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feature
When should you replace your chain? Photo by Chepe Nicoli on UnsplashDo you need a new chain? Find out the easy way to tell
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.”
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.
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.
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.
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.
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.
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. 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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74 comments
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.
But rolller wear is not what causes 'stretch' It is the accumulation of the wear of the individual chain bushings that cause the 'stretch' so measuring with a ruler is a less convenient but much more accurate way of determining when you need a new chain.
Both methods measure 'stretch' across several links, so pick whichever one is easiest for you. I wouldn't say one method was better than another, but using a ruler is more reliant on the operator taking a correct reading, whereas a chain guage requires no operator judgment at all ... its simple and repeatable pass/fail, though with the ruler you may be able to measure how much wear has taken place rather than the guage method which only shows when a wear limit is reached. Its the rollers on the chain that mate with the cogs in your gears and that is what a chain guage rests on to check for wear. As long as you have a method that you are happy using, then thats all that matters ... absolute precision isn't really required.
> This is Park Tool’s CC-3.2 chain checker (link is external) with an RRP of £9.99, although you’ll find it cheaper if you look around.
They are less than £1 from China. https://goo.gl/jxl7Z5 (no affiliation).
Chains I just change once a year, I do about 2000-3000 miles. I use KMC because their link is easy to take off/put on. I just fitted a new Shimano chain to my in-laws bike(he bought the chain), what a faff, those brittle little pins. You need a new one everytime, the chain has to come off.
Those who are concerned about wear, just use a steel rule to measure across 12 links in inches.
You can buy KMC links separately and use them to reconnect Shimano chains.
And clever little things they are too. My three bikes are all equipped with a 'Missing Link", it makes removing the chain a 20-second doddle.
This pre-emptive maintenance is a bit scary to me and my wallet. TBH I usually change my bike before I change the chain!
Admittedly, I've never done hyper miles, but I've never felt the need to check or replace a chain unless it was totally ruined (i.e snapped / siezed / super rattly / a really out of shape link). I would only even think of checking it if there was a problem with my shifting.
I've also never felt the need to replace a cassette or chainrings unless the teeth on them have done similar or it won't shift properly / makes terrible noise and all other solutions have failed (ie. adjusting mechs / new cables etc)...
For context, my commuter bike does Roughly 100 - 150 miles per week all weathers and I clean & lube the chain every 3-4 weeks if it's lucky when I sluice the bike down (fortnightly in the winter or if squeaking starts).
Most exotic drivetrain I've had is Tiagra..is that a factor? Do the more expensive parts wear more easily because they are lighter / thinner / different quality and therefore more delicate perhaps?
What am I missing out on by not changing this more frequently? I'm concerned that this sounds like a big important maintenance deal when I presumed a chain was...the most boring part of the machine and pretty indestructible!
Rotating chains sounds a good idea, but when I got my spare out of the draw amazingly it had started to rust, so storage needs to be well lubricated if the garage is at all damp. That's a bit messy for me, so am going the 'disposable item' route.
I degrease chain on removal and relube, then put into a Ziplock bag. A quick spray of whatever combo of 2 letters and 2 numbers you got laying about, seal up and stick in drawer - I write rough mileage on the bag too.
All that's left is give the chain a good wipe down and refit.
Most decent new chains are greased and sealed in a plastic bag, so can't rust; I prefer KMC chains because they are a dedicated chain manufacturer, unlike SRAM and Shimano, and are a lot tougher/longer-life than SRAM chains for daily MTB use.
There is nothing wrong with buying the lady in your life something shiny.
Honestly can't be arsed with all this chain rotation/replacement bullshit. I just ride my chain and cassette into the ground (until shifting becomes a real problem) then replace both at the same time. Last chain and cassette replaced three years ago both now with 18000 km on them and still shifting fine. I don't race, so couldn't care less if I miss a shift every now and again. Oh, and I'm not fooled by the marketing ploy of expensive chains - they wear just as fast as the cheap ones, you're just paying for the 'shiny stuff' and a miniscule weight difference - after a month in the filth of winter they all look, wear and shift the same.
ditto
...although I do have 5 bikes in rotation, so that's a 15 year replacement time frame for me
Ooh sir sir, me sir, I know this one.
