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Do you need a new chain? Find out the easy way to tell

A worn chain can wreak havoc on the rest of your transmission. Read our expert guide to learn how to tell that it's time for a new one

Your bike chain will gradually wear with use and will need changing from time to time in order to maintain your drivetrain’s performance. Worn chains shift poorly, wear sprockets quickly, and sometimes break. 

So when should you change your chain?

“For chain replacement we do not state 'every x kms' as this is not possible,” says SRAM. “Chain wear is based on multiple factors including maintenance (clean/lube), use conditions (water/mud/sand), user shifting patterns and overall drivetrain condition (cassette/ chainring wear).”

Cross-chaining: is it really all that bad?

Campagnolo agrees.

“It is difficult to pin down an exact number to kilometres due to the fact that riders come in different weights and sizes, ride differently, shift more or less frequently, develop more or less wattage, ride on flat or hilly terrain, clean or nasty conditions, take care or leave their chain dirty… all of which create large variables in just how much wear and tear is created,” says Campag's Joshua Riddle.

“It can vary between 3,000km to 8,000km generally speaking, but it could be less or even more in some cases.”

KMC X10.93 Chain

First, you need to replace your chain when you spot any damage (a deformation or crack). You should also check your chain regularly to see if it has worn to the point that you need to change it. 

There are several ways to check whether your chain has reached this stage?

Measuring with a ruler

You can check for chain wear with a ruler. It’s a little easier if you go with imperial measurement here because one complete chain link of a standard chain measures 1in.

Start at one link pin and measure 12 complete links. You need to put some tension on the chain to be accurate.

Chain Checking inches - 1.jpg

On a standard new chain, 12 complete links will measure 12in, but when a chain is worn the 12in mark of the ruler won’t quite reach the relevant link pin.

If the distance from the 12in mark to the centre of the link pin is less than 1/16in, your chain is fine, but if it gets to 1/8in (or 2/16) mark it has gone beyond the point at which it needs replacing.

If you use metric measurements, it’s easiest to measure 10 links.

Chain Checking cm - 1.jpg

On a standard new chain, 10 complete links will measure 25.4cm.

If the distance from the centre of one link pin to the centre of the link pin 10 complete chain links away is up to 25.5cm, your chain is fine, but if it gets to the 25.6cm mark it has gone beyond the point at which it needs replacing.

If you want to get more accurate, it's usually advised that you replace chain designed for 10 or fewer gears when it has lengthened by 0.75% – so when 10 links measures 25.59cm – and that an 11-speed or 12-speed chain is replaced when it has lengthened by 0.5% – so when 10 links measures 25.53cm. 

If you have a one-speed or two-speed bike, replace your chain as it reaches 1% wear - so when 10 links measures 25.65cm.

Figures like these are obviously very difficult to gauge with a normal ruler, which is why we'd advise the use of a chain wear indicator.

Chain wear indicator

A chain wear indicator, sometimes called a chain checker, is an inexpensive gauge that does exactly what its name suggests. 

Park Tool Chain Checker - 1.jpg

This is Park Tool’s CC-3.2 chain checker with an RRP of £9.99, although you’ll find it cheaper if you look around. Other brands offer similar instruments.

You hook the curved end into the chain and if the gauge tip on the other end fits completely into a chain link, the chain is worn to the point it needs replacing (one side measures 0.5% wear, the other side measures 0.75% wear). 

Measuring by eye

There’s one other simple method of checking for chain wear. 

Chain Checking by hand - 1.jpg

KMC advises, “If you do not have a gauge to test the chain’s elongation you could roughly check by putting the chain on the outer chainring and lifting up the chain from the middle of the chainring. If you can lift it more than half a link, the chain or chainring, or both, are probably worn.”

The chain in the picture is almost new so minimal lift from the chainring is possible.

Check out our advice on how to replace a chain. 

Mat has been in cycling media since 1996, on titles including BikeRadar, Total Bike, Total Mountain Bike, What Mountain Bike and Mountain Biking UK, and he has been editor of 220 Triathlon and Cycling Plus. Mat has been road.cc technical editor for over a decade, testing bikes, fettling the latest kit, and trying out the most up-to-the-minute clothing. We send him off around the world to get all the news from launches and shows too. He has won his category in Ironman UK 70.3 and finished on the podium in both marathons he has run. Mat is a Cambridge graduate who did a post-grad in magazine journalism, and he is a winner of the Cycling Media Award for Specialist Online Writer. Now over 50, he's riding road and gravel bikes most days for fun and fitness rather than training for competitions.

