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Bicycle chain too short

Old 05-25-14, 09:13 AM
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JT101
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Bicycle chain too short

I have noticed a strange thing about my chain.

I noticed the gears were not smooth so I went to check the length of the chain. I counted 12 rivets which measures 1/4" less than 12 inches.

So I checked on my other bikes. One other measures similar, and the one with a brand new chain measures 1/2" shorter. I checked it several times.

I remember in the past checking a new chain and it reading exactly 12 inches. Obviously, normally you'd expect a worn chain to be longer, not shorter.

I think I may have something wrong her. I'm just using a stainless steel ruler to measure like I've always done

Thanks
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Old 05-25-14, 09:16 AM
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RubeRad
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I think you must be miscounting
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Old 05-25-14, 09:34 AM
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Wilfred Laurier
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if you are measuring from centre of link to centre of link correctly
then the ones that seem 1/4 too short
are actually 1/4" stretched
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Old 05-25-14, 10:09 AM
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JT101
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Originally Posted by RubeRad View Post
I think you must be miscounting
I think you were right. I counted the number of outer plates within the 12 inches, but of course it's one set of outers and one set of inners, so it's well over stretched at 1/4"

Thanks

off to buy a new chain and sprockets
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Old 05-25-14, 10:17 AM
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However, I just realised that one of the chains is less than 6 months old (the one that has stretch 1/4"). I do hammer my bike on a daily commute through the streets of london, and I don't do enough maintenance on it, but we're talking 7 miles round trip, and only small journeys on weekends. So we're talking in the region of 840 miles. That's a Shimano 7 speed chain. Does that sound normal.
Just reading online, that sand and oil make a great grinding paste to wear chains. I work on a building site, and it get's covered in sand and dust all the time, so that might explain it.

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Old 05-25-14, 11:21 AM
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Originally Posted by RubeRad View Post
I think you must be miscounting
+1 Odds are he's counting the first rivet, and not counting from the first rivet.

It's like footprints in the sand. If you take 10 steps, you'll leave 11 prints. The one you started from plus 1 per step.

So 12" of chain would likewise include 24 links & 25 rivets.
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