I measure chains with a 6-inch digital caliper; it reads to .01mm (accurate to .03). I measure 5.5 links because one jaw is too thick to fit between the narrower set of pins, 6.5 links is too long for the caliper. I measure different model chains as having different lengths new, as much as 1.5 mm out of 145. Do they have pins that are different thickness or have I mismeasured?

I thought for another minute and realized I'm not measuring the thickness of 12 pins, but only 2, unlikely to vary in thickness by as much as I measure.

I think "length " and "diameter" are more clear terms for pins.

A better way to measure is with a 12" ruler. Your method of measure is less precise because "stretch" will be more evident over a longer distance.

I have a good-quality metal ruler. I have a hard time measuring chain stretch with the necessary precision (I discard at .5% stretch.) when mounted. And I have no chance of measuring it to ,03mm precision. The extra precision of the digital caliper makes it superior. Plus it applies stretch itself as well as anchors itself between the points it measures. But, obviously, I have been careless about placing its jaws in the same place on the pins.

i have a sneaking suspicion that measuring chain lengths is primarily a preoccupation WRT males...

Interesting that you work with percent of length as a measure of stretch, or did you mean .5 mm?
Most people use inches, and discard a chain when it stretches beyond 1/16 inch over a 12" span.

So you use the "inside" caliper jaws to pull the rollers apart? Good thought, but with the right pedal at 3 o'clock and a sneaker hanging off it, you have a straight-enough chain.

I prefer the ruler because it measures a larger sample of the chain and shows stretch as a percentage of 12 inches rather than of just a few links. Your method seems to be drawing you into issues, like pin diameter, which are irrelevant if you measure a larger number of links.

Learn ByMeasuring.

Your Measurement Protocol may need work..

you can use the extra piece of chain remaining from when you shortened a chain to fit,
and press out a Pin and measure it with your Digital caliper .

LBS has a bin full of old Chains to sample More ..

I meant percent, making it easy to compare to other units of measure and distances measured.

1/(16*12) = 1/192 = slightly more than .5%.

Yes. Otherwise I'd have to apply pressure.

Is that really enough tension? We use chains under pretty high tension. I still have to hold it still.

I measure 46% as many links but with 20 times the precision (if the ruler is marked in 32nds). I don't need that much precision but it's better than measuring 12 inches to a 32nd.

They're irrelevant even in my case. I asked before I thought about it thoroughly.

What with a 52 chainring and a 34 cog I don't shorten my chains.

After many years of living in the boonies I developed the habit of doing all my own work - even rebrazed the seat tube back in the bottom bracket once. I won't annoy the poor folks at the LBS by rooting around in their old chain bucket.

My old chains pins are worn; the new chain is just 1 data point. I asked in case this was an issue people had paid attention to and knew off-hand.

What Wears in derailleur chains is the inner link plates which have been punch forged to form less than half the width of the Roller .

the roller edges contact that and the inner surface of that partial Bushing will wear itself and the Pins ..

I suspect the Pins and rollers Are tempered differently than the chain link plates ..


The Pitch of all Bicycle Chains is 1/2" , 0.50" that is a standard ..

You want to Know the thickness of the Chains individual Centre pin it self ? remove one and measure it.

Wear per link may be to the 4th decimal Point (0.0001), but it all adds Up.

Bicycle chains started out as ANSI #40 chains and have been modified over the years. The ANSI spec for pin diameter is 5/32" and roller diameter is 5/16".

It appears you are measuring inside the chain - the rollers. That is not the same as measuring the distance between rivets (pins). There are likely different thicknesses of rollers that would explain the different measurements for different brands of chain. By measuring between opposite sides of the rollers you are measuring roller wear as well. See this for an explanation of how to measure via the rollers - not possible with your calipers. chain wear indicator- Mtbr.com

More precision seldom causes problems, while too little precision can often cause problems. Keep doing what works for you.

It appears you are measuring inside the chain - the rollers. That is not the same as measuring the distance between rivets (pins). There are likely different thicknesses of rollers that would explain the different measurements for different brands of chain. By measuring between opposite sides of the rollers you are measuring roller wear as well. See chain wear indicator- Mtbr.com for an explanation of how to measure via the rollers - not possible with calipers.