# Chain wear indicator tools. Which one?



## e39540is

I am wanting to get a chain wear indicator, and am not sure which one to get. What makes the Shimano one so expensive, and the park one so cheap? Does the park one do the job?


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## frdfandc

This is your best wear indicator tool.


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## Kuma601

+1 for a machinist ruler.
A 6" version should be about $6


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## DaveT

The typical chain wear indicator, such as the one from Park, only measures the distance of the rollers from each other. The 'official' indication of chain wear is from pin to pin which measures chain elongation, not roller to roller.That's why you should use a metal ruler.


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## Waves77

Anybody have any experience with the new Feedback one?


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## DaveT

Waves77 said:


> Anybody have any experience with the new Feedback one?


The Feedback Sports tool still checks only the distance between the rollers, which is not a good gauge of chain wear. It's a go/no go gauge. The most accurate method to measure chain elongation is metal 12 inch ruler and measure from pin to pin to check chain elongation. The go/no-go tools have all the flaws of those that display wear values. _When the tool says the chain is worn out, it's not measuring elongation, it measure a lot of roller wear and false wear due to roller spacing differences. It will read a new chain to be half way Worn out and worn out when it's about half way there._

Measure it yourself, 12 links, pin to pin. 1/16 of an inch-replace.


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## PlatyPius

Waves77 said:


> Anybody have any experience with the new Feedback one?


Haven't even seen that one yet. I'll have to check it out.

Otherwise, I like the Wipperman one. (or a ruler. Hard to show a customer WHY it's bad with a ruler, though.)


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## TomH

I have maybe 10-15 thousand in tools (not bike specific, but still), and id be damned before Id buy a chain measuring tool. 

Its like buying a special 30 dollar cereal eating utensil when you've got a drawer full of spoons.


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## PlatyPius

TomH said:


> I have maybe 10-15 thousand in tools (not bike specific, but still), and id be damned before Id buy a chain measuring tool.
> 
> Its like buying a special 30 dollar cereal eating utensil when you've got a drawer full of spoons.


Ditto on the tools (more like $25K) - I was an auto mechanic for 10+ years.

For my own use a ruler is fine. But I have to be able to show customers that their chain is bad. A go/no go tool does that without me needing to explain pin wear, measurements, and such.

Of course, I also LOVE buying tools. I don't even want to think about how far into debt I was with Snap-On and Matco....


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## pdainsworth

We have a new KMC digital chain wear indicator at the shop. It works, and it's very... well, digital. It makes it easy to say yes or no, this chain is worn. It also lends a certain cache to the service area. To be truthful, though, a good/no good tool works just as well and costs a hell of a lot less.


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## Mike T.

Here's mine. This is the best - cut from a Dollar Store tape measure. It works perfectly.


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## Stogaguy

*+1 for the mechanic's ruler*

I will throw in the the fans of the ruler method. For me it just works better and seems more accurate than special gages.

I own a Park go/no-go gage and consider it only a rough indicator, and as such next to worthless. If I really want to know, I pull the chain and measure on the bench with a metal ruler.

For shop use, I can see the value of the "official" looking go/no-go gage. This produces an unambiguous result to show customers and avoids having to explain anything technical to them. The fact that the result may not be as accurate as it could be is really beside the point. It gets people to change worn chains. This, in turn, makes their bikes work better and they go away happy. For a shop, happy customers is what it is all about...


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## balatoe

I bought a Wipperman chain measuring tool. It works great! There is no confusion at all. If the center of the measuring tool touches the chain, then it's time to replace the chain.


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## MisterMike

*I use a ruler but maybe NOT anymore*

I use a ruler but in the latest issue of Velonews Lennard Zinn warns against it since in his words _"...only measures the outside dimensions of the chain and does not indicate how much worn rollers wallow around worn bushings and pins"_ He goes on to recommend a few tools and talks about the importance of a tool to push outward against rollers when measuring. He recommends the ProGold chain indicator, or the Rohloff Chain Checker to any other chain-elongation gauge


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## Mike T.

MisterMike said:


> I use a ruler but in the latest issue of Velonews Lennard Zinn warns against it since in his words _"...only measures the outside dimensions of the chain and does not indicate how much worn rollers wallow around worn bushings and pins"_ He goes on to recommend a few tools and talks about the importance of a tool to push outward against rollers when measuring. He recommends the ProGold chain indicator, or the Rohloff Chain Checker to any other chain-elongation gauge


Zinn's not in the business of insulting a whole industry of chain-gauge makers and recommending totally acceptable el-cheapo chain measuring methods. I'm sure he knows which side his bread is buttered. The ruler method has not failed anyone in decades - long before they came along with hi-tech solutions looking for problems.


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## C-40

*the facts...*

Any tool that measures between the rollers gives a mixed reading of elongation and roller wear that is worthless.

If you want to measure elongation, which is the true change in chain pitch, then use a 12" or longer precision rule. If you want to know how much roller wear has occured, use the internal measuring tips of some dial or digital calipers and compare the reading to the same brand of new chain, or the links that were removed from the chain when it was sized. Not all brands measure the same. A Campy chain may only meaure about .200 inch between the rollers, when new, but a Shimano or KMC might measure in the .210-.215 inch range.

