The time to replace sprockets isn't after the teeth are severely curled or worn down to a nub. Or when the chain starts jumping the cogs. To maintain top, reliable performance of your bike and to minimize damage to other components, sprocket replacement should happen long before then. But how can we know when those gearwheels have served their useful lifetime? Here are a few simple ways to know if your final drive is due for a swap out to new components.
Just as it's best to see a doctor now and then for a check-up instead of waiting until you've got a serious problem, it's a good idea to do regular check-ups on your machine before things get bad (and expensive!). Taking just a few minutes each week to check out these handful of things will help you determine if you've got an unhealthy final drive.
Examine how well the chain meshes with the sprocket teeth. With a healthy chain and sprocket, the individual chain rollers align perfectly with the spaces between the sprocket teeth and fit down into those U-shaped grooves evenly.
Take hold of the chain at the back-end of the sprocket and try to pull it away from the teeth. If there's a significant gap (assuming the chain is adjusted properly), the chain is worn and the sprocket is likely worn as well.
Look closely at the sprocket teeth to see if they have become sharp at the tips and/or slightly curled. The teeth on a new sprocket are straight and have a flat or domed shape at the tip. If the teeth are sharp, the sprocket is worn.
Look for indented wear around the circumference of the sprocket at and below the teeth that resembles the shape of the chain. This “shadow” wear indicates a well-worn sprocket that should be replaced.
If you do see sufficient sprocket wear, don't cut corners; replace both the front and rear gearwheels at the same time. Oh, and be sure to replace the chain as well to avoid rapid wear of your new components.
Swapping out the old for new? That's a great time to consider upgrading to premium components or changing the gearing of your bike for better performance, improved fuel economy or to eliminate an annoying vibration.
How long do sprockets and chains last? The answer is, “it depends.” Some riders get years of service from a chain drive system while others get only a few months of life from their components, depending on riding environment, riding habits, and regularity of maintenance. Here are a few things you can do to assure lasting performance from your sprockets:
Repeated jerky throttle use and rough shifting wreaks havoc on a chain drive system. Learn from the racers: smooth throttle transitions and seamless shifting preserve equipment and are the mark of skilled riders.