Originally Posted by
eddy m
Wrong again. In a modern derailer chain, the wear occurs between the pin and the inner side plates, which are shaped to bear against the pin on the inside of the hole and to bear against the roller on the outside of the hole. the roller moves around and wear on it doesn't cause much trouble. Chain "stretch" is really wear between the pin and the inner side plates. That wear is concentrated in a range of about 30 degrees on the pin and the corresponding surface of the plate. That leaves about 330 degrees of unworn surface in even the worst chain. If you turn it over, you can move the load to the clean part of the surface.
So if the pin only wears while it travels around the cassette and through the pulleys, and the wear is in a narrow section of the pin, and when a link is traveling either to the rr der or away from the rr der, there is low stress and therefore low wear, then the only time the wear in the pin becomes a factor is when it passes over the cassette and through the pulleys?
So you are saying that the effective length of each link changes at this critical point and that once clear of the cassette and pulleys, it returns to normal length because the worn part of the pin is no longer bearing the load? A different section of the pin is?
If this is true, I should be able to measure a difference between the center of the pins when a link is bent under load and when it is straight and under less load?
This sounds like a job for DIGITAL MIC!