It is rare for roller wear to be an issue, except with Campy chains. Campy chains may elongate so little that they will measure almost like new, even after 6,000 miles of use. A chain with that much use might have a the distance between the rollers increased by .0350-.040 inch and a side clearance that's nearly twice the original amount. In other words, the chain is shot, even though it has little elongation.


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## rx-79g

I'm going to throw in with the worthless, industry shilling, foolhardy roller wear believers conspiracy. Cog wear is caused by increased space between the contact point on the cogs, which is the rollers, not the pins running inside the rollers. Rollers wear due to friction. Chains elongate due to creep. Both make the rollers further apart (especially when curved around the cogs), but are caused by different forces and environments.

So if you want to measure only one of two things that put your chain out of pitch with the cogs, use a ruler. If you want to know about the geometry of the part that is actually rubbing against your chain, measure the rollers.

The main fuss people have to the Chain Checkers is that they show "wear" before there is any. But it isn't a wear monitoring device - it's a go/no go guage.

Funny how people like to quote Zinn about things like crank length (he sells cranks), but when he talks about some product he doesn't make he's a big liar.

I use whatever cheap chain checker was on sale. It shouldn't matter - they all measure the same thing.


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## FBinNY

*Any 12" ruler *with a reliable 0" and 12" mark is more accurate than any of the little devices you can buy. A 12" plastic schoolbook ruler is accurate enough for this job as long as it's a bit longer than 12" so the 0 and 12" marks aren't at the worn ends.


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## Kerry Irons

*Creepy*



rx-79g said:


> Chains elongate due to creep.


Now that's news. Creep is when the material actually deforms (like if you push on soft clay). I am not aware that this ever happens to hardened steels like those used in chain side plates. Everything I have ever read says that chains elongate due to wear at the pins.


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## Mike T.

FBinNY said:


> *Any 12" ruler *with a reliable 0" and 12" mark is more accurate than any of the little devices you can buy. A 12" plastic schoolbook ruler is accurate enough for this job as long as it's a bit longer than 12" so the 0 and 12" marks aren't at the worn ends.


That's why my dollar store one, above is marked off at the 10" and 22" marks. Simple. Maybe too simple.


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## mudrock

Zinn has a point when he says roller wear cannot be ignored. The drivetrain teeth engage the rollers, not the pins, so roller-and-bushing wear will affect chain elongation, in respect to where it contacts the teeth, just like pin wear will. Which wears faster? Pins and bushings are hardened steel, the rollers aren't. There are a lot of parts to a chain, and other things wear beside the pins. A Park wear checker works just fine for it's intended purpose.

Those who ascribe cynical motivations to Zinn are being careless with their judgements. He makes cranks because he's a tall guy, builds frames for other tall people, and saw the industry limit of 175mm (except for Campy) too short. People who make things themselves when the industry doesn't are enterprising, and deserve your respect. He is also well known to mix-and-match drivetrain components, coming up with solutions to save his readers money. Mike T.'s comment about Zinn not wanting to offend anyone is baloney.


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## Mr. Versatile

Why bother with all this nonsense? Just install a brand new $60 chain once per month and your worries will be over.


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## looigi

Mr. Versatile said:


> Why bother with all this nonsense? Just install a brand new $60 chain once per month and your worries will be over.


I recently got a ProGold chain measuring tool to play with after using a machinist's ruler for years. There are arguments both ways as to whether or not there is benefit to including roller wear into the measurement. However, rather trying to stretch the use of a high end chain, shop around and you can find Shimano 105 or Ultegra and equivalent SRAM or KMC 10-speed chains for <$30. Order a few to have on hand and when it doubt, slap on a new one. Heck, why even bother cleaning or lubing them? 

(kidding about that last part)


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## C-40

*wrong...*

Now that post really exposes your ignorance on this subject. Chains elongate due to wear between the pins and bushings formed into the inner side plates. There is no such thing as "creep".

Roller wear has no effect at all on the chain's length.

Many chain checkers will show a brand new chain to have .25% elongation or half worn out. Even if you subtract the false wear and use the chain until the tool reports .75% elongation, the reading still combines roller wear with elongation and the result can be a reading that's still nearly twice the true elongation.

About the only thing that you accidentally got right is that roller wear can contribute to cog wear. One expert claimed that only elongation (change in the .500 inch pitch) was relevant to cog wear, but I've worn cogs enough that they would not mate with a new chain, after using a single Campy 10 chain with a cassette for 6,000 miles. The true elongation was less than .2% (measured with an accurate full length gage), but the roller spacing had increased from it's original .200 inch to about .240 inch. I took that chain apart and measured the roller OD and ID. The OD was about .005 inch smaller and the ID was about .010 inch larger.

If you measure a new Shimano ro KMC chain you will find that the space between the rollers is in the .210-.215 inch range. That's why those chain checkers show the chain to have .25% elongation, when new. If you check a Campy chain, it would show close to zero wear when new. All brands will still have the same .500 inch pitch when new, so the tool is wrong.


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## Mike T.