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73 comments

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TucsonGuy | 3 years ago
0 likes

Doesn't KMC make all of Shimano's chains? 

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rayjay | 3 years ago
0 likes

I was using Y BAN ,KMC gold but now switched to black chains 

black are the new gold ...both bikes sub 4 ,kilo . 

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HLaB | 4 years ago
0 likes

I gave up on the tool as I found it way premature for me.  Typically  at 1,500 miles it would say I needed a new chain.  I found in reality I'd get 3x that without the new chain skipping on the cassette.  I usually only think about replacing a chain now if its done 3500-4000 miles.

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srchar | 4 years ago
13 likes

I find it's best to replace my chain whenever this article is republished.

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FrankH replied to srchar | 3 years ago
2 likes
srchar wrote:

I find it's best to replace my chain whenever this article is republished.

It's here again, time to replace your chain.  1

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Yorkshire wallet | 5 years ago
0 likes

Having just returned from Hong Kong, I would say 'never' is the answer. That also goes for lubing your chain. 

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ktache | 6 years ago
3 likes

Fair point john1967 and I cannot fault your arguement, but you do realise this is a website entirely for us cycling suckers.

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davel replied to ktache | 6 years ago
2 likes
ktache wrote:

Fair point john1967 and I cannot fault your arguement, but you do realise this is a website entirely for us cycling suckers.

I find his argument extremely interesting.

What's the implication... 7 years of daily commuting has to be worth, what: 14k - 42kish miles.

You're getting that sort of mileage out of one chain, John?

You should market that 3 in 1 stuff... Honest John's No Sucker Chain Miracle.

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john1967 | 6 years ago
0 likes

had the same chain on me mountain bike for 7 years and use it for commuting every day. Its gets semi regular coatings of house hold 3 in 1 oil and i have absolutely no intention of changing it as i am not a cycling sucker.

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srchar replied to john1967 | 6 years ago
3 likes
john1967 wrote:

had the same chain on me mountain bike for 7 years and use it for commuting every day. Its gets semi regular coatings of house hold 3 in 1 oil and i have absolutely no intention of changing it as I spend all my time on moneysavingexpert.com

So, you're just going to wait until it snaps (which it will, at some point) before you replace it?  Do let us know whether you merely smack your balls into your headset, or have a proper crash and lose some teeth, when that happens.

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madcarew replied to srchar | 6 years ago
0 likes
srchar wrote:
john1967 wrote:

had the same chain on me mountain bike for 7 years and use it for commuting every day. Its gets semi regular coatings of house hold 3 in 1 oil and i have absolutely no intention of changing it as I spend all my time on moneysavingexpert.com

So, you're just going to wait until it snaps (which it will, at some point) before you replace it?  Do let us know whether you merely smack your balls into your headset, or have a proper crash and lose some teeth, when that happens.

In my experience, with derailleur gears, the gears stop working well before the point a chain snaps. Plenty of people use bikes for many many years without changing chains, and with few injuries reported from chain snapping. I have a friend who is 120kg and races. His chains wear pretty badly, but he has found that it's more cost effective to run a chain for 18 months - 2 years (15000 + miles) and then replace his 105 chainrings and sprockets and chain all in one shot than pay for a new chain every 1000 - 1200 miles which was what he was doing before. Personally I change my chain ever 2000 miles or so, because I race and prefer faultless, quiet running gears.

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ConcordeCX replied to john1967 | 6 years ago
4 likes
john1967 wrote:

had the same chain on me mountain bike for 7 years and use it for commuting every day. Its gets semi regular coatings of house hold 3 in 1 oil and i have absolutely no intention of changing it as i am not a cycling sucker.

well done that man! I like the cut of your jib. I've been using the same sheet of toilet paper (the crinkly stuff - it washes better) for just as long.

Waste not, want not!

 

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Karbon Kev replied to john1967 | 3 years ago
0 likes

I agree with your choice of oil, but not with wear of chain.

