Should you check your chain?

Bicycle chain links are a half inch long from rivet to rivet. When you measure a brand new chain with a ruler, the rivets should all line up exactly on the inch and half inch marks. With use, the chains “stretch” so that the rivets no longer line up over the length of a ruler.

Chains don’t really “stretch” — the insides of the chain wear with use, resulting in parts with more play and an elongation of a length of chain. You measure chain wear (or stretch) by lining the chain against a ruler. Because the links are exactly 1/2 inch long, the measure from rivet to rivet should be on 1/2 inch increments.

You can see in this photo that the top, older chain has about a 1/16″ of wear at one foot. The bottom chain is a brand new, unused 10 speed chain. Click on the photo to see large if you want.

Chain Stretch

It’s not necessary to remove the chain to measure it — just line a ruler up along a straight part of a chain and measure from the middle of a rivet. If you see more than about 1/16th inch of wear along a six inch segment of chain, it’s a good idea to replace the chain. There are also chain wear measuring tools where you pop the tool on the chain to quickly and easily determine if your chain is worn.

Why should I change the chain?

Chain wear is important mostly for bicycles with rear derailleurs. Excessive wear leads to poor shifting, and worn chains increases wear on your cogs which makes shifting even worse.

You can get away with a little more chain wear on your singlespeeds, fixed gear bikes and bikes with hub gears. First of all, you can use beefier — and less expensive — chains. Derailleur shifting performance is not an issue, so worn cog teeth aren’t too big of a deal. When the teeth start to get the shark fin look like on the cog below, though, it’s past time to replace your chain and cog.

Coming later: How to replace your chain.

Photo credits: Chain measure photo by Richard Masoner; Worn cog photo by Jason Rogers.

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0 thoughts on “Should you check your chain?”

  1. Worn chain – I know that pain! I thought I was measuring my chain wear well on my Sturdy Commuting Bike, but it turns out that either it ‘suddenly’ just wore away, or I wasn’t measuring it right. The result was that on a fairly inexpensive bike, the cost of parts that needed replacing was more than the cost of replacing the bike. Not that I’m going like-for-like on the replacement!

    You can also get really handy tools for checking chain wear. These are basically go / no-go gauges that you fit between several links. If the tool goes in one way, the chain’s OK, but if you can flip it over & fit it in the other way, it’s time to replace it.

  2. Paul in Minneapolis says:

    I like to have 2 to 3 chains for each bike. When a chain gets dirty, and there is not time to clean, I just swap chians and clean later. By keeping my chains clean, they last much longer.
    If you user SRAM chains with the quick link, carry and extra link with you. I have had them come off while riding.

  3. electric says:

    Yes, please measure and replace…

  4. Ralphy says:

    So how much longer can I leave my chain on my singlespeed (KMC Kool chain)? I was replacing at 0.75% wear but is that too often?

  5. Psycho says:

    I’d be concerned if you’re replacing your chain at every 0.75% of wear… it’s still got 99.25% left! 😉

    To be fair though, I over-wear my chain, to the point where I can reef the chain through the cogs on an initial power stroke. So I have to change chain and cogs at the same time. By changing the chain more often, I could save myself wear and tear (and money) on the rear cogs.

  6. Wolfy says:

    I had an SS chain break the other day, but I was able to ride it for a WHILE with one side of one link snapped. It is a Pintle or Half Link Chain. People tell me all the time to get a lighter road chain and it’ll be strong enough. But to hell with that. Big chain means you can probably get home even if it breaks!


  7. electric says:

    Not an engineer, but, stainless steel is typically softer than your normal carbon steel which will cause it to yield(bend and thus break your chain) at a lower force. As for rust eating away your chain… I’m not so sure if it’s an issue as your chain will most likely get destroyed by fine grit used to combat icy roads before you need to consider rust? In fact usually chains are plated with zinc but i’m pretty sure it adds nothing much except some extra “bling”

    I was going stainless steel, but nothing was readily available and so far so good.

    As far as wide chains.. it’s not true that bigger is always better. I’ve heard of those fat chains have poorer build quality compared your sram/shimano chains. Although beefy chains seem burly and tough not all the pieces will be have assembled together nicely. After all, a chain is only as good as it’s weakest link 🙂

    Big chains are great for one thing, combating dirt/grit/ice induced chain-suck!

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