C-40 said:


> Now that post really exposes your ignorance on this subject. Chains elongate due to wear between the pins and bushings formed into the inner side plates. There is no such thing as "creep".
> 
> Roller wear has no effect at all on the chain's length.
> 
> Many chain checkers will show a brand new chain to have .25% elongation or half worn out. Even if you subtract the false wear and use the chain until the tool reports .75% elongation, the reading still combines roller wear with elongation and the result can be a reading that's still nearly twice the true elongation.
> 
> About the only thing that you accidentally got right is that roller wear can contribute to cog wear. One expert claimed that only elongation (change in the .500 inch pitch) was relevant to cog wear, but I've worn cogs enough that they would not mate with a new chain, after using a single Campy 10 chain with a cassette for 6,000 miles. The true elongation was less than .2% (measured with an accurate full length gage), but the roller spacing had increased from it's original .200 inch to about .240 inch. I took that chain apart and measured the roller OD and ID. The OD was about .005 inch smaller and the ID was about .010 inch larger.
> 
> If you measure a new Shimano ro KMC chain you will find that the space between the rollers is in the .210-.215 inch range. That's why those chain checkers show the chain to have .25% elongation, when new. If you check a Campy chain, it would show close to zero wear when new. All brands will still have the same .500 inch pitch when new, so the tool is wrong.


Agree. I'll show everyone what contributes to chain elongation. This pin was from the worst worn chain I've ever seen The guy stood on the pedals, the chain skipped on the big chainring (OMG!) and he went over the bars. This one measured +3/8" over the 12" length. My max is 1/16th over. Any roller wear would be minuscule compared to this. Enjoy -


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## e39540is

I have no problem at all replacing a chain if it is in question on my bikes. The reason I want to measure chain length is because I am working on a bike for a friend, and I want a quick way to show her that her chain has stretched, which has ruined her chainrings, and cassette. All of the teeth are shark finned, and it is jumping when she stands. 

I see a lot of you that recommend just using a ruler, but isnt that just measuring the pin to pin, and not what actually causes wear on the cassette, and chaingrings which is the distance between rollers?


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## mudrock

When chains wear, it is mostly at the pins, which elongates the chain (that is, pin-to-pin distance, from one outer link to the next, increases), which accelerates wear of the teeth. The chain doesn't actually "stretch": the plates don't wear at all. The rollers do wear, but that doesn't contribute to elongation of the chain, so roller wear is a nonfactor regarding tooth wear.


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## mudrock

double post


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## Kerry Irons

*False concept*



mudrock said:


> Zinn has a point when he says roller wear cannot be ignored. The drivetrain teeth engage the rollers, not the pins, so roller-and-bushing wear will affect chain elongation, in respect to where it contacts the teeth, just like pin wear will. Which wears faster? Pins and bushings are hardened steel, the rollers aren't. There are a lot of parts to a chain, and other things wear beside the pins. A Park wear checker works just fine for it's intended purpose.


You're not thinking correctly about this. Picture two chains, one with roller wear but no elongation, and the other with elongation but no roller wear. The chain with no elongation would simply be "displaced" relative to the normal centering of the pins relative to the cog teeth, but would not apply any different wear forces to the cog teeth than a new chain would. Shifting might be dodgy, but no effect on cog wear.

The elongated chain would put higher loads on the first engaged cog teeth because the subsequent chain links would be "farther" from that first cog than with a chain that was not elongated. The elongagated will wear the cassette faster. While both chains might measure the same with a chain checker, they cause substantially different modes of cassette wear.


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## mudrock

Yes, you're right. I've since read this discussion by wheel builder extraordinaire Jobst Brandt, and it's clear to me that roller wear does not affect elongation and thus has no affect on tooth wear.

http://pardo.net/bike/pic/fail-004/000.html

The only chain checker he recommends is the Shimano, because it takes roller wear out of the chain measurement.


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## rx-79g

Kerry Irons said:


> You're not thinking correctly about this. Picture two chains, one with roller wear but no elongation, and the other with elongation but no roller wear. The chain with no elongation would simply be "displaced" relative to the normal centering of the pins relative to the cog teeth, but would not apply any different wear forces to the cog teeth than a new chain would. Shifting might be dodgy, but no effect on cog wear.
> 
> The elongated chain would put higher loads on the first engaged cog teeth because the subsequent chain links would be "farther" from that first cog than with a chain that was not elongated. The elongagated will wear the cassette faster. While both chains might measure the same with a chain checker, they cause substantially different modes of cassette wear.


Actually, you're missing how this works, because you're thinking about the chain linearly. 

In reality, the chain is wrapped around a circular cog. When the rollers fit the pins, both have the same pitch or spacing. But when the rollers are loose around the pins, the pins can sink further between the teeth (smaller radius) and the rollers are at a different, larger radius. Since they occupy different radii, their circumference (2 x Pi x r) and pitch become different. Once the chain straightens up again it isn't a problem, but bikes don't have cogs that are flat sided.

Pins do indeed become worn, but wear largely from roller contact and less from plate contact, so, again, a ruler isn't going to show you all the pin wear (just the stuff that makes the inner plate holes looser), and any creep in the sideplates.


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## rx-79g

Mike T. said:


> Agree. I'll show everyone what contributes to chain elongation. This pin was from the worst worn chain I've ever seen The guy stood on the pedals, the chain skipped on the big chainring (OMG!) and he went over the bars. This one measured +3/8" over the 12" length. My max is 1/16th over. Any roller wear would be minuscule compared to this. Enjoy -


BTW, all the wear shown on this pin is in the roller area. It is not possible to see a wear line between the inner and outer (fixed) plates on this pin.