You may and/or should replace your chain in any of the following circumstances.
A) The bloke in the bike shop rests his metal gadget on it, sucks his teeth and shakes his head
B) Bang on the wheel of your lead-out man, you round the final curve of the 1st-cat crit, put down all of your awesome power for the sprint ... and it snaps
C) You see a nice shiny new one favourably reviewed on road.cc
Can I haz the intern job now please?
Yeah, there's an optimal number of chains, which varies with use, so the chains, cassette and chainset all get to the end their lives around the same time. Sounds like a lot of faff to me... But if you like removing and fastidiously cleaning chains...
campag recommendation is the most reasonable IMHO
132.60mm measured for 6 links. see the picture attached.
http://i-vol.com/bikes/campagnolo_chain_info.jpg
shifting performance begins to deteriorate around this point though, so you'll notice it certainly, whitout measuring
campagnolo_chain_info.jpg
Rotate 2-4 chains every few hundred miles. The whole system will last longer and you'll never need to measure the chain wear.
Rotating chains has NO effect on longevity whatsoever, it is yet another one of those myths picked up on clubruns/forums which people pass on as if it were the absolute truth. Do you really think that taking a chain off and giving it a rest makes it last longer? Do you really believe that? Really?
It's Friday tea time , so I'm not in lateral thinking mode, but might rotating chains reduce wear on the chainrings and cassette?
I think if you take the chain off remember which way round it was and remember to turn it round the other way when refitting it after giving it a good soak, degrease and re lube then yes I'm sure that it may well help to increase longeviety
My personal view is fuck that shit - although I have had to replace a cassette to day so who's laughing now
The chains may not last much longer (if at all) but the whole drivetrain will. By rotating N number of chains you emulate the super chain with rate of wear / N.
You cassette and chainrings will be exposed initially to lower wear and all chains will be gradually "stretching" by the same amount so you avoid grinding the teeth of you cassette first with 0.75% worn and then with new chain (that's assuming that you remember to replace your chain on time...)
As I said before this system offers a simple answer to "when to replace the chain" problem.
So you are saying that by putting a new chain on a transmission that is already starting to wear (and will continue to wear when you use it with whatever chain you fit) you will increases the life of the transmission? Is that what you are saying? I don't think so, in fact you will expose your new chain to a worn transmission which will increase the wear rate of your new chain.
By the time your first chain reaches the end of useful lifespan - 0.75% stretch in a traditional method, three (e.g.) chains used in rotation will be worn approximately just 0.25% each, exposing other components to much less wear. That's the main difference.
I don't quite understand why some people here feel so worked up about it. Whether it's faff and it's worth it or not , it's up for individuals to determine.
It takes no time to disconect a KMC link and put another chain on. Many people do it anyway when they clean their drivetrains.
I have heard that if you remove and clean the chain, leaving a thin film of lubricant to coat it, then pop it in the microwave for 5 minutes, it will 'shrink' the wear on the chain....
Ive gone through a chain in well under 1000km. Stop start riding in London in the winter...and being 100kgs probably did for it...
One of the down sides of a recumbent. Chain swaps need three of the damn things...
Feels a little less disposable at £60+ a pop.
That's another reason my High Racer is a 'Sunday' bike. Must get it off the trainer now the clocks have moved.
If the chain is 3 times longer, it will last 3 times longer. Think about it - the average wear on each link is 3 times less as it is in contact with a sprocket under force 3 times less frequently over its lifetime. Therefore the price is the same.
The average wear on each is slightly less, but it is not contact with the sprockets that causes the wear, it is motion under pressure. The length of the chain has an influence, as the point of exit from the sprockets and entry to the chainwheel are the points of highest wear and it occurs less often in a long chain, but chain wear is not proportional to chain length.
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