Technical Tuesday: Chain Wear

Jun 8, 2010 at 0:08
Jun 8, 2010
by Mike Levy  
 
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For today's Technical Tuesday we're going to have a closer look at chain wear. We'll explain what exactly is happening to your drivetrain as it wears, as well as how to properly check your chain to see if it's time to replace it. Inside you'll find a video full of information and step by step instructions on how to find out just how worn out your poor chain actually is!

Read on...

One thing that all of our bikes have in common despite their intended discipline, amount of travel, or wheel size, is that they're all powered by a bicycle chain. And from what I've seen, there is a pretty good chance that your chain is either already worn out or is very close to being so. Reading comments from past Technical Tuesdays it is pretty clear that everyone wants to learn how to rebuild their suspension or lace up a wheel, and we will be covering those jobs down the road, but we still have some relatively basic tasks to cover first. It's incredible how many very expensive bikes I've seen that have the latest and greatest parts on them, but have drivetrains that are completely worn out. This is unacceptable in my books! For this Technical Tuesday we are going to show you how to not only properly check for chain wear and some of it's symptoms, but we'll also explain exactly what is happening to your drivetrain as it becomes more and more worn. Watch the video below and then have a look at a past Technical Tuesday that shows you how to properly use a chain tool and replace that poor worn out chain of yours!


Watch the video to learn about chain wear and how to check for it:

Views: 31,981    Faves: 49    Comments: 10




Step by step instructions on checking for chain wear

Tools needed: Chain checker or tape measure.


A Park CC-2 chain checker or a tape measure can be used
A Park CC-2 chain checker or a tape measure can be used

A modern bicycle chain is made up of inner plates, outer plates, pins, and finally the rollers. The pins are pressed through the outer plates and the rollers and inner plates are free to rotate on them. This allows the chain to circle freely around the chainrings, cogs, and pulley wheels. Two things are happening to your chain as it begins to wear. The most obvious symptom is known as "chain stretch", but the name is a bit misleading. It would be easy to be mistaken in thinking that the inner and outer plates actually stretch with use, but that isn't the case. What is actually happening is the tolerances of the press fit between the chain pins and outer plates is increasing over time and as the small gaps get bigger, the distance between the chain pins get bigger and the total length of the chain increases. The other symptom of a worn chain is rollers that both seem to have shrunk in size, as well as have a lot more room to "float" in the space between the two inner plates. As a chain is used, the rollers slowly get worn down from contact with the cogs and chainrings. As they get smaller, the gap between them obviously increases in size. Further exasperating this issue is how the roller has room to rattle or float within the inner plates. This is caused by wearing down of the inner shoulder that the rollers turn on. So the question is then, how does a worn chain effect the rest of your drivetrain?


A chain is made up of the inner plates, outer plates, rollers, and chain pins
A chain is made up of the inner plates, outer plates, rollers, and chain pins

One complete link consist of a both inner and out plates
One complete link consist of a both inner and out plates

A new bicycle chain has a pitch of 1/2" (pitch is the measurement from one chain pin to the next) that matches the same pitch on our chainrings and cogs. The pitch of a chain gets longer as a chain wears. The chain rollers that apply torque to the same spot on each gear tooth as you pedal will slowly wear the teeth as well, although at a slower rate than the chain itself wears. The teeth on the cog or chainring are shaped to work perfectly with the size of the rollers on a half inch chain, as well as being just the right distance apart from their neighbor. Material is slowly removed from the leading edge of the gear teeth as a worn chain applies torque to them, and the ever important distance between each tooth actually gets larger as this happens. This is most evident when you install a new chain on a worn out cassette and discover that it skips under load. Simply put, the new chain will not fit the worn cassette due to the gaps between the teeth now being too large for the new chain and it's 1/2" pitch. There isn't enough engagement to keep it from skipping as you pedal hard. Because a chain wears faster than a cassette, it makes sense to replace your chain multiple times before they become too worn, thereby making your cassette last much longer. The teeth on a worn cassette will have a much more pronounced point to them and look very much like a shark's fin. Chainrings generally wear much slower due to much more contact with the chain which distributes the load over a greater area. Even when a large chainring is badly worn, it may not skip simply due to the amount of wrap that the chain has around it. Middle and small chainrings are another story though...