What does that tell us? That chains get longer due to dimensional changes in the links, not wear on the pins. I'll leave that to my betters to decide whether that is because the inner plate is wearing or both plates are stretching - I don't think it would be easy to tell - unless you do things like I do - put a dial caliper on it.


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## C-40

*wrong again....*



rx-79g said:


> BTW, all the wear shown on this pin is in the roller area. It is not possible to see a wear line between the inner and outer (fixed) plates on this pin.
> 
> What does that tell us? That chains get longer due to dimensional changes in the links, not wear on the pins. I'll leave that to my betters to decide whether that is because the inner plate is wearing or both plates are stretching - I don't think it would be easy to tell - unless you do things like I do - put a dial caliper on it.


The pin in the picture has a huge ridge in the center where there is a gap between the two bushings formed into the inner side plates. When a chain reaches .5% elongation each pin and bushing pair has a combined wear of .0026 inch. Multiply that by 24 pins and you get 1/16" per foot. 

Chain elongation is absolutely not caused by the side plates stretching.

Here are some more facts. The rollers do not touch the pins, they only touch the bushing formed into the inner side plates. Take a link apart and look at the inner plates. The stamping process creates a tubular shape. The ID is the bushing for the pin and the OD is the shaft that the roller spins around.

I'll also correct another poster's comment about roller wear. It's usually much larger than the wear on the pins, particularly on the ID of the roller. The Campy chain that I measured after 6,000 miles of use had a reduction in the OD of about .005 inch and the ID was about .010 inch larger. Both values are greater than the pin/bushing wear.


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## C-40

*wrong again....*



rx-79g said:


> Actually, you're missing how this works, because you're thinking about the chain linearly.
> 
> In reality, the chain is wrapped around a circular cog. When the rollers fit the pins, both have the same pitch or spacing. But when the rollers are loose around the pins, the pins can sink further between the teeth (smaller radius) and the rollers are at a different, larger radius. Since they occupy different radii, their circumference (2 x Pi x r) and pitch become different. Once the chain straightens up again it isn't a problem, but bikes don't have cogs that are flat sided.
> 
> Pins do indeed become worn, but wear largely from roller contact and less from plate contact, so, again, a ruler isn't going to show you all the pin wear (just the stuff that makes the inner plate holes looser), and any creep in the sideplates.


You should take a chain apart, since you obviously do not understand what parts contact each other. The rollers do not contact the pins at all - they contact the inner side plates only. 

A ruler will show you ALL of the wear on the pins and bushing IDs.

The wear on the rollers does NOT change the chain pitch. This is obvious if you measure the distance between the roller of a Campy chain and compare it to a Shimano or KMC. There is a huge difference in the space between the rollers, when new, yet they will both have exactly the same overall length. A new Campy chain will measure about .200 inch between the rollers and a Shimano/KMC will be in the .210-.215 inch range. If the chain pitch was affected by this difference, the Shimano chain would be over an inch longer than a Campy chain - like it was stretched by 2%.

Chains do not contact the teeth is a circular pattern. The contacts are actually a series of short straight lines, not arcs, as you suggest.


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## roadie01

I agree with loogie it's much simpler to just replace your chain at regular intervals. I typically replace mine twice per year, once in May after a wet, dirty spring (I can't afford a winter / wet bike right now) then again in September after a long summer of riding and a couple of thousand miles. 

As previsouly stated here chain "stretch" is caused by wear, more friction accelerates wear. Which is why I'll replace my chain after a hard spring. 
In September I typically will do a double centruy race and want the bike to be in perfect working order.


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## mudrock

rx-79g said:


> Actually, you're missing how this works, because you're thinking about the chain linearly.
> 
> In reality, the chain is wrapped around a circular cog. When the rollers fit the pins, both have the same pitch or spacing. But when the rollers are loose around the pins, the pins can sink further between the teeth (smaller radius) and the rollers are at a different, larger radius.


A new chain already contacts the teeth at the bottom of the "valley." As the chain elongates, it contacts the teeth farther up its profile. Surely you've seen this by wiggling a worn chain on a chainring. It doesn't seat at the bottom anymore. This is what accelerates wear of the teeth. 



> Pins do indeed become worn, but wear largely from roller contact and less from plate contact, so, again, a ruler isn't going to show you all the pin wear (just the stuff that makes the inner plate holes looser), and any creep in the sideplates.


Check out the link from my previous post. It describes wear better than I could. The only cause of elongation is wear of the pins, and the only moving part that contacts pins is the bushing of the inner link. I also was ignorant of how it wears until I read this.


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## mudrock

http://www.youtube.com/watch?v=RGjcD8xEu8o

Fine for you, but you could be throwing your money away. Different chains wear at different rates. The Srams are the worst, according to this video. I've heard the KMC chains, like the one sold under the Nashbar label, lasts a long time. This video is 10 months old, and Wippermann says there will be updates, but I haven't seen one yet. The Wippermann comes out on top (natch, it's their video). My fav, the KMC hasn't been tested yet

Better to keep your chain clean and use accurate measurements, then to rely on periodic replacement. I have 3 bikes that all get a lot of use; it can get expensive.


