How to use a chain wear tool

[bpsmith]

I hope you weren't pulling my leg implying that we measure the entire chain. If you were, ha ha*, if you weren't, your astute observation is probably the root of most people's frustration using this method. One solution is to use a yardstick and cut off a piece of it but I've found a nice workaround. Partool's spoke ruler is a couple of 1/16th of an inch longer than 12 inches, giving you just enough to play with.

If you tweak the other side, the zero point with a file, you have a near-perfect chain measurement tool, other than the one I've - ahem - patented and am awaiting lucrative licensing deals.

Roller chains and sprockets are widely misunderstood, hence my book on the topic. Cough cough.




View attachment 115155

* I absolutely refuse to say LOL. I'd rather lick my chain clean than say it.

Was jesting, yes, of course. I was merely suggesting that a rule of only an inch long would hardly suffice. A rule of at least 12.5 inches, fair enough. I believe the follow up quote understood what I was getting it. Lol*

* couldn't resist, sorry

 

[gbb]

Further, a worn chain does not affect shifting at all. A good chain or a worn chain will shift equally good or bad on the same setup

So you're saying KMC, major chain manufacturer, a company that have probably invested multi millions, perhaps billions in R&D, testing etc etc....are wrong.
http://www.kmcchain.eu/MAINTENANCE
Particually the copied section below...
To check the chain’s elongation......
A worn chain has a negative effect on your drive train, not only a loss of shifting function, but when extremely worn, you even risk breakage.....

 

[Citius]

Obviously KMC has no interest whatsoever in ensuring people change their chains regularly. Anecdotally, I have never experienced worsening shift performance from a worn chain. It's quite possible that page was written by KMC's marketing people.

Although I did particularly like this bit - which should interest @bpsmith...

"Try to avoid a so-called ‘chain washing machine’ in combination with solvent. This will instantly ruin your chain."

To be fair, this should be taken about as seriously as the rest of the comments on that page, because it patently will not 'instantly' ruin your chain. But it's still a bit pointless though.

 

[bpsmith]

That is interesting @Citius. I use my cleaner tool with Citius Degreaser. Works a treat and chain looking great!

 

[Citius]

Don't let KMC hear you saying that...

 

[bpsmith]

It's a Shimano chain on the best bike, so not worried. :-O

 

[Yellow Saddle]

So you're saying KMC, major chain manufacturer, a company that have probably invested multi millions, perhaps billions in R&D, testing etc etc....are wrong.
http://www.kmcchain.eu/MAINTENANCE
Particually the copied section below...
To check the chain’s elongation......
A worn chain has a negative effect on your drive train, not only a loss of shifting function, but when extremely worn, you even risk breakage.....

Yes, that's exactly what I'm saying. The error you make is one of appeal to authority. Further, you completely ignore the affect of new chain sales from this bit of nonsense. As I said, you'll find no rational explanation on that website. I'll give you the counter argument. Attempt to punch holes in that, at least I can lay a foundation for my claim.

I doubt KMC invests billions in R&D. That's the type of budged reserved for defense and aerospace spending, not manufacture of a mature-technology commodity.

The shifting from one sprocket to another happens in the slack cycle of the chain i.e. underneath the sprockets. There the chain's length is variable because it is entirely determined by it's cleanliness and the derailer's tension spring. Whether it is long or short (worn or new), it simply slots onto the cogs with no effort. The tiny bity of extra lateral flexibility it gains when worn also has no effect since the derailer only pushes the chain as far as it determines. The lateral movement is thus not determined by the chain's flexibility (even a new chain has more flexibility than a derailer can throw) but by indexing settings.

As for strength. Chain pins wear in two grooves directly underneath the swaged bushings on the inner plates. These grooves wear at half the rate of the chain's elongation. The other half is in the bushing itself. Thus, when a chain is 1% elongated and way beyond it's service life, the pin's wear is only 0.5% of the elongation of that link. Consider that 100 links at 1% wear gives us a chain that's as long as a 101 link new chain. To be exact, the elongation is thus 1/2 inch. Divide that by 100 and you are approximately at half the dimension of the wear on the pin. The pin which is approximately 3.5mm thick when new, becomes 3.4mm thick when the chain is worn out. That would make it weaker but I do hope you get the point that the weakness is irrelevant, especially considering that a chain's weakest point is the riveted ends of the pin, which experience no wear or weakening in use at all.

