Learning how to replace a bike chain is a pretty important skill for all bike owners. The chain, after all, is probably one of the things you have to change or repair most often (besides your tires). And if you wait too long, and your chain wears out, it could diminish your shifting quality and shorten the lifespan of the rest of your drivetrain components.

So, to keep your bike healthy and your rides strong, here’s your guide to bike chain replacement, including when and how to fix it, whether you’re at home or on the road.

When to replace your bike chain

How often should you replace your chain? Before answering that question, it helps to understand the process of chain wear. As your chain ages, each link’s internal bushings slowly lengthen. In turn, your now-longer chain puts added pressure on your cassette cogs and chainring teeth, causing them to wear faster. This also hampers shifting quality.

The 2,000-Mile Rule

To avoid this accelerated wear of your cassette and chainrings, a general rule of thumb is to replace your bike’s chain every 2,000 miles. Mind you, this is just a starting point. No two chains will wear at exactly the same rate because no two riders treat their chains the same.

If you’re the type who spins easy gears, meticulously cleans and lubes the chain after every ride, never rides in the rain, and weighs as much as a WorldTour climbing specialist, your chain is likely to last longer than 2,000 miles. But if you love to push big gears, ride rain or shine all the time, and don’t even own shop rags, getting over 2,000 miles out of your chain is likely a pipe dream.

how to replace a bike chain
Trevor Raab

These differences in riding style are why it is best to periodically use a chain wear measuring tool to determine the condition of your chain. With the tool in hand, apply pressure to a pedal so the top of the chain is taut, and then place the measuring tool in place on the chain as shown in the video above and read the results. Indicators on the tool will tell you whether it’s time to replace your chain.

The Ruler Test

You can also measure chain wear using a standard ruler. To do this, you should know that all modern chains have rivets every half-inch, and that you will be measuring from one rivet to another one that is 12 inches away.

how to replace a bike chain
Trevor Raab

Start by drawing the chain taut. Align the end of the ruler at the zero-inch mark with the center of a rivet, and then see where the ruler’s 12-inch mark lines up. If it is dead center on a rivet, the chain is in great condition. If the rivet is less than a 1/16 of an inch ahead of the 12-inch mark, then the chain is showing some wear but still has plenty of life left in it. If the rivet is more than 1/16 of an inch ahead of the 12-inch mark, then it’s time to replace your bike chain.

Pro tip: If you’ve replaced your chain once or twice before, you’re probably due to replace your cassette and/or chainring(s) as well. This is especially true if you experience skipping with your new chain.

How to fix or replace your bike chain

Cutting a new bike chain to the correct length for installation and removing a damaged link for an on-trail chain repair are essentially the same job. Make life easier by using a full-size tool at home, and save the compact tool for midride fixes.

To start, you’ll need to pick up the right size chain for your bike. We’re not talking about the length of the chain here (you’ll address that later), but width. This is dictated by the number of cogs on your cassette; a 6-speed bike uses the same width chain as an 8-speed, but a 9-speed needs something different, and so on. (Check out Park Tool’s chain compatibility guide for more on this.) The easiest way to ensure you get the right chain is to buy the same kind of chain that came on your bike. If you decide to go with a different chain, it’s best to get one from the same manufacturer.

Next, you’ll need a chain breaker tool, or chain master link pliers if your chain has a master link. Line up the chain on the smallest rear cog and largest chainring (if you have more than one) to make installing the new chain easier.

4 Tools to Replace Your Chain
Universal Chain Tool
Topeak Universal Chain Tool
Now 21% Off
$14 at Amazon
Credit: Topeak
Chain Checker Tool
Park Tool Chain Checker Tool
Credit: Park Tool
Bicycle Chain Master Link Pliers
Park Tool Bicycle Chain Master Link Pliers
Now 14% Off
Credit: Park Tool
M19 Multi-Tool, with Universal Chain Tool
Crankbrothers M19 Multi-Tool, with Universal Chain Tool
Credit: Crankbrothers

If your chain has a master link—which is common, so be sure to check—like a Shimano Quick Link or SRAM PowerLock, use a pair of master link pliers to compress the link and undo it. (If it’s a newer chain, you might be able to do this with your hands.)

chain sizing
You can size your new chain based on the old chain you removed from the bike.
Trevor Raab

If there isn’t a master link, remove the chain using the chain breaker tool. Back out the tool’s pin to make room and fit a chain link into the outer slot, and line up the tool’s pin with a pin on the chain. Tighten the tool until its pin puts light pressure on the chain’s connecting pin. Crank the handle, making sure the tool’s pin stays straight. If it twists, stop and realign everything so as not to bend the tool’s pin. If you bend it, most tools have replaceable pins available; some even come with one inside the handle. Then push the pin far enough through so you can remove the extra links.

Remove the chain from your bike. Then, measure out the length of your new chain to match the length of your old chain, taking into account the master link. Remove any excess links from the new chain using the chain breaker tool, and install the master link. Thread the new chain onto your bike’s cassette and chainring and connect the ends with the master link, making sure the link is secure and locked in place.

sizing chain
Sizing a new chain
Trevor Raab
fixing chain
Connect the quick link 
Trevor Raab

How to fix a chain on the go

If your chain breaks midride, use your multitool’s chain breaker to remove the damaged link. If you don’t carry extra chain link pins, you can use an existing pin to reconnect the chain. Just don’t drive it out completely (the mushroomed end of the pin gets rounded off upon removal); leave it in one side plate. The connection will be weak and the chain will be shorter, so pedal home gingerly and replace the damaged chain before your next ride.

Headshot of Jessica Coulon
Jessica Coulon
Service and News Editor

When she’s not out riding her mountain bike, Jessica is an editor for Popular Mechanics. She was previously an editor for Bicycling magazine.