Bike Maintenance: How to Replace a Bike Chain

All bike chains wear with time. To keep your components in good shape, you’ll need to replace your chain periodically. In this video, we show you how to remove your old chain, insert a new chain, size the chain and connect the new chain. Shop REI’s selection of bike chains at http://www.rei.com/c/bike-chains.

Video Transcript

Of all the components on your bike, the chain needs to be replaced most often. To keep a stretched chained from wearing down your other components, you'll have to replace it periodically.

When you're buying a new chain, make sure it matches the speed of your cassette. For example: a ten speed chain will only work with a ten speed cassette. All you'll need is a chain tool, but a pair of master link pliers may come in handy.

If your rear derailleur has a clutch, turn it off. Then shift the chain to the smallest chain ring and the smallest cog. If you have a shimano chain, use a chain breaking tool to push a pin part way out of the lower section of chain until you can separate the links. You'll know it's a Shimano chain if it says HG somewhere on the links. For SRAM chains, find the master link and push the two plates together to unlock it. You can do this by hand, or with the pair of master link pliers. Before you remove the chain, note how it passes through the rear derailleur. It may be helpful to take a picture to remind yourself later. Now you can remove the chain and set it aside.

If you have a Shimano chain and there's only lettering on one side, make sure it's facing out, away from the bike. Thread the new chain through the front derailleur and onto the smallest chain ring. Spin the pedal slightly to make sure there are a few inches of chain handing below the crank set. Thread the other side of the chain through the rear derailleur. This can be a tricky process, so take your time to get it right.

Start by making sure that both derailleurs are shifted to the smallest chain ring and smallest cog. Bring the two ends together to form a straight line between the chain rings and the derailleur. With not tension on the chain, the tensioning arm will fold up against the cassette. Pull slack out of the left side of the chain until there's a gap between the arm and the cassette. You want to create the smallest gap possible that still lets you connect links. It's important to note that to connect a sShimano chain, you need to wide outer plate and a thin inner plate. SRAM chains need two inner plates. Once you have the arm in the right spot, note where the chain overlaps. This is where you'll need to break it. Now you can break the chain and set the extra links aside.

To connect a Shimano chain, bring the two ends together. You can use a piece of stuff wire to hold it as you work. Insert a pin and push into place with your chain tool. Once it's through, break off the end of the pin with a pair of pliers or a chain tool. Then wiggle the links to make sure they're not too stiff and they rotate smoothly around the new pin. For SRAM chains, place one half of the master link onto each end of the chain. Bring the links together, slot the pins through the holes in the link, and pull it tight. You want to make sure the plates are fully seated, so hold the rear brake to lock the wheel, and push down on the pedal. You should see the plates pop into place. Again, wiggle the new link to make sure it rotates smoothly. If your derailleur has a clutch, make sure to reengage it. Finish by spinning the pedals and making sure the gears shift normally. Test every gear combination and make sure the chain is long enough to be on the biggest cog and the biggest chain ring at the same time.

To recap:
Break the chain and take it off the bike.
Thread the new chain through the derailleurs.
Use the tensioning arm to help you size the chain.
Connect the two ends and make sure you can shift through every gear.