Like that first cup of coffee and a post-ride high: nothing lasts forever—not even your chainring. A well-maintained chainring will last longer than its chain and cassette counterparts, often several times over, but inevitably, the time may come for you to replace it.
The good news is: It’s easy to replace and the signs that your chainring is past its prime are easy to spot. The teeth will be visibly worn-down to a defined point—by comparison, the teeth on a new chainring are flat at the top— and the chain may stick to it instead of easily releasing while pedaling.
If you’re replacing your chainring(s), it’s a good time to check your cassette and chain for wear, too, and possibly replace those at the same time since they wear down together. (Here’s how to replace your cassette and how to replace your chain.)
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Below, we cover how to replace a single or double chainring, how to remove your crank to access it, and which tools you’ll need for the job.
What You’ll Need:
- Hex wrench set or Torx wrench set, depending on chainring bolt style
- Nut wrench tool, depending on chainring bolt style
- Threadlocker, like Loctite
- Bike grease
- New chainring
- Torque tool, preferably, to properly tighten chainring bolts and crank bolt
Tools for Changing a Chainring
The New Chainring
First, you’ll need to pick up your new chainring(s). The easiest thing to do is to pick up a new version of the chainring that’s on your bike currently, if you can—it’s guaranteed to fit and be compatible with the rest of your drivetrain.
Should I get a different size chainring?
Perhaps you’d like to use this opportunity to make your ride even better by changing the size of your chainring. Chainring size can make a big difference, especially if your bike only runs one, like on singlespeed bikes, track bikes, most modern mountain bikes, and many gravel bikes.
If you find yourself riding in the easiest gears in your cassette most of the time, and often have a hard time turning over the pedals, you should consider a smaller chainring with less ‘teeth.’ If you find yourself riding in the hardest cogs most of the time and frequently spin out, then you might want to consider getting a bigger chainring. Even changing to the next size chainring, up or down, with a difference of just two teeth will feel noticeably different.
If you’d like to get a larger chainring, make sure your front derailleur can accommodate it; review the manufacturer’s specifications, or contact them. Likewise, if you’re going with a different size chainring, bigger or smaller, you’ll likely need to adjust the length of your chain, too.
There are a few other things to keep in mind when getting a different type of chainring, regardless of size. Many chainrings attach to a part called the ‘spider’ which then attaches to (or is integrated into) the crank. (Some manufacturers make direct-mount chainrings that mount directly to the crank arm instead of a spider.) Make sure the new chainring has the correct number of mounting holes, typically four or five, and matches the spider or crank; it will also need to use the correct size bolt circle diameter (BCD).
Regardless, make sure your new chainring is compatible with the rest of your drivetrain.
Removing the Crankset
Depending on your setup, you may be able to remove the chainring(s) without having to remove the crankset. If not, there are many different types of cranksets and, subsequently, ways to remove them. Regardless, first you’ll remove the chain from the chainring, letting it rest on the chainstay.
Self-Extracting
Most cranksets use a crank bolt to secure one or both cranks. If there is a crank bolt on the right crank (with the chainring), remove it counterclockwise with a hex wrench, typically size 8mm. Note, the crank bolt will likely take quite a bit of force and leverage to remove. If there’s a retaining ring over the bolt, keep it in place (and tighten if needed with a pin spanner or larger hex wrench, you want it secure)—you can still remove the bolt, just fit the hex wrench past the ring. There may be a dust cap over the bolt instead, which may or may not need to be removed to access the bolt. If your crank is self-extracting, these are the only steps you’ll need to follow to remove the crank.
Some cranksets only feature a bolt on the left crank. Follow the same instructions above and remove it with a hex wrench. If that’s all that’s needed to remove the left crank, you can now pull out the right crank, which will be attached to the spindle that fits through the bottom bracket. You may need to use a rubber mallet to gently tap the spindle and crank out.
Non-Self-Extracting
If removing the crank bolt does not free either the right or left crank, you have a non-self-extracting setup. You may then need a crank remover—as indicated by internal threading that may now be visible—also called a crank puller, that matches your crank bolt size. Or, once you remove the bolt, you may find either a square taper spindle, an 8-spline spindle, or a 10-spline spindle, and will need the right proprietary tool to remove the crank.
Alternatively, if there are two pinch bolts at the base of the crank, you will need to loosen those first and partly pull out the stop plate from the gap before removing the crank bolt. Some two piece cranks instead have a preload collar that will need to be loosened first.
Lastly, there are other less common variations of cranksets that require different methods of removal, like older Campagnolo cranksets and one-piece cranksets commonly found on older and classic-style bicycles.
Replacing the Chainring
To remove the chainring, you’ll need either a hex wrench (typically size 5mm) or a Torx wrench to remove the bolts—locate the bolts on the back of the chainring and turn counterclockwise to remove. In some crankset styles, the chainring bolts face outside instead and require a tool like a nut wrench tool to hold it in place from behind while you use a hex or Torx wrench to remove it from the front. Again, the bolts may take a bit of force and leverage to remove.
With the chainring(s) off, take this opportunity to wipe down the spider, crank, bolts, and spindle (if attached) with a clean cloth.
To help with correctly positioning the new chainring(s), note the orientation of your old chainring(s) before removing.
To install, line up the bolt holes on the new chainring with those on the crank/spider, position the chain stop pin on the large chainring behind the crank, and make sure any writing is facing out, away from the bike. If you’re also installing a second, smaller chainring, place it on top of the larger chainring, line up the holes and any indicator (orient it behind the crank), with the writing facing in towards the bike. Reinstall the chainring bolts—preferably with threadlocker compound, like Loctite, applied to them—to the recommended torque spec in a star-shaped pattern.
Now, reinstall the crank, carefully ensuring that any splines are correctly lined up. If there is a spindle attached, grease the outside of it and any threads or splines at the end before fitting it through the bottom bracket. Tighten the crank bolt to the recommended torque spec—it will be fairly high, 27 Newton meters or more.
A properly-installed chainring should run smoothly and without creaking. If that isn’t the case, check that all bolts are properly tightened to their recommended torque spec. When in doubt, rely on your local shop mechanic to help you finish the job.
When she’s not out riding her mountain bike, Jessica is an editor for Popular Mechanics. She was previously an editor for Bicycling magazine.
