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Do Chain Checkers really measure the stated %0.5, %0.75 etc. ?

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Do Chain Checkers really measure the stated %0.5, %0.75 etc. ?

Old 12-04-20, 12:31 AM
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John_E
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Do Chain Checkers really measure the stated %0.5, %0.75 etc. ?

This is my first post in the forums. Lately I was interested in doing a little experiment on how lubes/riding style affected chain wear on my bikes. I posted this question on ****** but soon realized that the user base for cycling was not the right one for such questions, not a single answer but some dismissive posts, oh well that is another story. Here is the original post.
I always relied on simple chain checkers like Park Tool cc 3.2 or Pedro's chain checker plus 2.

Lately I began using a digital caliper to measure chain wear to see the progression under different lubes, riding styles etc.

I measure 5 full links from outside, hence roller wear is not included in my measurements. Here are some results :
  1. Brand new Kmc 11speed chain around 5.007-5.011" so <= %0.22

  2. Waxed Kmce 11 speed chain , around ~650miles, almost identical to new, 5.006-5.011" hence <= %0.22

  3. Same Kmc chain on an emtb, around 850 miles, measures 5.012-5.019 hence <= %0.38

  4. Road bike chain, Sram, around 2k miles, measures 5.019-5.022 hence <=%0.44

  5. 10 speed Kmc mtb chain, around 1300 miles, measures 5.032-5.039 hence <=%0.78

Here is what Pedro's show (Park tool seem to agree although it measures the length with added roller wear):
  1. <%0.5, the checker tool show that 0.5 has not been reached.

  2. <%0.5 , same as 1

  3. There is one section where Pedro's show %0.5, it just fits in !!! the rest seems to be a bit smaller than %0.5

  4. =>%0.5 Pedro's 0.5 mark fit in comfortably in every section I measured !

  5. Both Pedro and Parktool fit comfortably and show >>%0.75 wear. !

Now I may be making a measurement error while using the caliper but I have tried many times and several different ways and my measurements seem consistent. I also tried to measure from inside but the knife edges of these calipers make it quite hard to take consistent measurements from the roller to roller since they may not stay parallel to the chain or knife edges may go in between side plates and rollers etc.


Also the problem is not the addition of roller wear as you can see I also use Pedro's chain checker which offsets that.


Although taking the whole chain out and hanging it side by side to a brand new one (same brand/model) would have been much better but I don't have the space for such a setup.




To explain this discrepancy between the checker tools and measurements I tried to measure the distance at the %0.5 wear mark in Pedro's. Measuring this distance is somewhat hard but it seems to be around 5.018 which is interesting since it should be 5.025.


It is still possible that I am making a mistake in my measurements.


So the question is:


-- Has anyone actually checked the accuracy of these tools ? Especially measuring these tools' length as accurately as possible? I want to know If these tools really measure %0.5 wear or something smaller like %0.35-0.4?

I will appreciate if the discussion stays focused on this particular question.

Thanks in advance.
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Old 12-04-20, 12:44 AM
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As a basic test, measure a brand new chain. Many checkers will falsely show "some" wear right off the bat.
On a used chain, I'll measure a 3' section with my tape measure to get better resolution and then use that to check the checker.

Simply stated, many checkers show wear that hasn't occurred, so you have to determine how far off the checker is. IOW, calibrate-

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Old 12-04-20, 02:15 AM
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I prefer to measure it on the bike, under the tension of the rear DER. I use a stainless steel ruler, 1' long, and measure from center of rivet for 12 full links. I find this to be the most accurate
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Old 12-04-20, 04:17 AM
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Thank you for the replies. I completely agree that with a standard ruler the measurement should be done on a long section under tension.

I am doing the measurement while the chain is on the bike under tension and I hope to get a similar precision with a digital caliper on 5". The digital caliper I use seem to be accurate enough to give me the stretch at 5" (it has 0.0005" accuracy) as long as I measure it right.

So you guys also agree that these drop in chain checker tools are actually shorter than they should be. Have you ever measured one with a digital caliper?

