I'll add that as well as checking for broken strands every so often, if you notice your shifting starts to get sloppy for some unknown reason, closely check the cable inside the shifter for any broken strands and stop using that shifter until you put a new cable in. Cables breaking off at the head inside the shifter can be a major PITA to remove and I once had a broken strand get caught in the mechanism and broke it. No way to repair it either.