Measuring a chain with Park's CC-2 chain checker

Step 1. Turn the gauge on the CC-2 tool to zero and place both pins into the gap between the rollers
Step 1. Turn the gauge on the CC-2 tool to zero and place both pins into the gap between the rollers

Step 2. The gauge on the CC-2 tool tells you just how worn the chain is. Replace if it's at .75 or higher
Step 2. The gauge on the CC-2 tool tells you just how worn the chain is. Replace if it's at .75 or higher



Measuring a chain with a tape measure

Step 1. Using a tape measure, line up the 0
Step 1. Using a tape measure, line up the 0" mark directly with a chain pin

Step 2. Six complete links on a chain in good shape will measure in at 12
Step 2. Six complete links on a chain in good shape will measure in at 12". Any more that 1/16" needs replacing





Don't fret if you don't have a specific chain measuring tool, you can also use a standard tape measure or ruler to figure it out. Just like using a chain checker, you can do this while the chain is still on the bike.

• Line up the tape measure so that the zero inch mark is directly in line with one of the chain pins.

• Holding the tape measure in line with the chain, measure out exactly 6 complete links (A link is a set of both inner and outer plates).

• Because the pitch (distance between each link) of the chain is 1/2", 6 complete links on a new chain will measure exactly out to 12".

• If the chain has wear, the pin will line up slightly past the 12" mark on the tape measure. A general rule of thumb is to replace the
chain once it is over 1/16" past the 12" mark.




Past Tech Tuesdays:

Technical Tuesday #1 - How to change a tube.
Technical Tuesday #2 - How to set up your SRAM rear derailleur
Technical Tuesday #3 - How to remove and install pedals
Technical Tuesday #4 - How To Bleed Your Avid Elixir Brakes
Technical Tuesday #5 - How To Check And Adjust Your Headset
Technical Tuesday #6 - How To Fix A Broken Chain
Technical Tuesday #7 - Tubeless Conversion

Have you found this tutorial helpful? Share any of your hints or tips below!

Visit Parktool.com to see their entire lineup of tools.
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72 Comments

  • + 30
 Thanks Mike for another informative Tech Tuesday.
  • + 22
 Measure from 1" it's way more accurate than using the end of that over used tape measure
  • + 12
 good articles, keep em coming!
  • + 12
 i love tech tusdays. yea i look forward to tusdays
  • + 12
 agreed!
  • + 3
 i'll hit the brakes he'll fly right by us.
  • + 12
 Great information and much appreciated! Cheers!
  • + 4
 Nice article!

Another rough-and-ready way to check chain wear is to put the chain on the biggest chain ring and see if you can pull the middle of it away from the ring - takes some time to figure out how far means worn out, but it's quick.

Also, you should check out the late venerable Sheldon Brown's article on this: sheldonbrown.com/chains.html . He was the man.
  • + 4
 The best way to ensure your chain wears more slowly is to keep it clean and lubed.

I add not to use degreaser ever on your chain - just run it through a rag, brush it, and lube it - that's how I get the best mileage - sorry skippy888, I mean kilometerage Wink )
  • + 1
 why not use degreaser?
Do you mean not even the Park Tool stuff? I use that on a regular basis with Cyclone chain cleaning tool. And now I have Pedro's creamy lookin stuff that you put right on and scrub which seems to work real nice.
  • + 3
 A guy at Rohloff (who make arguably the best chain) told me that degreaser removes the grease from the parts of the chain that lube will never get into. I used to clean the hell out of my chains and I got MUCH shorter chain life and couldn't understand why.

If I clean a chain after every ride in degreaser until it is shiny I will get 1000miles out of it. If I never touch a chain with degreaser and only run it through a rag and lube it I will get 6-8 thousand miles out of it. Obvioulsy this is the opposite of the expected outcome.

Shimano also worked out that if you flip your chain over regularly you will also get another 15% life out of it - but they never worked out why. I saw that in a magazine a million years ago and have never heard or seen it again - probably because Shimanos chain sales went down 15%!
  • + 1
 Thanks!
  • + 0
 I only use the degreaser and chain cleaning device after muddy rides or once a month in the dry season. Then I make sure to let the chain dry and lube it. Then before the ride lube it again and clean the excess. iamamodel is right, using degreaser will take out lubricant off the most inner parts of the chain, but it will also clean it. If you make sure to lube it right, then it shouldn't be a problem. Lubing it right means using a wet lube (not teflon or the "dry" lubes) and applying it 2 or 3 times, cycling the chain in between and maybe let it seat for a while to give the lube time to get in.
  • + 6
 love the Technical Tuesday i did learn something and alot of good comment for reference
  • + 7
 Chains make me go fast! go chains!
  • + 3
 i agree... go chains
  • + 7
 they should mention cassette wear too cause it usually goes hand in hand
  • + 2
 Use it til it's scrap, then change both chain and cassette. Changing chains increases the rate of cassette wear and costs you more money a) 'cos you're buying more chains and b) 'cos you cassette doesn't last as long.