What was the largest difference you have observed? (That is, when the tool drops in %0.5 what was the shortest real stretch you have measured?).

In my measurements chain checker seems to hit %0.5 when my measured wear is as small as %0.36-%0.38.
Also some chain checkers claim that new chain usually shows at least %25 but in my measurements it measured as little as %0.1.
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Old 12-04-20, 05:36 AM
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This is from another thread but the poster says he is with KMC. He has very informative posts about chains.

Originally Posted by Papa Ado View Post
The easiest and most convenient way to check chain elongation is at the rollers which also includes other chain wear at the inner link sleeves and pins. It's not perfect but most users won't measure actual chain length so that is why we suggest 0.8% and offer "easy chain checkers" and "digital chain checkers" for most users.
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Old 12-04-20, 08:46 AM
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If all you want to do is check elongation or change in pitch, it's most easily done with a cleaned chain laid out on a bench. At one end I have a close fitting pin made from a 10D nail protruding from the bench and at the other I have a 6 inch precision machinist's rule taped to the bench, with the center located precisely at 54 inches. Most chains use a quick link, one end is placed over the pin and the center line of the hole at the other end will be 52.5 for a 53 inch chain, 53.5 for a 54 inch chain and so on. 0.5% is just over .25 inch, making it easy to measure elongation with the precision rule.

No chain will be perfect. I've measured new chains that are a little long and others a little short when new.

The bigger problem is some chains don't show much elongation even after 6000 miles of use, when the rollers have lots of wear and the side clearance is twice that of a new chain. If that chain was used exclusively on one cassette, you may encounter new-chain skip on the most worn sprockets, when a new chain is installed. I avoid that problem by using several chains in a rotation. Chains can be used longer and new-chain skip will never occur.

Most caliper tips won't fit between the inner plates, so measuring between them will be inaccurate. I've made a plug gage from a 6mm hex wrench, ground down thin enough to fit between the outer plates. If that gage ever slips through, the rollers are excessively worn.

FWIW, Campy recommends measuring between the rollers of the outer plates and tossing a chain if the length exceeds 132.6mm. I think that sells more chains, since most of what you're measuring is roller wear, not elongation.

Last edited by DaveSSS; 12-04-20 at 12:03 PM.
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Old 12-04-20, 08:53 AM
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To the man with a hammer, everything looks like a nail.

You could probably rig up some way to measure a single link with a digital something or other, but using 12 links or12" magnifies the wear by 12 (or more than twice as much as five links / inches), and makes it much easier to see wear. Other than using your new digital caliper, I'm not sure why you prefer that to a tape measure or ruler.

I admit that I use the Park tool as a first check -- it saves my knees and neck. If I see wear above the 0.5% indicator, then I get down load and look through my bifocals at the chain and ruler or tape measure to verify. More than 12-1/16"? Time for a new chain!
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Old 12-04-20, 09:12 AM
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Originally Posted by John_E View Post
....I am doing the measurement while the chain is on the bike under tension and I hope to get a similar precision with a digital caliper on 5". The digital caliper I use seem to be accurate enough to give me the stretch at 5" (it has 0.0005" accuracy) as long as I measure it right.

So you guys also agree that these drop in chain checker tools are actually shorter than they should be. Have you ever measured one with a digital caliper?
At what temperature? Just because it's a digital caliper doesn't mean you have an accurate reading, considering the inherent inaccuracy of a digital display and thermal expansion of a steel chain re: temperature.

My checker reads ."about" .25% worse than reality on the "short" side with a "snug" fit. I haven't had a worn enough chain to check the "long" side.
So, as long as the short side says "good" to "snug", I know I don't need to check further.
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Old 12-04-20, 09:24 AM
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This reminds me of the phrase "measuring with a micrometer and cutting with an axe".

Given the widely varying opinions on how much wear is too much why does one need "accurate" measurement?
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Old 12-04-20, 10:07 AM
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So the question is:


-- Has anyone actually checked the accuracy of these tools ? Especially measuring these tools' length as accurately as possible? I want to know If these tools really measure %0.5 wear or something smaller like %0.35-0.4?
I've never cared to check them for accuracy.

