Duragrouch

OK, in opposition to my own stated logic, thinking real hard about this, I may see a possibility of non-exact-digital tooth-for-tooth rotation. Or I could be wrong. Follow me here... Let's start with the chain, and you have a chain that is greatly "stretched", meaning a lot of wear at the pins and inner plates, so that the distance over 8 links is slightly more than it should be; It's wrapped about 180 degrees around the rear (16 tooth) cog; The link on top is fully engaged with the tooth it is pulling on; Each subsequent trailing link is incrementally a bit looser, has the tiniest gap between the roller and the tooth in front of it; So as the chain advances under drive torque, by the time the 8th link passes off the last tooth on top, if staying fully under drive torque (tension in chain, resistance to rolling by the wheel), by the 8th link, the cog is very slightly lagging in rotation, and with each subsequent link, you get cumulative error. Hmm... I'm not certain about the above, but thinking about it. And I can see the same source of variation being due to varation in the cog. So I think it depends on the relationship between the two, and the key being, how much rotation of the cog for each linear passage of the chain, under drive load? If each chain roller passing over the chain is perfectly centered in the valley between teeth, I think you get no variation in rotation, because the angular movement is perfectly synched. But, if that is not the case, the top link pushing on the tooth in front of it, and chain or cog relationship such that each following link having an increasing gap in front of it until its tooth reaches the top, under constant drive load, then I could see having less rotation per given chain passage, assuming that is constant, driven by crank rotation. For the above to happen, there must be looseness, i.e., variation in pitch, between chain and cog. I could be wrong. I'm just trying to offer the chance that I was wrong previously.

Discuss.