When was the last time you checked your bicyle chain for wear? Paying attention to its condition and replacing your chain once its stretched can save you BIG money. As chain parts wear out, the chain elongates (or stretches) and if you dont replace it in time, it can wear down your other drivetrain parts with it. The good news? Learning to check your bike chain for wear is one of the EASIEST maintenance tasks out there. Anybody can do it (yes, even you). It takes just a couple minutes, and the only special tool you need costs a few bucks.I check my own chain about once a month, usually while Im already cleaning and lubing it. In this article (and video), Ill walk you through when to replace your chain, and exactly how to check it step by step.Watch The VideoWhat Youll NeedNot much! Thats the beauty of this one.Your bike. A chain wear indicator tool (also called a chain checker). You can buy one online and theyre super inexpensive, usually around $10 to $15, so its a great thing to keep in your maintenance kit. I recommend the Park Tools chain wear indicator* because it measures both 50% and 75% stretch. Ill explain that more in a moment. I have this cheaper one* from Bike Hand but it only shows 75% stretch. Dont have a chain checker and dont want to buy one right this second? No problem. You can get a rough read with a ruler, and Ill show you how a little further down.What Do You Mean By Chain Wear?!When we say were checking a chain for wear, what were really checking for is stretch.No, your chain isnt stretching like a rubber band. Whats actually happening is that the little pins and rollers inside each link slowly wear down as you ride. That wear creates tiny gaps, and multiplied across a hundred-plus links, those gaps add up. The result is a chain thats measurably longer than it was when it was new.A chain wear indicator tool measures that elongation for you.Why This Matters (Hint: Money)A stretched chain doesnt sit cleanly on your cassette cogs and chainrings anymore. Instead of rolling over them cleanly, it starts grinding away at those teeth and wearing THEM out too.If you catch the wear early enough, you just replace the chain (which is relatively inexpensive).Wait too long, and that worn chain will chew up your cassette, your front chain ring, and even your derailleur pulley wheels. Now youre looking at replacing your whole drivetrain, which is EXPENSIVE.Replacing your chain on time is the single easiest way to make everything else last longer. When Should You Replace Your Chain?Most chain checkers give you a reading as a percentage of wear, commonly 50%, 75%, and 100%. (Id recommend buying one that shows both 50% and 75%). When your chain gets to around 50% stretch its time to think about replacing your chain soon. At 75% stretch, its time to replace right away. At 100% stretch, theres a good chance youll have to replace additional parts in addition to your chain. The more cogs (rings) you have on your cassette, the sooner youll want to replace. Those higher-speed chains are narrower and less forgiving of wear, so 10, 11, and 12-speed setups are the ones to really stay on top of, ideally replacing around 50%. You can also look up the exact number that your drivetrain manufacturer recommends replacing at. SRAM and Shimano, for instance, publish the wear spec for each chain.How To Check Your Chain For Wear, Step By StepGrab your chain checker tool and find any spot along the chain to test.Place the little teeth (hook-shaped) at the back of the tool over one of the roller pins.3. Lay the tool down flat onto the chain and let the other end drop toward the chain. The part that drops down into the tool will be labeled 50% or 75%. 4. Read it. If the indicator drops all the way down into the chain, your chain is worn to that percentage and its time to think about (or do) a replacement. If the tool sits up on top of the chain and wont settle in, youve still got some life left.The first image shows that indicator dropping fully into the chain. This chain is ready for replacement. The second image shows the tool sitting on top of the chain; it still has some life left. What did I tell you? Super duper easy.No Chain Checker? Grab A RulerIf youd rather not buy a tool yet, you can get a decent read with a plain old ruler. Its less precise, but itll tell you if youre in trouble.On a new chain, 12 full links measure exactly 12 inches, pin center to pin center. So line up your ruler with the center of one pin at the zero mark and count 12 links down:Bang on 12 inches: youre good.About 12 and 1/16 inches: wear is showing, start planning to replace.12 and 1/8 inches or more: replace it now, and check your cassette while youre at it.Is this as accurate as a $10 tool? No. But it works in a pinch and it costs you nothing, so theres no reason to skip the check just because you dont own a checker yet.How Often Should You Check?I check about once a month, and I usually do it when Im cleaning and lubing my chain already. Ride a lot of miles, or ride in wet and gritty conditions? Grime accelerates wear, so check more often. When in doubt, check. It takes two minutes and its free.What To Do If Your Chain Is WornTime for a new chain! And heres more good news: replacing your chain is another simple maintenance task you can do at home, no bike shop required.If you rode your chain WAY past worn (it happens, no shame), a fresh chain might skip on your other, worn parts. Thats how you know its probably time to replace them too. (Also not too hard, but more expensive). Bottom LineChecking your chain for wear is cheap, fast, and one of the highest-payoff maintenance habits you can build. A basic chain checker costs about the price of a coffee, the check itself takes two minutes, and staying on top of it can save you a couple hundred bucks in drivetrain parts down the road.Check monthly, replace by about 75%, and youll keep your bike shifting smoothly for a lot longer. More Stuff You Might Find HelpfulHow To Refresh Tubeless Tire SealantHow To Replace Disc Brake Pads On Your BicycleYour Guide To Bike MaintenanceAbout 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 Check Your Bike Chain For Wear appeared first on Femme Cyclist.