I use a chain checker for a quick measure so I don't have to be in good lighting and at the angle of eyesight to see everything with the chain still on my bike. When the quick check shows or begins to show, then I'll use something else.

IMO a metal scale measuring out how twelve links compares to 12 inches is accurate enough. Chain wear on a bike is not rocket science. But if that makes it more fun to you, then go for it. But you'll have to put up with my rolling eyes!
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Old 12-04-20, 10:11 AM
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I keep it really simple. Tape measure while on the bike. 1/16" or greater - it comes off and bagged and marked at its elongation, When new chains stop working it is time to decide whether to use those older chains and run all my cogs and rings into the ground or swap out the cassette and chain and prolong the life of the chainrings. (At 14,000 miles for this bike with its three cassettes and two wheels, new chains are still running just fine. )

Take the chain off and clean it just to measure it? I know any worthy bike owner regularly takes his chain off and cleans it. I don't. Lube and wipe. Ride. Seems to work. (See above.)
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Old 12-04-20, 10:16 AM
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In my experience, those chain checkers are not great. I have tried them on new-in-box chains and seen .5% wear. THat was some years ago so maybe they make them better now. Still seems to me like an expensive and potentially inaccurate way to do something that can be easily and more reliably done with a 12" ruler.
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Old 12-04-20, 10:17 AM
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I have a reasonably good caliper, certified at 0.02mm accuracy.

The problem wrt measuring a bike chain is that the way you position your caliper will have a definite impact on the reading. I took 30+ readings over a couple of weeks, on a slightly used but clean chain. The measurement MAPE (mean average percent error) turned out to be 0.28%. (compare it to the critical value of 0.5% at which a chain might/should be retired and you may conclude that it is too high or somewhat ok). My personal conclusion is that using a caliper isn't particularly useful.

I find it much easier to nail a new chain to the wall use it as a reference for the chains I use in rotation -- I hang the used chain on top of the reference (i.e. hung to the same nail) and retire it it gets close to one link longer. A chain is much cheaper than an accurate caliper, more accurate (probably < 0.05%), and is fast and foolproof.
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Old 12-04-20, 10:23 AM
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Originally Posted by gauvins View Post
I have a reasonably good caliper, certified at 0.02mm accuracy.

The problem wrt measuring a bike chain is that the way you position your caliper will have a definite impact on the reading. I took 30+ readings over a couple of weeks, on a slightly used but clean chain. The measurement MAPE (mean average percent error) turned out to be 0.28%. (compare it to the critical value of 0.5% at which a chain might/should be retired and you may conclude that it is too high or somewhat ok). My personal conclusion is that using a caliper isn't particularly useful.

I find it much easier to nail a new chain to the wall use it as a reference for the chains I use in rotation -- I hang the used chain on top of the reference (i.e. hung to the same nail) and retire it it gets close to one link longer. A chain is much cheaper than an accurate caliper, more accurate (probably < 0.05%), and is fast and foolproof.
By one link, do you mean half a link (one side plate)? Half a link over an 110 link chain would be about 0.5%, so that would be a good measurement. Do you use that chain and hang up a new one?
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Old 12-04-20, 10:30 AM
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yes, seen this way, half link (never clear to me, some talk about inner/outer).

And so far, the reference chain has not been rotated. I consider it as a decor accessory
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Old 12-04-20, 11:55 AM
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Originally Posted by pdlamb View Post
To the man with a hammer, everything looks like a nail.

