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Sofa King We Todd Did
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When I first put this bike together, the chain was incredibly taut. Tighter than a duck's butt. But not too tight that I'd break the 15 year-old chain on a mash. It was perfectly straight across the top, and perfectly straight across the bottom. Now I've probably tucked about a 80 miles or so of road riding with this sucker and I've noticed that the tightness is all but gone. The chain's not slack by any means. It's probably just the right length tight now. Still no need for tensioner so that's frickin' ace.

Until now, I thought that stretched chains was something of a myth. Maybe not a myth, but maybe something that's picked out by only the most eagle-eyed rider. And one who mashes the hell out of his ride. I had visions of these people continually pounding uphill for miles on end, every single day. That was who I thought stretched chains were reserved for. I certainly didn't think that a big gear matched with some modest road riding could stretch out a chain this easily...!
 

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nachos rule!
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390 Posts
actually, chain stretch is a complete misnomer. what you're seeing is the effect of ovalization of the holes in the side plates, and to a lesser extent pivot pin and bushing wear. a slight bit of wear at every pivot point, times two pivots per full link, adds up to a noticable lengthening of the chain over time.
 

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(was) Big in Japan
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supercorsa said:
actually, chain stretch is a complete misnomer. what you're seeing is the effect of ovalization of the holes in the side plates, and to a lesser extent pivot pin and bushing wear. a slight bit of wear at every pivot point, times two pivots per full link, adds up to a noticable lengthening of the chain over time.
Or maybe it is the teeth on the ring and cog wearing a little. If you use a cheap stamped cog like a Novatec or Shimano DX the faces of the teeth that contact the chain under load are far from perfect. They always seem to have a ridge on them, or a burr from the stamping process. I've noticed that my chain "stretched" as I wore these down, then once they had been worn flat (and thus the roller of the chain contacted the whole width of the teeth) the wear and stretching died away to an almost imperceptible rate.

I recommend taking a look at that cog of yours...you might be able to see what I'm talking about. I don't have any photos of that sorry.
 

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Stretch?

That's minimal stretch. If you measure the chain before and after it's only ~1/32" inch longer than it was when it was tight - eyeballing a 1/2" total sag (a 1/4" sag means the chain stretched 0.008". :eek: )
 
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