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nbrus | 6 years ago
0 likes

I have a friend who used old motor oil to lube his chain. He never cleaned his chain and he ran it until it 'looked' worn out (loose and floppy). When he eventually did get around to replacing the chain he found that it skipped on the rear cassette and that only a single link was mating with the front chainring ... he had worn out his drivetrain on a single chain that had lasted only 500 miles (estimated). He has since replaced his worn drivetrain and is now looking after his chain using a good wax dry lube. The bike was an old hybrid, though he does have a race bike that was also treated with neglect, but wasn't used as much, so is still ok. Dirt can quickly grind down your chain and wear out your drivetrain if you let it.

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Jack Osbourne snr | 6 years ago
3 likes

Recently, I deliberately ran a chain for a full year of commuting and after the chain wear indicator hit 1.0, I was able to measure the knock-on effect by the change in shape of chainring teeth. It was dramatic.
Don't underestimate how much damage a worn chain will do to the more expensive bits of your drive train.
Got nearly 4000 miles out of the chain, but the chainrings will need replaced at about 60% of normal lifespan and I got a similarly reduced life from the cassette that was fitted.

For commuting, I'll generally buy whatever is cheapest but really like Ultegra and KMC X10. Currently running a SRAM 1030. Normally, a chain will last me about 6 months/1800 miles with minimal upkeep. I run for 3 months before I start measuring wear.
On the fun bikes, I use Campag and KMC with the Ti-N coating.
ALL my chains, regardless of brand are connected using KMC missing links.

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gmrza replied to Jack Osbourne snr | 6 years ago
1 like
Jack Osbourne snr wrote:

Recently, I deliberately ran a chain for a full year of commuting and after the chain wear indicator hit 1.0, I was able to measure the knock-on effect by the change in shape of chainring teeth. It was dramatic. Don't underestimate how much damage a worn chain will do to the more expensive bits of your drive train. Got nearly 4000 miles out of the chain, but the chainrings will need replaced at about 60% of normal lifespan and I got a similarly reduced life from the cassette that was fitted. For commuting, I'll generally buy whatever is cheapest but really like Ultegra and KMC X10. Currently running a SRAM 1030. Normally, a chain will last me about 6 months/1800 miles with minimal upkeep. I run for 3 months before I start measuring wear. On the fun bikes, I use Campag and KMC with the Ti-N coating. ALL my chains, regardless of brand are connected using KMC missing links.

You've touched on the point that most people forget: chainrings, especially modern ones can be very expensive, especially compared to a chain.

I normally start checking my chains at every change-over after about 3000km.  For commuting, 3000km to 4500km is typical.  On my commuter, I run a 3 chain rotation, with the two that are in storage kept in kerosene to prevent rusting.

For my weekend bike I work on the basis of replacing the chain when I reach 5000km or the chain wears out - whichever comes sooner - that means I replace the chains at 5000km, but the result is that after 15000km the cassette is still in very good condition and the chainrings are not really showing much wear.

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Anthony.C | 6 years ago
0 likes

The point is the tools guarantee inaccuracy as they force the rollers apart and roller wear does not affect chain spacing and so shouldn't be included in the measurement.  Only pin/bushing wear affects chain spacing and performance. I use one myself but only consider replacing the chain when it drops in fairly easily on 1% if I can't be bothered measuring properly. 

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madcarew replied to Anthony.C | 6 years ago
3 likes
Anthony.C wrote:

The point is the tools guarantee inaccuracy as they force the rollers apart and roller wear does not affect chain spacing and so shouldn't be included in the measurement.  Only pin/bushing wear affects chain spacing and performance. I use one myself but only consider replacing the chain when it drops in fairly easily on 1% if I can't be bothered measuring properly. 

But roller / bush wear does affect chain spacing. It is the only thing on your chain that wears. The links don't stretch. If the rollers are worn away inside (or outside) the distance between surfaces that the sprocket or chainwheel teeth catch on are further apart, and so cause wear on the teeth. Both methods, correctly applied will come up with pretty much the same answer. The vast majority of wear is on the inside of the rollers against the bushings and where the pins go through the links as that's where the grease / oil traps the grit and dirt and then the 2 surfaces grind against each other, whereas the interface with the teeth is largely static. 