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## rx-79g

C-40 said:


> You should take a chain apart, since you obviously do not understand what parts contact each other. The rollers do not contact the pins at all - they contact the inner side plates only.
> 
> 
> Chains do not contact the teeth is a circular pattern. The contacts are actually a series of short straight lines, not arcs, as you suggest.


You are 100% correct - I got my chain mechanics wrong about how they go together.



However, the arc that the chain conforms to, even if formed of straight lines, still means that rollers and pins will occupy different locations on the teeth when there is large roller wear. That difference location difference is going to mean a difference in pitch between the two that will cause the rollers to not sit squarely between the teeth - despite a lack of elongation. The pins and teeth are both spaced 1/2" apart, but only at the center of the valleys. At the base of the valleys the pitch is less than 1/2", and that's where the pins try to go go when the rollers are worn.


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## al0

C-40 said:


> Any tool that measures between the rollers gives a mixed reading of elongation and roller wear that is worthless.


That's true - almost, as you have to take in account that it measures a wear of only 2 rollers (those tool's pins contact) and all ping and bushing between the pins. So if the tool is long enough a measurement error would be tolerable. Unfortunately, most available chain-checkers are noticeably shorter than they can be.

A ruler may be more accurate but if and only if the chain is under some strain (say 100Nm). 



> It is rare for roller wear to be an issue, except with Campy chains. Campy chains may elongate so little that they will measure almost like new, even after 6,000 miles of use.


Its funny bit recent tests from German TOUR magazine (2011/02) show otherwise -
roller wear is a much bigger issue for Shimano chains than for Campy ones (they run the chains on the stand for about 100 hours under varying conditions - water, sand, ...) and then checked them with a chain checker and with a ruler. To put it short for Campy chains both methods have shown consistent results (either both "go" or both "no go"), for Shimano chains a ruler method gave "go", a chain checker - "no go".

Another funny thing that the most wear-resistant in these tests were new (x700) Shimano chains, especially DA and 105) with Campy close next. The worst were SRAM.


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## C-40

*not quite...*

The rollers do contact the cogs in a different point as the chain elongates, but the roller always self-center and do not affect the chain pitch. As elongation occurs the contact point on the teeth gets higher and higher, until the chain goes over the top of the tooth with really extreme wear.

Even Jobst Brandt did not address the possible situation where there is litte elongation, but lots of roller wear. Campy chains are the only ones where I have seen this. When I used a Campy chian for 6,000 miles, it had very little elongation, but my most-worn cog skipped when I put a new chain. That proved to me that new-chain skip could occur even if the only chain ever used with the cassette never came close to .5% elongation.


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## Kerry Irons

*Simple?*



roadie01 said:


> I agree with loogie it's much simpler to just replace your chain at regular intervals.


Are you suggesting that holding a ruler up to your chain is somehow "too complicated" and therefore you have to default to a chain replacement schedule, regardless of mileage, riding conditions, or chain quality? I guess that makes sense - NOT!


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## rx-79g

C-40 said:


> The rollers do contact the cogs in a different point as the chain elongates, but the roller always self-center and do not affect the chain pitch. As elongation occurs the contact point on the teeth gets higher and higher, until the chain goes over the top of the tooth with really extreme wear.
> 
> Even Jobst Brandt did not address the possible situation where there is litte elongation, but lots of roller wear. Campy chains are the only ones where I have seen this. When I used a Campy chian for 6,000 miles, it had very little elongation, but my most-worn cog skipped when I put a new chain. That proved to me that new-chain skip could occur even if the only chain ever used with the cassette never came close to .5% elongation.


Well, they won't self center if they are under tension. It looks like this:









This image shows rollers worn and unworn and the pins evenly spaced with zero elongation.

When the pins settle low into the cogs because of worn rollers, the pitch of the cogs effectively changes. That causes the chain to get long where it enters and leaves the cogs, causing wear that is similar to elongation without any.


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## Mike T.

OMG, this bloody thread, like every bi-monthly chain wear argument, is hilarious. There's relatively intelligent people arguing about what method of figuring out whether a chain is worn out or not is best. A bike chain is such a low-tech mechanical implement that the simplest method of gauging its wear is just fine. All chains are a set size when new (OMG I might regret saying that!) and a rule-of-thumb that's decades old for judging their wear should be an accepted standard. But then people come along who want to mystify it and make a special tool for just this purpose. Then more companies jump on that bandwagon and then low & behold, those who need this kind of stuff in their lives start debating what's better. I think I need a stiff drink - after I've patted my dollar store piece of steel tape-measure.


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## rx-79g

Mike T. said:


> OMG, this bloody thread, like every bi-monthly chain wear argument, is hilarious. There's relatively intelligent people arguing about what method of figuring out whether a chain is worn out or not is best. A bike chain is such a low-tech mechanical implement that the simplest method of gauging its wear is just fine. All chains are a set size when new (OMG I might regret saying that!) and a rule-of-thumb that's decades old for judging their wear should be an accepted standard. But then people come along who want to mystify it and make a special tool for just this purpose. Then more companies jump on that bandwagon and then low & behold, those who need this kind of stuff in their lives start debating what's better. I think I need a stiff drink - after I've patted my dollar store piece of steel tape-measure.


When chains were $6 and freewheels $20, I would have agreed with you - any old method would be fine. Current cassette and chain prices suggest that they are no longer low tech, so I don't see why consulting a $6 tool is "mystical". And if you do suggest that it might be a good idea to consider the WHOLE chain, you have to contend with the ruler police and be talked to like you're an idiot.

