When was the last time you checked your bicyle chain for wear? Paying attention to its condition and replacing your chain once it’s stretched can save you BIG money.
As chain parts wear out, the chain elongates (or “stretches”) and if you don’t 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 I’m already cleaning and lubing it.
In this article (and video), I’ll walk you through when to replace your chain, and exactly how to check it step by step.
Watch The Video
What You’ll Need
Not much! That’s the beauty of this one.
- Your bike.
- A chain wear indicator tool (also called a chain checker).
You can buy one online and they’re super inexpensive, usually around $10 to $15, so it’s 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. I’ll explain that more in a moment. I have this cheaper one* from Bike Hand but it only shows 75% stretch.
Don’t have a chain checker and don’t want to buy one right this second? No problem. You can get a rough read with a ruler, and I’ll show you how a little further down.
What Do You Mean By Chain Wear?!
When we say we’re checking a chain for wear, what we’re really checking for is stretch.
No, your chain isn’t stretching like a rubber band. What’s 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 that’s 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 doesn’t 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 you’re 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%. (I’d recommend buying one that shows both 50% and 75%).
When your chain gets to around 50% stretch it’s time to think about replacing your chain soon. At 75% stretch, it’s time to replace right away. At 100% stretch, there’s a good chance you’ll have to replace additional parts in addition to your chain.
The more cogs (rings) you have on your cassette, the sooner you’ll 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 Step
- Grab 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 it’s time to think about (or do) a replacement. If the tool sits up on top of the chain and won’t settle in, you’ve 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 Ruler
If you’d rather not buy a tool yet, you can get a decent read with a plain old ruler. It’s less precise, but it’ll tell you if you’re 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: you’re 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 you’re at it.
Is this as accurate as a $10 tool? No. But it works in a pinch and it costs you nothing, so there’s no reason to skip the check just because you don’t own a checker yet.
How Often Should You Check?
I check about once a month, and I usually do it when I’m 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 it’s free.
What To Do If Your Chain Is Worn
Time for a new chain! And here’s 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. That’s how you know it’s probably time to replace them too. (Also not too hard, but more expensive).
Bottom Line
Checking 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 you’ll keep your bike shifting smoothly for a lot longer.
More Stuff You Might Find Helpful
- How To Refresh Tubeless Tire Sealant
- How To Replace Disc Brake Pads On Your Bicycle
- Your Guide To Bike Maintenance
About The Author
Kristen Bonkoski is a USA cycling and NICA coach, bike educator, and founder of Femme Cyclist.
She’s also the host of the Femme Cyclist podcast and runs Rascal Rides, a website about biking with kids.
She’s been riding bikes for more than two decades and is passionate about empowering women on the bike.
IG: @femme_cyclist