KMC's argument that an extremely worn chain is weak, is stupid. Firstly, the definition for extremely is vague. An extremely worn chain will cause extremely worn sprockets which will literally flatten out before the chain approaches breaking point. The drivetrain stops operating when a chain approaches 3% wear and a point where the chain is unsafe is never reached.

I've said it before and I'll say it again. Marketing brochures and websites and bike magazines are not a good source of sound scientific information..

 

[Yellow Saddle]

Plus one for this, though for this distance a plastic ruler is fine if one doesn't possess a steel one. I can only assume that some people struggle with the challenge of counting 10 double links, measuring them accurately (in tension, along the line of the chain which you've aberationally put large to large), and then the maths of calculating how much more than 10 inches means a stretch of 0.75% (implying that the chain should be changed without undue delay).

Mathematically of course, your argument is sound. But, measurement with a crude instrument for small discrepancies is not as simply as extrapolating for a new length. The measuring error when working with a chain in-situ is large, there is a parallax error and the notion that your error is at least half of your smallest calibration. In a worst-case scenario the measuring error will therefore be larger than the elongation you're looking for. When you thus mathematically intrapolate when measuring a short section of chain, you increase the percentage error enormously. That's why the most accurate measurement is taken over the longest piece of chain possible. On a bicycle this section is available at the bottom run of the chain, when the front sprocket is large and the rear one small. This gives you an approximate 14 inch section. A good tool will take up all the available space. This is another reason why these short little commercially-available tools are inaccurate.

 

[gbb]

If you prefer a rule to measure, good on ya.
If you want ease of use, perilously quick results...use a chain wear tool.
No-one is going to die whichever method they use.
99% of people really dont care that much, they just want a method of measurement, either will do the job to one satisfactory level or another.Id agree a rule is better..
Do whats best for you.

 

[lpretro1]

Well said that man - most people just want a quick * 7 easy way of checking it out - worst case is you buy a new chain a wee bit early - it's not going to break the bank. Leave the other method for the anally retentive amongst us - my life is too short to be sitting doing calcs on my chain length - but if you wanna do so then please feel free!!

 

[Ajax Bay]

Leave the other method for the anally retentive amongst us - my life is too short to be sitting doing calcs on my chain length

Presumably, madam, if the 'other method' is using a ruler, you're connecting numeracy (can calculate 1% of 10 inches ???) with immodium-treatable and hopefully temporary condition. What proportion of the readership of this topic do you think cannot manage to calculate 1% of 10 inches, even if their life is short? I can see that "people just want a quick easy way of checking it out" but as per the title of this thread, using a chain wear tool seems less simple than using a ruler (on a good 10 inches, not "a short section of chain" btw). And you don't need a special tool.

@Yellow Saddle makes excellent points and is clearly an international GM in this discipline. In particular (for me) the points about measuring (in)accuracy are well made - I seek to mitigate that risk by care.

Heartily agree with @gbb

99% of people really dont care that much, they just want a method of measurement, either will do the job to one satisfactory level or another.Id agree a rule is better..
Do whats best for you.

 

[derrick]

Further, a worn chain does not affect shifting at all.

A new chain does shift better than a worn one.

 

[Ajax Bay]

A new chain does shift better than a worn one.

Why? Please deal with the lateral aspects of chain shifting, not the effect of a chain stretched beyond its sensible replacement point and assume the cassette is OK.
Clearly if the chain is stretched beyond its sensible replacement point and/or the cassette is worn out then there'll be problems, but these are not shifting ones per se.

 

[derrick]

A worn chain is a stretched chain

Why? Please deal with the lateral aspects of chain shifting, not the effect of a chain stretched beyond its sensible replacement point and assume the cassette is OK.
Clearly if the chain is stretched beyond its sensible replacement point and/or the cassette is worn out then there'll be problems, but these are not shifting ones per se.

 

[Ajax Bay]

Quoting the IGM:

The shifting from one sprocket to another happens in the slack cycle of the chain i.e. underneath the sprockets. There the chain's length is variable because it is entirely determined by it's cleanliness and the derailer's tension spring. Whether it is long or short (worn or new), it simply slots onto the cogs with no effort. The tiny bity of extra lateral flexibility it gains when worn also has no effect since the derailer only pushes the chain as far as it determines. The lateral movement is thus not determined by the chain's flexibility (even a new chain has more flexibility than a derailer can throw) but by indexing settings.

So @derrick you haven't made any effort to support your contrary assertion that: "A new chain does shift better than a worn one".