I don't care what anyone chooses to do, but it is nice if the topic can be discussed honestly.


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## TomH

Anyone ever see a chain thats within spec, measuring the ruler way, thats worn enough to cause any ring or cassette damage? 

All this roller talk is great, but ive seen no evidence that this wear actually occurs faster than a chain will "stretch" as indicated by a ruler. The ruler method flat out works. 

If the person you're showing a worn chain to cant read a standard ruler, they're probably not going to trust your bike tool either (but really, who cant read a ruler?).


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## PlatyPius

TomH said:


> Anyone ever see a chain thats within spec, measuring the ruler way, thats worn enough to cause any ring or cassette damage?
> 
> All this roller talk is great, but ive seen no evidence that this wear actually occurs faster than a chain will "stretch" as indicated by a ruler. The ruler method flat out works.
> 
> *If the person you're showing a worn chain to cant read a standard ruler, they're probably not going to trust your bike tool either (but really, who cant read a ruler?).*


It's not a matter of not being able to READ it, it's a matter of knowing what the f#[email protected] it means.

Option 1: Explain to the customer that 1/16" is kinda bad and it should be replaced. 1/8" is really bad, and you should replace the chain and cassette. Customer considers 1/16" in their head and decides I'm trying to rip them off. How the hell could 1/16" make anything bad?

Option 2: Put old Park Red/Green chain gauge on the chain in front of customer. Turn thumbwheel. Show customer that the chain is in the red zone. Grunt "Green good, Red Bad!". Customer has no conflicts over tiny measurements and buys a new chain. If the tool flops around in the chain, they buy a new cassette, too.

I have used both options in the shop(s). #1 tends to produce the result mentioned. Ditto #2.

The typical person gets on their bike and goes. They don't check anything, they don't maintain anything. That's what I'm for, right? They'll ride that chain right into the ground; never noticing the dry creak coming from it until it either breaks or it skips when they are standing on the pedals. They don't care about "Chain Measuring for Anal Retentives", they care about getting their bike fixed as cheaply as possible. Me, I care about fixing the bike and not letting it go out with worn out parts on it. If I give them a tiny number and tell them that means their chain is toast, 60% (number pulled from ass, but probably accurate) are going to "wait until next time" - even though the chain is only touching 2 teeth of an 18 tooth cog. If I show them "Red Bad!", 98% are going to buy the chain/cassette.


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## C-40

*No....*

If rollers with a smaller ID or larger ID caused a change in pitch, then a Shimano or KMC chain would have 2-3% elongation when new. What the drawing illustrates is an elongated chain with wear on the pins and inner plate bushings. The person who drew that does not understand the difference between roller wear and pin/bushing wear that causes elongation. That person had good intentions, but incorrectly identified the wear as roller wear.

My extremely worn Campy chain had less than .2% elongation after 6,000 miles. It was about 1/16" longer than new, over the full 53 inch length. That's only .0006 inch of wear per link.

In contrast, the ID of the rollers was about .010 inch larger than new. The roller spacing increased from .200 inch to .240 inch. That .040 inch value is a mixture of the wear on both the OD and ID of two rollers and two side plate bushings, or six wear surfaces. Even divided by 6, the average is over 10 times the wear on the pins and their bushings.


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## Clay L

How many pages are we gonna get on this topic? After i read the first 3 posts everything else is just redundant. Just go with what works for you or when it breaks i guess you went a little too far.


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## mudrock

*Let go of that concept*



rx-79g said:


> When the pins settle low into the cogs because of worn rollers, the pitch of the cogs effectively changes. That causes the chain to get long where it enters and leaves the cogs, causing wear that is similar to elongation without any.


New chains already mesh with the teeth at the bottom of their radii: a chain cannot "settle any lower into the cogs" than it will when new. You can easily check this yourself. With a new chain on the large (unworn) chainring, try to lift the chain by pulling the chain off the ring, towards the front of the bike. There will be no slack. Now do this with a worn chain, and it will be loose. The worn pins elongated the pitch of the chain, so it cannot mesh well with the teeth. Anyone who has worked in bike shops knows this as a matter of fact. 90% of the repairs that come in the door have worn-out chains, and the first thing any mechanic will do is grab the chain at that spot to check for wear.


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## rx-79g

mudrock said:


> New chains already mesh with the teeth at the bottom of their radii: a chain cannot "settle any lower into the cogs" than it will when new. You can easily check this yourself. With a new chain on the large (unworn) chainring, try to lift the chain by pulling the chain off the ring, towards the front of the bike. There will be no slack. Now do this with a worn chain, and it will be loose. The worn pins elongated the pitch of the chain, so it cannot mesh well with the teeth. Anyone who has worked in bike shops knows this as a matter of fact. 90% of the repairs that come in the door have worn-out chains, and the first thing any mechanic will do is grab the chain at that spot to check for wear.


I gave you an illustration of how worn rollers and chain tension from riding can make the chain poorly fit the cogs - look at the picture. 

I worked in shops for 6 years.