It's not rocket science! Smile
  • + 1
 yes but you are also wearing your chain rings and they are very expensive to replace. You can run a cheap $20 Shimano HG53 chain if $$ are the issue.
  • + 2
 Here's the thing: for road and cross country bike, chain and cassette wear occur at the sam time. For downhill bikes, you're chain is being absolutely destroyed by suspension movement and bumps, even when you're not pedaling. So chain wear occurs much sooner than cassette wear on a downhill bike. In fact, cassettes typically last super long on downhill bikes, because comparatively, we do very little pedaling. So keep replacing that chain 2 times a season or so, and your cassette can last for 2 or more years.
  • + 1
 if you run 1/8 and dont want a half link look at this www.chainreactioncycles.com/Models.aspx?ModelID=38320 great qaulity chain and has better reviews than the more well known branded expensive ones and also a cheap ass price Smile
  • + 1
 nice article guys
but have to complain about one sentence: "...chain stretch. this isnt actually descripting what is happening...."
iam sorry but it IS chain stretch. that is what is happening with the chain! INCLUDING the pin-gaps get stretched too.
this and every other metal, will be stretched when its strained. also if the strain is far below the yield strengh. after 100... or more cyclic deformation you will be able to measure a elongation also from the plates.
  • + 1
 Actually the "stretch" is just wear. Like on a track type tractor as links and sprockets wear the spacing for the chain gets exaggerated when the sprocket wears. The chain wears out getting longer and the sprocket wears out getting a smaller circumference making the chain stretch seem worse than it actually is.I dont know how strong you are but last i checked i wasnt able to stretch steel past its elasticity point. Oh and fatigue is a whole other thing.
  • + 2
 it seems that you didtn understand what i was trying to say... but anyways iam not talking about stretching steel past its elasticity point. iam talking about stretching it way under its elasticity point. thats what you do with your chain day in day out. the material is not realy 100% elastic. if it would be, a chain would never wear. so everything and also the chain links get longer with the time. this stuff is my daily business as graduated engineer. i know what iam talking about.
  • + 1
 I have to agree with loveless75, it is not stretched, it is worn on both the pin and the chain resulting in a stacking of tolerances and giving the appearance of stretching.
  • + 1
 Hum ... Park Tool marking great tool but that CC-2 Chain checker is crap. I tested it on a brand new out of the box chain and it was showing 50% wearing. Personally I use Shimano or a mesuring tape. Those are way more accurate!
  • + 11
 Even a new chain will register some slack with most tools. There has to be enough for the chain to pivot at each joint, as well as differences in manufacturing tolerances.
  • + 1
 Aren't you supposed to measure chain wear by putting the non-movable pin of the tool between the outer plates of the chain, and the movable pin between the inner plates of the chain?
  • + 1
 but does changing the chain require changing both the cassete and the ring? cause they re both getting worn down as well sa the chain and the gaps between teeth are also getting bigger. it seems quite logical that the new chain want work with used cassete and ring as well as the old one or am i just wrong??
  • + 11
 It depends on how worn out the drivetrain is. I go through 4-6 chains before I find that I need to replace my cassette and probably two 32 tooth chainrings as well over that time. If you replace your chain at the 75% point, you will save money in the long run as the rest of your drivetrain will last much longer.
  • + 1
 I think a further attention to the meshing of a new chain and old cassette is necessary in this article. It's not noted on the video much at all, by not doing so someone is guaranteed to measure their as way off the guage. Replace it and then have a non meshing drivetrain. Which is potentially dangerous under the wrong person.

This is the worst problem for weight weenies. £60 chains and £120+ cassettes. For something that needs frequent replacement. At least I made the decision to stop pedalling up hills, saves my drivetrain and wallet that much more! Smile
  • + 1
 yea I'm with you, that's what trucks and chair lifts are for.
  • + 1
 >> "Six complete links on a chain in good shape will measure in at 12". Any more that 1/16" needs replacing"

Thanks for this info. Though sorta basic, I always forget the exact numbers.
  • + 0
 this helps but i normally just replace both
@NorCalNomad cheers for that Wink i saw how worn his tape measure is! no wonder it measures over!

