Originally Posted by
randyjawa
What causes chain noise? Some bikes I have owned were as silent as can be, while others not so much. I recently installed a NOS Legnano cottered crank on my, (duh) Legnano Grand Premio and the chain is noisy, to say the least. The noise does come from the crank ring to chain contact and nothing is rubbing anywhere that I can see. Just the noise of the ring teeth engaging the chain..
ex
It takes much longer for steel chains and steel rings to accommodate imperfections in fit through wearing down, and may never wear together as smoothly as steel/alu, and so be more prone to making noise. Steel on steel sounds louder too, for a given force, ( I'm thinking of bells, but it should be valid, no?)
After ruling out obvious noise from rubbing derailleur guides, I look for unequal component wear due to replacements or drivechain changes. Properly lubed chain, freewheel and chainrings mesh more smoothly over time, and generally become almost silent, (before wearing out). If pedaling is not quiet at that point, freewheel/wheel/chainring/rear derailleur alignment would be my next check... My last(maybe should be first, depending on the build) check would be component/brand compatability.