How to Replace a Chain

by Pedal Wrencher

Posted: 2016-04-16 at 16:38

When it comes time to replace your chain, you may be thinking, “Well, great, but…how?” Not to worry. Replacing a bicycle chain is actually not a very complicated job at all, especially if you still have the old chain (in other words, if you’re replacing your chain because it’s worn out, not because you’ve had a catastrophic failure while on a ride). In fact, you only need one tool for the job – a bicycle chain tool, pictured below, which you can get at any bicycle shop or through online retailers, too.

Take Off the Old Chain

You’ll use this tool to take your old chain off by driving one of the chain’s pins through it, simply by twisting the handle on the tool clockwise. Once the pin is far enough through the chain that you can “break” it (separate the links), turn the handle of the tool back toward the left until you can disengage it from the chain.

Measure the New Chain

Now, new chains generally come in one standard length. That means that you can’t just throw the new chain on and pedal away. You first need to measure it and “cut” it to length. You can do this in one of two ways: measuring against the old chain or pre-installing it on your bicycle.

Measuring Against the Old Chain

If your old chain isn’t too stretched (a sign of wear and tear), you can just lay the two chains side-by-side and use your chain tool to shorten the new chain (using the same method you used to take the old chain off). If the old chain is stretched, you can still use this method, but just measure a single link shorter. You should also note that if the chain is stretched, your gears may be too worn in to accept a new chain, and you may have to replace them for a smoother ride.

After you’ve cut the new chain to length, follow the same instructions for measuring by pre-installing, but you won’t have to cut the chain, and you can just skip straight to putting it together.

Measuring By Pre-Installing the

To measure by pre-installing the chain, take one end of the chain, place it through the front derailleur and lay it over the smallest front chain ring (gear). Let that end dangle off of the chain ring, and lay the other end over the smallest gear on your cassette or freewheel (the rear gears). Guide it around under the gear, and thread it over the top pulley and under the bottom pulley of your rear derailleur, as you can see in the image above (but be sure to use the smallest gear. That’s an important detail for this measuring method).

Once you have the chain threaded through the derailleur, you’ll have it in a position you never want to be in when you’re riding, but it’s a great way to make sure you have just enough chain length. Pull the two ends of the chain toward one another until you have just a little bit of tension on the rear derailleur but you aren’t stretching it forward. You’ll notice that the chain overlaps itself. This overlap is the excess that you don’t need. Follow the instructions above for breaking/cutting a chain to get rid of that excess with your chain tool.

Putting the Chain Back Together

Now, most new chains will have either a master link (SRAM, Campagnolo) or a master pin (Shimano). With a master link, you’ll just put the two sides of the link on either end of the chain and hook them together. With a master pin, you’ll actually have to make sure that you’ve cut your chain so that the ends complement each other and can fit together in your chain tool.

With one of these chains, you’ll slide the master pin into the chain to hold the end links together, and then you’ll drive it through with the chain tool and break off the end with a pair of pliers. In general, it’s easier to go with a chain that comes with a master link, and you can make sure you get the right one by asking the folks at your local bike shop to help you out – you just need to know how many gears your bike has.

Congratulations, you’ve just replaced your chain! For regular updates on when to perform regular maintenance on your bike, using your mileage on Strava, be sure to sign up for Pedal Wrencher’s free text service. Happy riding! 

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