The 'accuracy' that you talk about is trying to accurately measure an unknown / arbitrary number. We know that chains should be changed at about .75 - 1% wear (33% tolerance in measurement) to reduce drive train wear. This is just a guide number, and if either measuring method is within 10% (i.e. .825 - 1.1%) it still achieves the desired goal of picking a point of wear that is not too extreme but allows a reasonable life for the chain. 

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Anthony.C replied to madcarew | 6 years ago
0 likes
madcarew wrote:
Anthony.C wrote:

The point is the tools guarantee inaccuracy as they force the rollers apart and roller wear does not affect chain spacing and so shouldn't be included in the measurement.  Only pin/bushing wear affects chain spacing and performance. I use one myself but only consider replacing the chain when it drops in fairly easily on 1% if I can't be bothered measuring properly. 

But roller / bush wear does affect chain spacing. It is the only thing on your chain that wears. The links don't stretch. If the rollers are worn away inside (or outside) the distance between surfaces that the sprocket or chainwheel teeth catch on are further apart, and so cause wear on the teeth. Both methods, correctly applied will come up with pretty much the same answer. The vast majority of wear is on the inside of the rollers against the bushings and where the pins go through the links as that's where the grease / oil traps the grit and dirt and then the 2 surfaces grind against each other, whereas the interface with the teeth is largely static. 

The 'accuracy' that you talk about is trying to accurately measure an unknown / arbitrary number. We know that chains should be changed at about .75 - 1% wear (33% tolerance in measurement) to reduce drive train wear. This is just a guide number, and if either measuring method is within 10% (i.e. .825 - 1.1%) it still achieves the desired goal of picking a point of wear that is not too extreme but allows a reasonable life for the chain. 

This explains better than me why roller/bushing wear does not really affect spacing. http://pardo.net/bike/pic/fail-004/000.html 

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hawkinspeter replied to Anthony.C | 6 years ago
2 likes
Anthony.C wrote:

This explains better than me why roller/bushing wear does not really affect spacing. http://pardo.net/bike/pic/fail-004/000.html

Thanks for that - a most informative link.

However, I suspect that roller wear is going to happen at more or less the same rate as bushing/pin wear, so I doubt that the margin of error for chain wear tools is going to be that much of a problem. I'm going to carry on using mine as it's a lot easier to use than a ruler.

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nbrus replied to Anthony.C | 6 years ago
0 likes
Anthony.C wrote:

This explains better than me why roller/bushing wear does not really affect spacing. http://pardo.net/bike/pic/fail-004/000.html 

And from that article...

Using a ruler can be error-prone because it is necessary to hold the ruler precisely and measure one end while making sure the other does not slip. For that reason, several companies have developed chain wear measuring tools. The advantage of a special-purpose tool is that it is faster to measure wear.

Unfortunately, as of 2009/10 only one commercial bike chain wear measures just pin wear. The usual approach is to spread several links of chain by pushing the rollers apart. However, roller wear is added to the measurement, even though it does not affect proper chain operation. The one exception is the Shimano TL-CN40/TL-CN41, which measures only pin wear.

If a tool is conservative, chains are reported as worn-out when they still have useful service life, which increases chain costs. If a tool is not conservative, then errors mean a worn chain can be reported as good, gets used too long, and leads to drivetrain damage.

Commercial tools are conservative and never report a chain as good when it is actually worn. They may, however, report a good chain as worn, leading to increased chain costs.

You may draw your own conclusions.

 

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madcarew replied to Anthony.C | 6 years ago
2 likes
Anthony.C wrote:
madcarew wrote:
Anthony.C wrote:

The point is the tools guarantee inaccuracy as they force the rollers apart and roller wear does not affect chain spacing and so shouldn't be included in the measurement.  Only pin/bushing wear affects chain spacing and performance. I use one myself but only consider replacing the chain when it drops in fairly easily on 1% if I can't be bothered measuring properly. 

But roller / bush wear does affect chain spacing. It is the only thing on your chain that wears. The links don't stretch. If the rollers are worn away inside (or outside) the distance between surfaces that the sprocket or chainwheel teeth catch on are further apart, and so cause wear on the teeth. Both methods, correctly applied will come up with pretty much the same answer. The vast majority of wear is on the inside of the rollers against the bushings and where the pins go through the links as that's where the grease / oil traps the grit and dirt and then the 2 surfaces grind against each other, whereas the interface with the teeth is largely static. 