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## rx-79g

C-40 said:


> If rollers with a smaller ID or larger ID caused a change in pitch, then a Shimano or KMC chain would have 2-3% elongation when new. What the drawing illustrates is an elongated chain with wear on the pins and inner plate bushings. The person who drew that does not understand the difference between roller wear and pin/bushing wear that causes elongation. That person had good intentions, but incorrectly identified the wear as roller wear.
> 
> My extremely worn Campy chain had less than .2% elongation after 6,000 miles. It was about 1/16" longer than new, over the full 53 inch length. That's only .0006 inch of wear per link.
> 
> In contrast, the ID of the rollers was about .010 inch larger than new. The roller spacing increased from .200 inch to .240 inch. That .040 inch value is a mixture of the wear on both the OD and ID of two rollers and two side plate bushings, or six wear surfaces. Even divided by 6, the average is over 10 times the wear on the pins and their bushings.


There is no elongation in the illustration. The pin distances are fixed, as they would be on a chain with no pin related wear. The illustration just shows how rollers that are worn can allow the pins to settle lower into some parts of the cog, forcing the chain into high wear contact in other areas.

I made the pictures, and I chose to show the chain fully seating at the 10 o'clock position, but that is just for illustration. It might happen closer to 12:00 and put all the out of phase wear at 6:00. Regardless, cog wear occurs when the chain doesn't mesh correctly and rubs the tops and sides of the teeth.


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## wim

rx-79g said:


> I made the pictures, and I chose to show the chain fully seating at the 10 o'clock position, but that is just for illustration.


Nice drawings, rx. I've been asked some time ago to translate the Rohloff chain wear article at the link, but have never gotten around to it. Still, take a look at the illustrations, they're instructive. The elongation values in the text are averages because of the typical short-long-short link wear pattern. Arrows are force vectors (direction and magnitude). All length dimensions are millimeter. 

Scroll down for illustrations:

Bild 1 (illustration 1)... new chain, new cog
Bild 2........................worn chain, worn cog
Bild 3........................new chain, worn cog
Bild 4........................worn chain, new cog

Black rollers = low chain tension
Light rollers = high chain tension

http://www.rohloff.de/uploads/media/Technische_Infos_Kette.de.pdf


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## mudrock

rx-79g said:


> I gave you an illustration of how worn rollers and chain tension from riding can make the chain poorly fit the cogs - look at the picture.


Okay, we'll use you're pictures for reference.

1) worn rollers alone will not change the pitch of the chain, because each roller wears the same amount. The distance from one pin to the next will not change, thus the pitch remains the same. I'll grant you that worn rollers might make engagement a little sloppy, but the point of contact will not change as a result. The force the taut chain puts on the cog will be in the same spot, whether new or worn (assuming no change in pin wear). You assume a new chain meshes perfectly with a new cog, with no voids, and that is an error in your illustration (refer to the Rohloff illustrations for example). That isn't the case. Shifting would be terrible it that were so.

2) a worn pin, however, changes the distance from outer link to the next pin on the inner link, because the radius of the pin the inner link rotates on is now smaller. The distance from pin to pin on the outer link does not change, because the links themselves do not "stretch." So you have alternating links with slightly elongated pitch. That is what causes the wear.


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## rx-79g

mudrock said:


> Okay, we'll use you're pictures for reference.
> 
> 1) worn rollers alone will not change the pitch of the chain, because each roller wears the same amount. The distance from one pin to the next will not change, thus the pitch remains the same. I'll grant you that worn rollers might make engagement a little sloppy, but the point of contact will not change as a result. The force the taut chain puts on the cog will be in the same spot, whether new or worn (assuming no change in pin wear). You assume a new chain meshes perfectly with a new cog, with no voids, and that is an error in your illustration (refer to the Rohloff illustrations for example). That isn't the case. Shifting would be terrible it that were so.
> 
> 2) a worn pin, however, changes the distance from outer link to the next pin on the inner link, because the radius of the pin the inner link rotates on is now smaller. The distance from pin to pin on the outer link does not change, because the links themselves do not "stretch." So you have alternating links with slightly elongated pitch. That is what causes the wear.


I'm not saying that "pitch" is actually changing. I'm saying that the rollers are a spacer that makes the chain pitch match the cog pitch. 

"Pitch" in terms of a cog mean that the center point of the valleys are exactly 1/2" apart from each other at one particular radius. If the radius is less than that number, then the pitch stops being 1/2". If the rollers aren't holding the pins out at the right radius, then the pins under the greatest load will attempt to go to the lower radius - and the following pins will have to go off-pitch to make up for it. That's what my illustration shows - the pins at 10:00 are too close in to the cog center, so they create slack on the 6:00 and 12:00 position.

Imagine a 1/2" chain that has 1/8" rollers. Would that chain operate normally on a cog built for normal rollers? Not when there is a load only on one end of the chain.


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## C-40

*well...*

What I see is rollers near the last few teeth riding higher, which is what happens when a chain elongates. An elongated chain rides higher on the teeth and concentrates the load on the last tooth engaged. Eventually, it will either break off a tooth due to the heavy loading or skip over the top of the teeth. That will not occur due to roller wear alone. That's why the different brands of chains can function well, even though the difference in the roller spacing is huge, compared to the allowable difference in chain pitch. 

You can draw anything, but proving that the drawing is correct is something else. A worn roller would be be drawn with a larger ID and smaller OD. There would also be wear on the inner plate bushing. I don't even see inner plates, only what I would assume are outer plates and pins. The rollers do not touch the pins. All you've got there is a flawed and over-simplified drawing.

