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Discussion Starter · #1 ·
New to cycling and I don't have any Park tools and I want to see if my 9 speed chain is still within tolerance to keep it on the bike. As I said I don't have any Park tools but I do have a dial caliper to measure between links. What I don't have is what should a new chain measure between rollers? Is there a standard measurement that has been defined by the bike industry as to what a new 9 speed chain measures between rollers? If so what and where is it.
 

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Discussion Starter · #3 ·
Thank you for that. I like tools and all but if I have something at home already that will do the same thing then why buy a specialty tool to do it.

Thanks again
 

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Discussion Starter · #4 ·
I've been taking some measurements from this website http://www.sutherlandsbicycle.com/Chapter5.pdf and Mike T's chain measurement site Chains and have found that a chain roller diameter is 7.7216 mm on a new chain and the distance between rollers is 4.9784 mm on a new chain. I want to use a dial caliper (because it's only a 6" caliper) to measure the distance from roller to roller instead of a tape measure so I came up with a formula.

Measured in Millimeters

n=number of rollers wanting to measure

(7.7216 x n) + ((n-1) x 4.9784)) = Outside distance (OD) between the number of rollers chosen.

So with that I know per Mike T's site that if a chain is 1/16th past the 12" measurement or .5% then it's near it's time for replacement. So I need to take the above equation outcome x .5% to get the near time replacement of a chain.

*Note: Since I'll be using a 6" caliper I take a few random measurements to come up with a good sample to make a determination if the chain is within specs.


Anyway check my math guys and see if that formula will work.
 

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Thank you for that. I like tools and all but if I have something at home already that will do the same thing then why buy a specialty tool to do it.
Thanks again
A measuring tape is, of course, a tool. The good thing about a 12" tape, or ruler, is that it magnifies the distance measured by the tools that have been made for the job - those being approx 4" long. To go one step further I have a 4 foot tape hanging from my basement ceiling joist with a nail very carefully placed alongside it. So now I have a measuring device that amplifies the wear 4x more than a 12" tape. Of course the 12" version can be used with the chain still on the bike so it's much more useful - and proven over many decades to be quite efficient.
 

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A bike chain is based on English inch measurements. The chain pitch (distance between the pins) is .500 inch. This dimension must be very accurate and the same between brands, but if you measure between the rollers, using the internal tips of calipers, you'll find substantial differences between brands. A Campy chain may measure 5.200 inches when new, but Shimano or KMC chains can measure 5.210-5.215 inches, due to differences in the roller OD, ID and the OD of the bushing formed into the inner side plates.

If this measurement is used to evaluate chain wear, you're mixing both the change in pitch with roller wear. When the true elongation of a chain (measured properly between the pin centerlines) reaches .5%, the wear between any two rollers can be as great as the elongation, measured over such a short length. Your caliper reading may suggest an elongation of 1%, when it's only .5%. This is why most chain checkers are so inaccurate. They may show a new Campy chain to have zero wear, but a new Shimano or KMC chain to be worn by .25%. Future reading will add both this false wear and roller wear to the true elongation.

Different chain brans also wear differently. Campy chain may have .15% elongation after 6,000 miles of use, but the rollers will be extremely worn at that point, with a space between the rollers of .240 inch (compared to .200 when new). The chain should have been tossed before that mileage was reached. A Shimano or KMC chain is likely to reach .5% elongation after only 3-4,000 miles, but roller wear at a given mileage may be similar to a Campy chain.
 

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Discussion Starter · #10 ·
A bike chain is based on English inch measurements. The chain pitch (distance between the pins) is .500 inch. This dimension must be very accurate and the same between brands, but if you measure between the rollers, using the internal tips of calipers, you'll find substantial differences between brands. A Campy chain may measure 5.200 inches when new, but Shimano or KMC chains can measure 5.210-5.215 inches, due to differences in the roller OD, ID and the OD of the bushing formed into the inner side plates.

If this measurement is used to evaluate chain wear, you're mixing both the change in pitch with roller wear. When the true elongation of a chain (measured properly between the pin centerlines) reaches .5%, the wear between any two rollers can be as great as the elongation, measured over such a short length. Your caliper reading may suggest an elongation of 1%, when it's only .5%. This is why most chain checkers are so inaccurate. They may show a new Campy chain to have zero wear, but a new Shimano or KMC chain to be worn by .25%. Future reading will add both this false wear and roller wear to the true elongation.

Different chain brans also wear differently. Campy chain may have .15% elongation after 6,000 miles of use, but the rollers will be extremely worn at that point, with a space between the rollers of .240 inch (compared to .200 when new). The chain should have been tossed before that mileage was reached. A Shimano or KMC chain is likely to reach .5% elongation after only 3-4,000 miles, but roller wear at a given mileage may be similar to a Campy chain.
After reading this I have one thing I'm going to do. The next time I buy a new chain I'm going to measure pin to pin on a 12" scale in a few places to get a good base line measurement.

