Originally Posted by
habilis
Interesting that you work with percent of length as a measure of stretch, or did you mean .5 mm?
I meant percent, making it easy to compare to other units of measure and distances measured.
Originally Posted by
habilis
Most people use inches, and discard a chain when it stretches beyond 1/16 inch over a 12" span.
1/(16*12) = 1/192 = slightly more than .5%.
Originally Posted by
habilis
So you use the "inside" caliper jaws to pull the rollers apart?
Yes. Otherwise I'd have to apply pressure.
Originally Posted by
habilis
Good thought, but with the right pedal at 3 o'clock and a sneaker hanging off it, you have a straight-enough chain.
Is that really enough tension? We use chains under pretty high tension. I still have to hold it still.
Originally Posted by
habilis
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.
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.
Originally Posted by
habilis
Your method seems to be drawing you into issues, like pin diameter, which are irrelevant if you measure a larger number of links.
They're irrelevant even in my case. I asked before I thought about it thoroughly.
Originally Posted by
fietsbob
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.
What with a 52 chainring and a 34 cog I don't shorten my chains.
Originally Posted by
fietsbob
LBS has a bin full of old Chains to sample More ..
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.