Even if you lubricate your motorcycle chain after every ride, clean and lubricate it regularly, and adjust it within the manufacturer’s recommended specifications, you’re only going to get so many miles on your bike before you need to change both the chain and the sprockets. Yes, you might be able to get away with changing the sprockets every other time you change the chain, but you’ll find the second chain has a shorter life due to the wear on the sprockets.
Over the miles as the pins of the chain roll across the sprockets, they both wear, and the chain becomes lose/stretched. Your owners’ handbook or the dealership will give you the specifications on the amount of play, but as a rule of thumb, the bottom loop of the chain should move no more than an inch when depressed halfway between the gearbox and the back sprocket.
If there is more than an inch of play or the amount of play recommended for your bike, you can adjust the chain’s tension (we’ll save the “how to” for a different article) a number of times before replacement. When it comes time to make adjustments, you want to get the amount of play within the recommended specs because when a chain is too loose or too tight it causes unnecessary wear.
Some ways you can tell when it is time to replace a motorcycle chain and the sprockets: if the back sprocket’s teeth are worn down and look like hooks, there are links that stick or kink, it feels rough when changing gears indicating varying wear patterns on the links, or when the frequency of adjustments increases.
With a lot of maintenance on a motorcycle you can get away with waiting just a little too long, but with the chain and sprocket, it is always better to replace them early rather than sitting on the side of the road.