Workshop Stories: Chain Measure Tool

[Johan Bornman]

Someone here on The Hub got me one from Chainreaction for about R120 after tax and stuff.

http://www.chainreactioncycles.com/SearchResults.aspx?Search=park+ruler

 

[Cicada]

Then I wouldn't be too greedy to offer one @ R 110 for a brand new one? (I've got two)

By the way, I am in Bellville

 

[Guest Big H]

good question. johan' date=' i would like to see pics of the park tool measurements against those of the ruler. any chance?[/quote']

 

I am sure you would like to see it. Why not just do it yourself?   

 

Interesting to see that a Hubber called "roller" does not trust a ruler...... neither do I trust the part of his name that is "holy"!!!!!!!!!!!!

[Capricorn]

if measuring over a limited length of chain realizes errors of various values depending onthe measured length, isn't the best option to measure the whole chain as that will take into account all possible growths: chain and roller?

 

Also, doesnt measuring chain growth over non-full lengths assume all chain links and rollers wear approximately the same? So the weakest links which contribute the max percentage of length might be missed giving a false negative?

[Minion]

 

if measuring over a limited length of chain realizes errors of various values depending onthe measured length' date=' isn't the best option to measure the whole chain as that will take into account all possible growths: chain and roller?[/quote']

This would be the most accurate way to do it. There are two problems that make it less convenient.

1.) You have to take it off the bike to measure it.

2.) A full chain is around 1300mm (53") long. It's hard to find a straight edge that long so you're left trying to align a flexible tape measure next to a flexible chain.

 

12" works nicely because the maths is convenient: 1% ~= 1/8", there is just over 12" of free chain length that you can easily measure while it's mounted on the bike and 12" straight edges are fairly easy to come by while being less cumbersome than 18" or 24" ones.

 

Also' date=' doesnt measuring chain growth over non-full lengths assume

all chain links and rollers wear approximately the same? So the weakest

links which contribute the max percentage of length might be missed

giving a false negative?[/quote']

It does make this assumption. I think, however, it is a pretty accurate assumption whose benefit of easier measurement far exceeds that (rare) cost of uneven link wear.

 

[Johan Bornman]

if measuring over a limited length of chain realizes errors of various values depending onthe measured length' date=' isn't the best option to measure the whole chain as that will take into account all possible growths: chain and roller?

Also, doesnt measuring chain growth over non-full lengths assume all chain links and rollers wear approximately the same? So the weakest links which contribute the max percentage of length might be missed giving a false negative?

[/quote']

 

Edman's answer is elegant and should answer your questions. However, I want to add that by measuring the sideplates, rollers are completely ignored, as they should. If you rely on roller measurements, you have to ensure that the chain is perfectly clean each time you measure, since dirt inside the rollers is what gives you the variable measurement. Dirty, one length, clean, another length.

 

We know dirt to have an effect on how chain components compress since most of the quick link designs from Sram, YBC, KMC etc are all released by both squeezing the two plates together and simultaneously moving the two plates away from each other. On a dirty chain it is very difficult to release these links since they cannot compress.

 

 

[Guest Big H]

if measuring over a limited length of chain realizes errors of various values depending onthe measured length' date=' isn't the best option to measure the whole chain as that will take into account all possible growths: chain and roller?[/quote']
This would be the most accurate way to do it. There are two problems that make it less convenient.
1.) You have to take it off the bike to measure it.
2.) A full chain is around 1300mm (53") long. It's hard to find a straight edge that long so you're left trying to align a flexible tape measure next to a flexible chain.

12" works nicely because the maths is convenient: 1% ~= 1/8", there is just over 12" of free chain length that you can easily measure while it's mounted on the bike and 12" straight edges are fairly easy to come by while being less cumbersome than 18" or 24" ones.

Also' date=' doesnt measuring chain growth over non-full lengths assume all chain links and rollers wear approximately the same? So the weakest links which contribute the max percentage of length might be missed giving a false negative?[/quote']
It does make this assumption. I think, however, it is a pretty accurate assumption whose benefit of easier measurement far exceeds that (rare) cost of uneven link wear.

 

Surely the purpose of any test is to take samples..... you never ever will measure the chain once and say .... aha .... my chein are gud.... duh!!!!!!! Measure the damn chain a FEW times ... at random ..... if you are statisticaly minded and evaluate the results..... capice!!!!!!!

[Capricorn]

 

 

its capisce?

but i was just checking my logic against that of the bigwigs. Very well aware of representative sampling that takes its justification from stats. Even lazyness has a basis..?

But thanks for the feedback.

 

Capricorn2009-08-09 07:44:22

[Tumbleweed]

good question. johan' date=' i would like to see pics of the park tool measurements against those of the ruler. any chance?[/quote']

 

I am sure you would like to see it. Why not just do it yourself?   

 

Interesting to see that a Hubber called "roller" does not trust a ruler...... neither do I trust the part of his name that is "holy"!!!!!!!!!!!!

if that's interesting you must be very bored in angola. look up the two words together, and ignore results that carry the word maxxis...btw, i love this line from the doccie that is being gooi-ed: "Using a ruler can be error-prone..." holy roller2009-08-09 21:13:20

[saartjie]

Johan

 

I just press the tip of my steel ruler, that start at zero, against the pin.  Why would you want to "modify" a ruler?

 

 

[Johan Bornman]

Johan

 

I just press the tip of my steel ruler' date=' that start at zero, against the pin.  Why would you want to "modify" a ruler?

 

 

[/quote']

 

Mej Baartman

 

'cause this is a special ruler that doesn't start at zero like steel rulers.

 

It has a blank lead-in that's not graduated. If I saw off the lead-in, then I lose the spoke measurement capabilities. If I use a standard steel ruler, I have to find one that goes up to 13 inches. Pretty scarce.

 

 

[scuzzy]

Just saw the video on chain measuring, basically show what Johan is advising us here,  I need to go and look for a steel ruler now, just one question though, how many millimeter in 12 1/16 inche, trying to work it out but I'm not sure, can anybody help with this conversion please.

 

Thanks

 

[Matchstix]

1 inch = 2.54 cm if that helps

[dollar]

306.32?

[AndreZA]

Scuzzy, don't look for a one with mm and then convert inches to mm. Look at art stored for the rulers. If they are made in the US or for a US company the chances that they are in inches are quite good.

[Dirtbreath]

Makro!