You could probably rig up some way to measure a single link with a digital something or other, but using 12 links or12" magnifies the wear by 12 (or more than twice as much as five links / inches), and makes it much easier to see wear. Other than using your new digital caliper, I'm not sure why you prefer that to a tape measure or ruler.
Agreed. Digital calipers give the illusion of precision. In reality you cannot line up the calipers perfectly square or orthogonal to whatever you are trying to measure. Try to measure the seat tube hole for example- you'll get totally wrong numbers. So all that precision is misleading.
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Old 12-04-20, 12:04 PM
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Originally Posted by Bill Kapaun View Post
At what temperature? Just because it's a digital caliper doesn't mean you have an accurate reading, considering the inherent inaccuracy of a digital display and thermal expansion of a steel chain re: temperature.

My checker reads ."about" .25% worse than reality on the "short" side with a "snug" fit. I haven't had a worn enough chain to check the "long" side.
So, as long as the short side says "good" to "snug", I know I don't need to check further.
Good point, I measured before and after rides, under different temperatures. That's why I gave the worse case range in my original post. If the chain is cold I measured as little as 5.001 ~ %0.02.
%0.25 is a lot but I am also experiencing something in the range of %0.15 so I wouldn't be surprised.

Originally Posted by gauvins View Post
I have a reasonably good caliper, certified at 0.02mm accuracy.

The problem wrt measuring a bike chain is that the way you position your caliper will have a definite impact on the reading. I took 30+ readings over a couple of weeks, on a slightly used but clean chain. The measurement MAPE (mean average percent error) turned out to be 0.28%. (compare it to the critical value of 0.5% at which a chain might/should be retired and you may conclude that it is too high or somewhat ok). My personal conclusion is that using a caliper isn't particularly useful.

I find it much easier to nail a new chain to the wall use it as a reference for the chains I use in rotation -- I hang the used chain on top of the reference (i.e. hung to the same nail) and retire it it gets close to one link longer. A chain is much cheaper than an accurate caliper, more accurate (probably < 0.05%), and is fast and foolproof.
I completely agree that positioning plays a big role in taking measurements that's why I am also trying to see if the discrepancy was due to my inability to measure it right.
That is also the reason why I am not trying to measure roller to roller distance from inside the chain since those knife edges make it almost impossible to get a consistent reading (they don't fit well and make it hard to alight the caliper with the chain line ). However from outside the chain, just like using a ruler, I believe I get fairly consistent measurements. I try to get at least 5 measurements from different sections.

Since these chain checkers are also measuring a similar, around 5"/5 full links, distance I think it is fair to compare the digital caliper readings with a chain checker. I believed these drop in chain checkers were machined precisely (otherwise it is just a piece of metal) so it should be by design that they measure less than what they should. Have you tried to measure the chain checker itself with your caliper?


As you have mentioned, hanging the chains side by side is the better way of measuring average chain wear (unfortunately I don't have the space for it atm). One problem with this approach is that there will be variance section by section and while the average may be well within %0.5 there may be individual sections that exceed it. With chain checkers we take the worst section(say 5 full link) wear rather than the average.
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Old 12-04-20, 12:14 PM
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Different field, but in my work I find calipers are about the only measurement tool I can actually trust. The starting point on most tapes and rules is iffy enough, but when you get to single-purpose tools similar to chain checkers they can be all over the map. I once paid $80 for a very simple tool (two moving parts and a spring) and it was designed wrong so that it was doomed to be exactly 20% off. . . and had been for the entire 30 years it had been on the market, so I scraped off the scale and calibrated it myself. If you really want a 100% accurate chain wear gauge [Does it really matter? I have no idea], sit down with a file and make one. :-)
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Old 12-04-20, 12:32 PM
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Pedro's makes a chain checker that is accurate and not too expensive. shimano makes one also but it about 60 bucks.
Chain Checker Plus II » Pedro's NA
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Old 12-04-20, 01:52 PM
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Originally Posted by John_E View Post
Good point, I measured before and after rides, under different temperatures. That's why I gave the worse case range in my original post. If the chain is cold I measured as little as 5.001
You are not measuring your chain with a precision of 1/1000 of an inch, I don't care what your digital caliper says. That's about the thickness of an eyelash.
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Old 12-04-20, 01:54 PM
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John_E
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Originally Posted by mdarnton View Post
Different field, but in my work I find calipers are about the only measurement tool I can actually trust. The starting point on most tapes and rules is iffy enough, but when you get to single-purpose tools similar to chain checkers they can be all over the map. I once paid $80 for a very simple tool (two moving parts and a spring) and it was designed wrong so that it was doomed to be exactly 20% off. . . and had been for the entire 30 years it had been on the market, so I scraped off the scale and calibrated it myself. If you really want a 100% accurate chain wear gauge [Does it really matter? I have no idea], sit down with a file and make one. :-)
I also find digital calipers more accurate than rulers. I am not after a %100 accurate gauge. My question is whether these drop in checkers really measure what they say they do. My suspicion is by design they actually measure significantly less than the advertised %0.5 wear. Did you have any chance to measure one of these checkers ?