@infamous, i get 1/2'' for each link makes 24'' for 12 links :s
its actually the text below the picture is wrong,
its 6'' for 12 links (so from above go from 1'' to 7'', this way you wont have an error (minimises the chances of it being wrong even if your tape measure is good from 0, like mine.))
  • + 5
 A "complete" link is one set of inner AND outer plates (i.e. every 2 pins). Therefore, there are 12 complete links per 12 inches (not 24, not 6).
  • + 1
 His tape measure isn't worn, the play in the little hook at the end of a tape measure is there on purpose to compensate for the thickness of that hook so it will measure accurately whether it is hooked on the edge of something or pressed against it. I replace my drive trains at the begining of every season, especially on the 4X bike, snapping chains out of the gate hurts...a lot.
  • + 23
 Smike is right...........why is there so much confusion on this?
  • + 3
 I have never replaced a chain on any bike I have owned, is this bad?
  • + 1
 if it aint broke...
  • - 1
 i change when it breaks. chains are too damn expensive. also, id like to go back to good old 8 speed with stronger chain but its sad that they no longer make high quality 8 speed cassettes and shifters. moving to 9 speed is one of that worse thing happening to bike industry for a guy like me.
  • + 1
 @smike - thanks for clearing that up, it is the pitch that is 1/2'' which is pin to pin, not a link, its not very clearly stated above
  • + 1
 before when i started biking id juste wait for the chain to snap but not anymore now i check my chain every 2 to 3 months somethime sooner
  • + 1
 does this work the same for bmx half link chains? or what? cause as far as i know bmx chains have shorter links than mtb chains.
  • + 1
 I got in a huge argument over "stretch" and now I have more evidence on why I was correct. Thanks Mike.
  • + 1
 this tip is very good, i measured it and it is in a very good condition, however i always clean it and lube it.
  • + 0
 Always good, but why not talk other peoples languages a lil bit? Aka imperial isnt everything.
No probs for me as I know what he's talking about. No beef seriously.
  • + 4
 In this case they must talk Imperial because our chains are based on Imperial.

How about 10 links = 254mm, replace at 256 (which is 0.79% wear).
  • + 1
 anyone know what bike that was? it looks sick as hell!
  • + 1
 lapierre DH-720
  • + 1
 awesome, thanks!
  • + 2
 thanx for this!
  • + 4
 i checked mine about a month ago and it was off the scale haha, its to expensive to replace your chain nearly every month
  • + 5
 but much cheaper in the long run!
  • + 5
 This is all very good to know, but I think the reality is that none of us can afford to change chains as often as that gauge would like. I usually go one full season on a chain, two seasons or so on a cassete. I have no need to gauge because my bike is always shifting crisp. The chains are def worn out by the end of a hard season, I just cant justify changing it more often. Same with cassetes, you almost HAVE to push the envelope. But again, this is usefull, everyone should be aware of whats going on with their drive-trains so that they can identify issues.
  • + 4
 how can it be cheaper in the long run??????????
Your having to spend loads on new chains
  • + 6
 Its cheaper in the long run, because a worn chain will wear out a cassete, chainrings and even your rear deraileur alot faster than if you have a good chain...
  • + 2
 it's cheaper in the long run because occasional replacement of the chain is considerably cheaper than replacing the chain, chain rings, jockey wheels and cassette. it just makes the drivetrain last that little bit longer. Besides, a new chain is hardly bank breaking.
  • + 4
 thanks McLovin!
  • + 4
 Consider the cost of a 'decent chain for a 9 speed cassete such as the SRAM 991 being £15 and they slacken within quick a short space of time for example a month that can get expensive !
Thank god for single speed.
  • + 1
 yessssss my man!!
  • + 1
 I guess the next question that really needs to be answered is:

How can you tell when your cassette/chainrings/jockey wheels have worn enough that they need to be replaced? It has to do with the teeth getting rounded, but a clear presentation of exactly what to look for would be nice.
  • + 1
 if you can see wear on your cogs with your eyes, its about time for some new ones!
  • + 1
 yeah just common sense. if your teeth are rounded or your missing chunks out of it chances are you might want to get a new one.
  • + 1
 Fair enough, it does say so in the article.
  • + 1
 Theres also a tool to check to see if your cassete and chainrings are worn...
  • + 1
 12 complete links measure to 12", not 6 complete links.
  • + 1
 a complete link contains both outer and inner plates, so by your working 2 links is one complete link
  • + 1
 infamous is right. have a look at www.kronowit.com/bicycling/chainstretch.html
  • - 1
 One thing it doesn't clarify is how hard to press the gauge on the chain checker, and which part of the chain, inner or outer set of plates, to put it on.
  • + 2
 The pins and rollers are all the same distance apart so it doesn't matter where on the chain you put it. I don't press it at all, if it doesn't fall in then I'm happy (that's with the simpler park tool).

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