Also after reading this I have a question. With the "bushingless" chains that most of us have does the pin wear proportionate to the roller wear?
 

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After reading this I have one thing I'm going to do. The next time I buy a new chain I'm going to measure pin to pin on a 12" scale in a few places to get a good base line measurement.

Also after reading this I have a question. With the "bushingless" chains that most of us have does the pin wear proportionate to the roller wear?
Part one: you say you read this but clearly you didn't comprehend it. A new chain will measure exactly 12 inches for 24 links pin to pin. You won't be getting a base line by taking several measurements: you'll just get the same number over and over and it will be 12.0 inches.

Part two: wouldn't the relative relationship of pin wear to bushing wear be pretty dependent on the materials used for those differen parts in different chains? IOW wouldn't it make sense that it would be different from one brand/model of chain to another?

You should read and comprehend c-40's post.
 

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After reading this I have one thing I'm going to do. The next time I buy a new chain I'm going to measure pin to pin on a 12" scale in a few places to get a good base line measurement.

Also after reading this I have a question. With the "bushingless" chains that most of us have does the pin wear proportionate to the roller wear?
At .5% elongation, you have, the combined wear on each pin and bushing pair averages .0025 inch. The wear on the rollers will be much larger. If the space between the rollers increases by .040 inch, then you have .020 for each roller, but that's a combination of wear on the roller OD, ID and the bushing formed into the inner side plate. I've measured roller ODs that were about .005 inch smaller at that point, with the wear on the ID being much greater.

A good tool to use for measuring elongation is a 12" machinist's rule, like this:

General Tools 1216 12-Inch Flex Stainless Steel Rule - Amazon.com

Place one end on the edge of a pin. The pin at the opposite end will be completely covered, when the chain is new. When that pin is exposed by nearly half it's diameter, you're at .5% elongation. I never managed to get even close to .5% elongation with a Campy chain, before the roller were shot and the side clearance was about twice that of a new chain.

When I got serious about chain elongation measuring, I made my own full length gage with a tight fitting pin at one end and a machinist's ruler located with it's center, precisely 53 inches from the center of the pin. Place the inner plate end of the chain over the pin, the stretch the chain out with a moderate tension and measure the elongation with the ruler at the opposite end. You'll find most new chains to be a little short of a whole inch number, but it probably only takes a ride or two correct that.
 

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Discussion Starter · #13 ·
Yes Iron I get your point the chain will measure 12" pin to pin every 24 links. I didn't before but now I do. Measuring chain wear points whether it's elongation or roller wear helps me recognize when a chain needs to be replaced. In return my components will lasting longer. I enjoy maintenance on machinery and enjoy keeping them in tip top shape. Learning by asking questions is the reason for this post
 

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Discussion Starter · #14 ·
I never managed to get even close to .5% elongation with a Campy chain, before the roller were shot and the side clearance was about twice that of a new chain.
With this statement it makes my attention to measuring roller wear seem plausible in my #4 post.
 

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With this statement it makes my attention to measuring roller wear seem plausible in my #4 post.
Yes, it makes sense with any chain that exhibits this wear pattern. If you want to get the most mileage from a cassette, alternate the use of 3-4 chains and change to a new one when the space between rollers increase by 015-.020 inch. If you get some use on all of the chains and never encounter new-chain skip, you can then alternate more frequently, like whenever a chain is removed for cleaning and you'll never get new-chain skip. I'd still toss a chain when the space between rollers increases by .035-.040. When the last chain in the group has this much wear, you toss the cassette and start the whole procedure over with a new cassette and new chains.
 

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Discussion Starter · #16 ·
Yes, it makes sense with any chain that exhibits this wear pattern. If you want to get the most mileage from a cassette, alternate the use of 3-4 chains and change to a new one when the space between rollers increase by 015-.020 inch. If you get some use on all of the chains and never encounter new-chain skip, you can then alternate more frequently, like whenever a chain is removed for cleaning and you'll never get new-chain skip. I'd still toss a chain when the space between rollers increases by .035-.040. When the last chain in the group has this much wear, you toss the cassette and start the whole procedure over with a new cassette and new chains.
That sound like a good plan
 

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Yes Iron I get your point the chain will measure 12" pin to pin every 24 links. I didn't before but now I do. Measuring chain wear points whether it's elongation or roller wear helps me recognize when a chain needs to be replaced. In return my components will lasting longer. I enjoy maintenance on machinery and enjoy keeping them in tip top shape. Learning by asking questions is the reason for this post
While I can't claim to take the kind of measurements to which you refer, I consistently get 9,000+ miles from a Campy chain where it hits 0.5% elongation. I have to replace the cassette after the 2nd chain has worn out. I ride mostly on flat roads and in a 53/19 much of the time so the chain is in about as low a stress situation as possible plus it gets properly maintained. I experience minimal shifting issues even when the chain is near the end of its life. YMMV
 
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