The Bike chain. Probably the most important component on your bike, and the one cyclists concern themselves with the least. A chain is a succession of simple components joined to not come apart, even when you apply all your strength to the pedals.

Keeping your chain clean and lubricated extends its life, but it eventually wears out. How? The metal rivets rub against the grooves in between the chainring teeth. These are the same grooves and ramps that make shifting smooth and efficient. This friction reduces the diameter of the links over time, giving the impression of a stretched chain.

A worn bicycle chain can break at the worst possible moment. Be proactive about replacing your chain rather than allowing the wear to go too far and having it interrupt your ride.

You can take out a link to shorten it, but eventually, chain wear reaches a point where it may break. Hopefully, you’re not out on the trail if and when it happens. But if you are, you can still salvage it—at least enough to get you home—using the techniques in this article.

When to Replace a Bike Chain

Don’t wait for your chain to fail before replacing it. You’re less likely to damage or wear out costly components if you monitor your chain wear and replace it when required. Knowing when to replace your chain is broken down into specific stages of wear, but there’s a bit of educated guesswork involved too.

Factors such as dirt, lubrication, rider weight, and riding style impact chain wear. You can’t predict how many miles you can ride before your chain stretches and requires replacement. You can use a ruler to measure how much elongation has occurred, but measuring these micro differences is tricky.

Luckily, we can use a chain checker gauge instead. Versions of this tool vary in price, but basic models sell for about $12. How do they work? Notches on the tool that represent certain percentage limits slip in between the links of your chain. If the gauge fits easily into the chain at your recommended max percentage, it’s time to replace it.

Any 12 links in a chain should measure 12 inches across. Chain manufacturers recommend replacing your chain once it reaches a certain percentage of elongation between links. For 9 and 10-speed chains, it’s 0.75% wear; and 0.5% for 11 and 12-speed chains.

If you don’t have a chain checker, you can still measure by eye. To do this, put your chain on the large front chainring and lift the chain off around the middle of the ring. If it lifts off more than the height of half a tooth on your ring, your chain is worn and needs replacing.

Parts of a Chain

Before you replace your chain, it’s important to know what parts go into making one. Each link of a chain has four different parts: Outer Plates, Inner Plates, Rollers, and Rivets. The rivet fits through each of the other components to form a link. Repeat this up to 116 more times (depending on what type of chain you have), and you’ve got a bike chain. Let’s move on to how to replace your chain.

Breaking Your Chain

To replace a chain, you need to break it first. And for that, you need a chain-breaking tool. They’re not very expensive and make the process easy. I recommend the ratcheting multi-tool from Blackburn.

Start by breaking and removing the old chain. It's best to do this with the bike on a repair stand or lean it against a wall. There is no need to remove the wheels. And don’t throw out the old one yet, you need it to size the new chain.

Step One

Seat the chain on the chain tool on the notches furthest away from the lever that turns and controls the push pin. Turn the lever until the push pin almost touches the chain. Line the push pin up with a rivet in the chain link and turn the lever to push the rivet through the inner plate and roller. It takes a good amount of initial force to start the process.

Step Two

If you ever plan on reusing your chain, don’t push the pin all the way out the other side; they’re almost impossible to get back in. The rivet only has to be pushed out far enough to break the chain.

Step Three

Flex the chain just enough to separate the links. Remove it from the bike, and set it aside. A note about different brands’ bicycle chains: Shimano rivets aren’t reusable, instead they have a proprietary connecting pin system. Their rivets and connecting pins are the exact sizes of the holes in the plates they fit into, so you may occasionally need a Shimano-specific chain tool.

SRAM connects their chains via a “Powerlink”. It requires no special tools to break or connect the chain. Instead, you push the links on either side of the Powerlink toward each other to open the connection, or apart to close the link. This is easy if you have three hands, but as that doesn’t apply to the majority of us, you’ll need to exercise some patience. Continue working to separate the master-type link or treat yourself to a pair of master link pliers for stubborn ones.

Installing a New Chain

Your replacement chain should be the same number of speeds as your bicycle. A 12-speed bike needs a 12-speed chain. If you aren’t sure, count the number of cogs on your rear cassette, visit your local bike shop. Shimano chains are unidirectional, meaning they have to run in a specific direction. Read the included paperwork to determine the correct orientation. KMC and SRAM chains are not direction specific.

Once you have the right chain, it’s time to make it the same length as your old one before you install it. Lay the two chains side by side, lining up the links. Remove any excess links on the new chain with your chain tool, making sure the opposing ends connect correctly according to your system, whether it’s a master-type link or a connecting pin. Keep extra links to fine-tune your chain to the right length if necessary. Both master links and connecting pins are usually packaged separately in the box with the chain, so don’t throw it out by accident.

Step One

Route the chain around the chainrings and through the rear derailleur (in the right direction if required!). Pull each end of the chain together and connect them with a master-type link or a connecting pin. If trying to reuse the old rivet, attach the ends and use the chain tool in the opposite direction to push the rivet back into place.

Step Two

Once reconnected, make sure everything works correctly. A stiff link can be moved back and forth to loosen it. That’s it!

Your chain may have come pre-lubed, but it’s a good idea to wipe off any dust or debris and add some fresh lube to your chain and let it soak in before you ride.

If you plan on using a ceramic-based lube, completely clean the chain of its factory treatment before applying the ceramic stuff. Applying it on top of any other lube is just a waste of product.

To explore more Cycling articles as you pursue your journey in the sport, check out the Expert Journal here on Curated.