Your bicycle chain needs to be replaced (its stretched, cracked, or rusted) and youre wondering if you need to take your bike to the shop. You dont.Replacing a bike chain is straightforward, and you only need two tools plus the new chain.For years, I took my bike to the shop for all drivetrain work, but once I started doing it myself and realized just how doable it is, I started teaching others how to do it too. The more you know about your bike and how it works, the more empowered youll feel. In this article, Ill cover when to replace your chain, what tools you need, how to pick the right chain, and the step-by-step.Watch The VideoVisual learner? Watch this video instead.When Should You Replace Your Bike Chain?There are several reasons you might need to replace your chain.The most common is that you measured your chain for wear (aka stretch), and discovered that it is time to put on a new one. If you dont know to do this, read my article on how to check your bike chain for wear. When you replace your chain as soon as it starts to stretch (wear), you prolong the life of the rest of your drivetrain. If you wait too long, youll wear down other drivetrain parts (like your cassette, chain ring, and derraileur pulley wheels) which can be very expensive. The next reason is chain failure of some sort. Sometimes, this means that your chain actually broke and fell off the bike while riding. (Hopefully, you had a tool and masterlink and were able to repair it long enough to get yourself home). It could also mean that you were cleaning your bike and noticed cracked or bent links. In all these cases, its time for a new chain.Finally, if a chain has been neglected for a long time and has heavy rust, it also needs to be replaced. What Youll NeedChain pliers /master link pliers* (I really love the Wolf Tooth Pack Pliers which are small enough for my on-bike tool roll as well as at home repairs).Chain breaker tool *A new chain (see the next section)How To Choose The Right Replacement ChainTo choose the correct replacement chain for your bike, youll want to determine the speed count of your existing drivetrain. If you dont know your speed count, count the number of cogs (rings) on your rear cassette. For instance, if you have 12 rings on your rear cassette, youll want a 12-speed chain. If you have 10 rings on your rear cassette, youll need a 10-speed chain.You also want to make sure to match the brand to your rear derailleur, or make sure its listed as compatible with that rear derailleur. If you watch the above video, youll see I had a SRAM GX derailleur with a 12-speed cassette, so I bought a SRAM GX 12-speed chain. Step 1: Remove The Old ChainBefore we can put on your new chain, we have to remove the old one.To do this, youll want to locate the master link. Its the one link that looks a little different from all the others. Sometimes its a different color, sometimes not, but in all cases, it will have a little slot next to one of the pins. That little space is what allows us to disengage the master link and release the chain.Position your chain pliers on either side of the master link and squeeze inward to release.Before you pull the chain off the bike, you may want to snap a photo. I like to take a picture of how the chain routes through the rear derailleur pulleys in case I have any questions later. (This is a good habit for all bike maintenance work in the beginning as you start to learn). Step 2: Determine The Correct Length For Your New ChainWhen you pull your new chain out of the box it will be longer than you actually need it to be.Well use the old chain to inform how long our new chain to be. That said, you cant just match the two by length because the old chain has stretched over time.Instead, you need to match the NUMBER of length on the new chain to the number of lengths on the old chain. There are two ways you can do this.Method A: You can manually count the outer links on the old chain, and then count out the same number of outer links on the new one.Method B (easier): Lay the two chains side by side, matching one outer link on the old chain to one outer link on the new chain.In either case, make sure you start with the master link on each chain and count it as one outer link.Once youve matched the number of outer links, go to the next outer link on the new chain and mark the first pin with a sharpie. Thats where youre going to break the chain. Step 3: Break The New Chain To LengthGrab your chain breaker tool and place the marked link in the chain breaker with the first pin lined up with the pin on the tool. Screw the tool in until you hear and feel the chain break. (It will take muscle and might feel a little scary. Keep going, you can do it!).Once it breaks, keep screwing until you push the pin all of the way out.Then, back the tool out and remove the extra links. Your chain is now the correct size. Go ahead and place the second half of your new master link into the new hole where you just pushed out the pin.Step 4: Route The New ChainRoute the chain onto the bike making sure that it matches your photo. It will go over the front chain ring, onto the rear cassette, then through the derailleur (under the top pulley wheel, over the bottom pulley wheel).Step 5: Connect The Master LinkOnce you have the chain over the front chain ring and thru the derailleur, bring two ends together at the bottom run of chain and join the master link. If your masterlink has an arrow, make sure its pointing in the direction the chain will move. When the masterlink is at the bottom of the chain, that means the arrow will be pointing backward toward the rear derraileur. Make sure you get both pins thru the little slots on the front and back of the masterlink (squeeze them together), and then give the chain a little pull to help it engage. Put the chain pliers on either side of the master link, and this time pull them apart to pop the link fully into place. If you struggle to get it fully engaged, go give it a couple hard pedal strokes which will usually do the job for you. Troubleshooting: My Chain Is Skipping After Replacing ItIf, on your first ride after replacing your chain, your chain is skipping, it means that other drivetrain parts are worn and need replacing as well.Start with the cassette, but make sure to check your front chain ring(s) and derailleur pulley wheels as well. Other Articles You Might Find HelpfulYour Guide To Bike MaintenanceHow to Clean and Lube Your Bike Chain (Its Easy!)How To Refresh Tubeless Tire SealantAbout The AuthorKristen Bonkoski is a USA cycling and NICA coach, bike educator, and founder of Femme Cyclist.Shes also the host of the Femme Cyclist podcast and runsRascal Rides, a website about biking with kids.Shes been riding bikes for more than two decades and is passionate about empowering women on the bike.IG:@femme_cyclistJoin Kristens Weekly Newsletter!The post How To Replace A Bicycle Chain appeared first on Femme Cyclist.