The 'accuracy' that you talk about is trying to accurately measure an unknown / arbitrary number. We know that chains should be changed at about .75 - 1% wear (33% tolerance in measurement) to reduce drive train wear. This is just a guide number, and if either measuring method is within 10% (i.e. .825 - 1.1%) it still achieves the desired goal of picking a point of wear that is not too extreme but allows a reasonable life for the chain. 

This explains better than me why roller/bushing wear does not really affect spacing. http://pardo.net/bike/pic/fail-004/000.html 

That's a great technical argument, but is missing the point. It shows (the non effect of ) roller wear compared to a chain without worn bushings. In reality this isn't going to occur. The point is technically valid, but practically is almost without value. The common chain wear tools *seem* to take this in to account, as a 1% worn chain as measured with a standard tool *generally* shows 1% link extension as well. So, in theory Jobst is right (as usual) but in practice the standard tools provide an effective means of determining the chain wear. The point at which you chose to replace the chain is rather arbitrary. I'm a decent Cat 2 racer. I don't change my chains until they are beyond 1% wear. I go through a cluster about every 3-4 years (+/- 30,000 miles) and a chain every 3000 miles. The argument about wear on the rollers vs wear on the chain is rather academic, because as I said, it's chasing an accurate measurement of a poorly defined point.

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barbarus | 6 years ago
1 like

Replace preferably before it looks like this:

 

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mathcore | 6 years ago
2 likes

7800 km on my izumi super V and I ve just passed the 0.5% of stretch .  , the zen chainring still black on the teeths , she doesnt show any sign of wear .  JAPAN !

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996ducati | 6 years ago
0 likes

Having snapped a chain on a winter sportive I always carry the tool and links just in case now.Personally, for some reason my chains seem to wear diagonally (as opposed to streching) which the measuring tools dont always pick up so easily (cross chaining?) and at the rate of about two per year on 3000/4000 miles.

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Sub4 | 6 years ago
2 likes

Campag. I change chains shortly after .5%generally get 5  + chains before cassette rejects the new chain. Those cassettes are pricey! Record chains do last very well.

Shimano chains seems to wear v quickly & cheap ones seem to be at 0.5% from the box.

KMC is my chain of choice in the workshop.

As everyone has said, clean & lube regularly & they last a long time. Ignore them & watch them melt in a few weeks.

ps, if I had a quid for every time a customer said "that chain's nearly new, it can't be worn!" when the 1% goes through, I'd have lots of quids.

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Applecart | 6 years ago
0 likes

I really recommend Ultegra chains. I run 105 groupset and the generic (105?) chain my Cube came with snapped randomly. All the shop had was Ultegra and it felt immediately brilliant - silky smooth shifts and more solid power transfer. Not expensive, and I'm more likely to keep it clean for that good transfer + offset the cost.

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WolfieSmith | 6 years ago
3 likes

Always worth checking the jockey wheels too. Here's three years worth of wear with a chain change once a year on a summer bike. As you can see - the chain chews away pretty fast.Probably 6000 miles worth.

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Anthony.C | 6 years ago
1 like

I reckon a lot of people are replacing chains prematurely, those tools don't really measure chain 'stretch' they measure roller wear. The only reliable way to measure is with a good ruler. Having said that I just replaced a chain because it was dropping in easily on the 0.75 % side but I got a few thousand winter miles out of it.

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nbrus replied to Anthony.C | 6 years ago
1 like
Anthony.C wrote:

I reckon a lot of people are replacing chains prematurely, those tools don't really measure chain 'stretch' they measure roller wear. The only reliable way to measure is with a good ruler. Having said that I just replaced a chain because it was dropping in easily on the 0.75 % side but I got a few thousand winter miles out of it.

Yes, chains don't actually 'stretch' ... it is roller wear that is being measured and those chain neasuring tools work very well and are much simpler and more precise that trying to keep 12 links of a chain straight, in tension, lining up a ruler and trying to take a reading for stretch. However, I would not pay £9.99 for a chain wear tool ... I got mine from On-One for £2 some time back.

If you want your chain to last, then use a good wax dry lube.

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