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Chain Wear Measurements Tools: Myth Busted again!!


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I've always followed the online debates concerning the topic:


Myth: Do Chain Wear Measurement Tools give correct readings?




Result: Myth Busted !!!!



Earlier this month I was about to purchase one of these checkers, I know that they where slightly off but wanted one for the convenience. Thank goodness I opted to get a descent vernier instead.


So two weeks back I measured my "chain wear" using the vernier but like a chain wear tool - inside the links. On a (think it was 5") measurement I came to 0.47% and calculated that I had till the end of the month to get a new chain.


One new chain later.


So yesterday I lubed my old chain as I did not want to fit my new chain till I got my cassette remover (to install my new cassette as well). While lubing I noticed the amount of "play" on the link rollers.


So I decided to measure again but this time I measure correctly by doing the outer linkpin-2-linkpin measurement.


My chain wear came to 0,40% and not 0,47% as previously (by now it should have been 0,49% by my previous calculations).


Thats nearly a 20% variance.


This got me thinking why such a big variance, I would expected only perhaps 0.01%.


This got me thinking again and released why the Park Tool (and others) are so inaccurate: The length of the tool.


The shorter the length used to measure the "wear", the bigger the variance in the two methods due to the "play" on the rollers. The play, in inches, will remain the same regardless of how many links you measure. It will neither increase nor decrease - just remain constant.


Now if my original measurement that gave me a 0,47% (that was suppose to be 0,40%) was done over the correct 12" instead of 5" I would have gotten only a 0.03% (0.43%) and not a 0.07% (0.47%) variance in my reading - that would have given me at least 10% more life on my chain ~ about 200km more.



But getting back to the correct way and the incorrect way (using these nasty chain checkers) I see that I would have to had to toss my chain with at least 500km still left on it.



This explains, once again, why so many Hubbers through out the world cannot understand why their chains are measured as requiring replacement when they have only done a couple of km's around the block.



So yeah, next step is to get that Park Tool spoke ruler and mode JB style to check my chain. Smile


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Mr Brunson, I have good news for you. A very quiet young hubber and recently-graduated engineer and I have collaborated and designed the uber-chain tool. We've applied for a patent and will soon be able to show it off to the world.


You are almost correct in why these things are INaccurate but I'll summarise it in two points:


1) They measure from variable rollers that may, or may not have dirt underneath and.


2) The measuring distance is not long enough to dilute the measuring error. There is always a measuring error and when you're working with a 1% threshold as is the case here, you don't want to measure 1% over a short distance but rather over a long distance and so dilute the reading error.









Johan Bornman2010-05-20 11:34:12
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Hogwash. The Park Tools little Dingess is all about technique. You have to hold it delicately between 2 fingers and gently slip on and off. Closing your eyes and and slipping your tongue out assist with this delicate procedure.


Now if they could build a bottle opener into it it would make the ultimate multipurpose gadget.


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Thanks JB. My brain is in IT mode (exams this week) so my terminology is a bit scewed.


But I'll even buy a ruler if it has the JB stamp of opproval Wink


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so what is the p-value of all these percentages?




is it of any significance?ichnusa2010-05-18 14:06:44

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None what-so-ever !! WTF measure their chain all the time ?? It's like a HR monitor , either it works or it does not . If I think my chain is shot I replaced it , if I get chest pains while watching TV I get another beer . The chain on my bike is so "stressed " I had to put it on prozaks !! ooops sorry that should be stretched , whatever the case maybe I got a 4 year old chain that still turns the rear wheel and changes when I pull the lever .

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"I came to 0.47% and calculated that I had till the end of the month to get a new chain....."

"- that would have given me at least 10% more life on my chain ~ about 200km more."


Careful, this reasoning is quite flawed....thre are so many variable factors affecting chain wear (rider style; muddy condition - or not; et etc.)

To "calcualte " the time /distance that you have left ....will just waste your money when you actually dont't need to buy a new chain...


@JB....out with it!! when can I get one of those Uber tools? Will it replace my ss inch ruler, by making it more easy to calc the % wear?

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Cassie, I'm riding tar this month and feel comfortable on my reasoning. But I did see that one 30km ride through Kogelberg put some serious wear on my chain last year.


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