Originally Posted by davidad View Post
Pedro's makes a chain checker that is accurate and not too expensive. shimano makes one also but it about 60 bucks.
If you read my post you will see that I am using that exact checker. I measured it to be around %0.35-0.38 instead of %0.5 which is a significant difference, especially if the tool is really laser cut.
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Old 12-04-20, 03:08 PM
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Originally Posted by John_E View Post
Have you tried to measure the chain checker itself with your caliper?
I hadn't, but just did. My caliper reads 5.02545" on a Shimano chain checker, i.e. a little longer than .05% elongation. Now, my understanding is that the checker's end should "fall' between rollers -- not being pressured, which I assume adds a tiny bit of length to the measurement. Bottom line, the checker seems accurate, if a little bit forgiving.

[Edit] actually, not sure at all. I've assumed that I could take the "outside" measurement, without any supporting evidence. Positioning the caliper correctly is difficult/impossible because part of the checker pushes rollers -- so the measurement will depend on how hard you push.

Last edited by gauvins; 12-04-20 at 03:22 PM.
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Old 12-04-20, 04:17 PM
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Originally Posted by John_E View Post
If you read my post you will see that I am using that exact checker. I measured it to be around %0.35-0.38 instead of %0.5 which is a significant difference, especially if the tool is really laser cut.
What checker did you use to check your checker checker?
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Old 12-04-20, 04:52 PM
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Originally Posted by gauvins View Post
I hadn't, but just did. My caliper reads 5.02545" on a Shimano chain checker, i.e. a little longer than .05% elongation. Now, my understanding is that the checker's end should "fall' between rollers -- not being pressured, which I assume adds a tiny bit of length to the measurement. Bottom line, the checker seems accurate, if a little bit forgiving.

[Edit] actually, not sure at all. I've assumed that I could take the "outside" measurement, without any supporting evidence. Positioning the caliper correctly is difficult/impossible because part of the checker pushes rollers -- so the measurement will depend on how hard you push.
Thank you for trying, ah Shimano's checker is even harder to measure since it is almost impossible to guess where the roller sits on the middle section. Even with Pedro's, which works the same way, it was hard but at least I can take the middle of the curved middle section as the spot where roller supposed to sit.

I think the easiest to measure would be Parktool's CC 3-2 but I lost that thing and don't want to buy another one just to measure the distance. Maybe someone who has Parktool's checker can do that.
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Old 12-04-20, 05:08 PM
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I ended up getting the Park CC 4 chain checker because I had a discount at Nashbar and ended up getting it for like $7.00. I find it accurate enough for me. I had been measuring with a 12” steel ruler, which is just fine. But, as mentioned in one of the posts above...for real accuracy the chain needs to have some tension. And I suppose the rear derailleur puts enough tension on the chain to measure the bottom of the chain (coming off the chain wheel and going to the rear). But I always felt kinda like I wasn’t holding the ruler precisely in the right spot. The Park CC 4 checker has a little area that, after you hook it into the link, you pinch the chain to the tool to provide the tension required. The end where the reading is taken has two notches on it. If the prong doesn’t fall into the link at all, the chain is 0-49% worn. If it falls to the first notch it’s 50-74% worn. If it falls completely through the link it is worn 75% or greater.

Dan
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