the teeth on other components.

Cassette wear is next most likely if chain is worn (or if you have already changed chain a few times with the same cassette). Look closely at the teeth from side on. Instead of being U shaped they will start to take a more slanted U where the chain rollers have bitten in. Also, with a correctly adjusted rear derailleur the shifting becomes less smooth or the chain jumps on a worn cassette, even if it is a new chain if the cassette is really worn.

Have you ever changed the jockey wheels if the set up is several thousands of miles old? These can wear (but not to the same extent as the other components as they don't take the pedalling force from the chain). Have they ever been removed, cleaned and lubed? Do they run freely, is there excessive play in them? Cheap and simple to change.

From your description I think some, or many of your components are worn.

Cheers

PP