Bike Forums - Ruler and Chain Checker are Diverging

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- - Ruler and Chain Checker are Diverging (https://www.bikeforums.net/bicycle-mechanics/1268719-ruler-chain-checker-diverging.html)

Quote:

Originally Posted by cyccommute (Post 22836449)

At the risk of waking the sleeping dog, I measured the chains again with my Pedro chain checker that isolates the rollers. I measured them against the Park chain checker. The first set of pictures is for a new chain. No difference in the measurement.

https://cimg8.ibsrv.net/gimg/bikefor...8b2d8870d.jpeg
https://cimg5.ibsrv.net/gimg/bikefor...5457b5f87.jpeg

Then a chain that measures less than 0.5% with the Park Tool. Again, no difference. Pedros says it is good

https://cimg0.ibsrv.net/gimg/bikefor...c476d895f.jpeg

For a chain that is over 0.5%, the Pedros would probably fail it. Not a big deal actually. You might loose 200 miles.

https://cimg3.ibsrv.net/gimg/bikefor...e76066970.jpeg
https://cimg3.ibsrv.net/gimg/bikefor...853a7b8e6.jpeg

The chain that has greater than 0.75% fails with both.

https://cimg7.ibsrv.net/gimg/bikefor...4e6121aa5.jpeg
https://cimg0.ibsrv.net/gimg/bikefor...d6c659817.jpeg

Isolating the rollers makes no real difference.

Just for giggles, I also measured the shoulder on the inside of the inner plate that the roller rolls on. It measured out to 5.3mm on the chain that indicated 0.75% wear. It measured the same 5.3mm on the chain with less than 0.5%. While I was measuring, I measured just the outer edge of the roller on the same two chains. I tried to get as far out on the roller as I could and it was the same thickness as I previously measured. There is no roller wear that I could measure and certainly not enough of a difference in any part of the chain that could explain chain wear except for the changes in the pin diameter.

You know you have to tension between 1 and 2 on the Pedros and similar to get a useful measurement, right?

Quote:

Originally Posted by Kontact (Post 22836528)

You know you have to tension between 1 and 2 on the Pedros and similar to get a useful measurement, right?

Yes and I did. No difference. It is hard to hold in place while taking photos. Both checkers gave the same measurement.

Honestly. That Vernier looks like garbage and its half silly to believe some wear point doesn't wear while others do. Wear on the inside of the rollers, that you claim isnt there, is even visible in you own picture. Compare a new one to an old one by eye and you'll see.

Just to be clear, the holes in the inner plate gets bigger, the diameter of the roller land on the inner plate gets smaller, the diameter of the pins get smaller, the hole in the rollers get bigger and the OD gets smaller. This is all easily measured with a shop quality digital calliper.

Some of these contribute to actual chain elongation, the others only to slop in the rollers that may lead to false conclusions, unless accounted for. The park tool may have some compensation for roller wear built in, to get the same results as the Pedros, I dunno, but Id like for someone to measure the actual length of that tool to see what Park considers +0.5% etc.