You can find drawings and specifications on the internet with the proper definition of the tooth profile. To do an accurate analysis would require some good drawing software, like autocad. I used that type of software (microstation) for many years, to draw precision parts for nuclear weapons, when I was in that business.


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## rx-79g

C-40 said:


> What I see is rollers near the last few teeth riding higher, which is what happens when a chain elongates. An elongated chain rides higher on the teeth and concentrates the load on the last tooth engaged. Eventually, it will either break off a tooth due to the heavy loading or skip over the top of the teeth. That will not occur due to roller wear alone. That's why the different brands of chains can function well, even though the difference in the roller spacing is huge, compared to the allowable difference in chain pitch.
> 
> You can draw anything, but proving that the drawing is correct is something else. A worn roller would be be drawn with a larger ID and smaller OD. There would also be wear on the inner plate bushing. I don't even see inner plates, only what I would assume are outer plates and pins. The rollers do not touch the pins. All you've got there is a flawed and over-simplified drawing.
> 
> You can find drawings and specifications on the internet with the proper definition of the tooth profile. To do an accurate analysis would require some good drawing software, like autocad. I used that type of software (microstation) for many years, to draw precision parts for nuclear weapons, when I was in that business.


What your seeing is a very basic geometrical demonstration that changing just one roller dimension can cause the spacing to mismatch. People tell me it can't work like that - well there it is - the illustration is not an artists conception - I measured the distance between pins and teeth to make it an accurate model.

OD roller wear and pin wear will only increase the out of phase condition, but the point was to show that roller wear alone _could_ cause the chain to wear on the cogs. And that is what the picture does - accurately models my reason for checking roller wear.


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## C-40

*well...*

I'll never convince you that you're wrong, just like your rant about stack and reach where you were also confused. 

A chain will not ride higher on the teeth due to roller wear - only due to elongation. That should be evident when you consider that pin/bushing wear of only 1.5-2% or .010 inch will cause chain skip. A chain that has a roller spacing increase of .040 inch or four times greater will work just fine. The two types of wear absolutely do not cause the same problem.

If your idea were true, then Shimano and KMC chains with .210-.215 inch roller spacing would cause more chain wear than brands that start out at only .200 inch. What's your rule for changing a chain based on roller wear?

A Campy chain might take 2000 miles or more to reach a spacing of .220 inch, which I consider to be about half worn. A Shimano or KMC chain might have a .220 inch spacing in a 1000 miles or less and a chain checker would (falsely) show that the chain had over .5% elongation.

Most often, a Shimano or KMC chain will elongate by .5% before severe roller wear occurs, and most people trash the chain at that point. Those who used a flawed chain checker would be tossing chains long before .5% of true elongation was reached, since roller wear is much larger than pin/bushing wear and it can double the reported "elongation". A check with a precision rule would prove that the true elongation is much less.


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## rx-79g

C-40 said:


> I'll never convince you that you're wrong, just like your rant about stack and reach where you were also confused.
> 
> A chain will not ride higher on the teeth due to roller wear - only due to elongation. That should be evident when you consider that pin/bushing wear of only 1.5-2% or .010 inch will cause chain skip. A chain that has a roller spacing increase of .040 inch or four times greater will work just fine. The two types of wear absolutely do not cause the same problem.
> 
> If your idea were true, then Shimano and KMC chains with .210-.215 inch roller spacing would cause more chain wear than brands that start out at only .200 inch. What's your rule for changing a chain based on roller wear?
> 
> A Campy chain might take 2000 miles or more to reach a spacing of .220 inch, which I consider to be about half worn. A Shimano or KMC chain might have a .220 inch spacing in a 1000 miles or less and a chain checker would (falsely) show that the chain had over .5% elongation.
> 
> Most often, a Shimano or KMC chain will elongate by .5% before severe roller wear occurs, and most people trash the chain at that point. Those who used a flawed chain checker would be tossing chains long before .5% of true elongation was reached, since roller wear is much larger than pin/bushing wear and it can double the reported "elongation". A check with a precision rule would prove that the true elongation is much less.


I didn't say that roller wear would cause "the same problem". I simply said that roller wear can contribute to cog wear due to the geometric mismatch worn rollers cause - that doesn't mean that they will skip.

What's my rule for changing the chain? Are you kidding - look at the thread title. I use a chain checker, and I use it because it shows when the combination of elongation and roller wear becomes too large. I replace the chain when it's about at "No go". 

What I don't do is use the chain checker to create graphs of chain wear or use it as a predictive tool. I don't put it on new chains, either. The one piece chain checkers aren't going to be very accurate anyway before the chain is at no go because they swing down into the chain - it's pretty damn difficult measuring the linear movement of round parts with a wedge shaped tool face. So applying "75% chain wear" back to the mileage is pretty pointless - they aren't necessarily linear. In all these debates people want to get upset about how the chain checker monitors the chain wear - almost no one posts examples of no go chains that are truly not putting wear on the cogs.


As to the Stack and Reach dig - we understand each other perfectly. You demonstrated the math necessary to utilize it, and I made the point that a system involving that much math isn't necessary or useful. No confusion there, unless you count all the times you, I and others flubbed that math.


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