Anyway, if cables have been rubbed through and you can see the outer sheath wires, would you swap them? Nothing broken and nothing sticking out but I wonder if they could rust through and then impede shifting a bit? I know there's an inner tube as well but I'm tempted to just get them swapped out before something goes south.
Replace. The plastic sheath holds the longitudinal gear cable casing strands in alignment. Without the plastic sheath’s restraint all the way round, you get excessive deflection and bad gear changes.
I'm an idiot. It's DD turbo. Different cassette.
Anyway, if cables have been rubbed through and you can see the outer sheath wires, would you swap them? Nothing broken and nothing sticking out but I wonder if they could rust through and then impede shifting a bit? I know there's an inner tube as well but I'm tempted to just get them swapped out before something goes south.