I always sort of assumed that cables just break. They do, but you can prolong their life with some lube.
I kept snapping clutch cables, on my old BMW motorcycle. A knowledgeable friend asked me what I was lubricating them with? When my reply was "Aw, come on! How do you lubricate a cable? It is in a nylon sheath!" He just sent me a photo of a cable luber. This simple device is cheap and ingenious.
Seal one end of the cable sheathing inside the rubber gasket of the luber. Insert a straw from a can of aerosol lube into a port on the device and pump away. Lubricant will spritz out of the lure, but if you have everything in place, it'll also shortly spray or leak out the far end of your cable.
You can do this on the bike with cables already in action, but remember to set some rags at each end to catch the "overspray." I felt a noticeable difference in how a new clutch cable slid through the sleuth after pumping a bunch of BelRay 6 in 1 into it.
I'm going to forgive myself for not knowing about lubricating cables. This will almost certainly increase their lifespan.
