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Potential bad idea? 26.4 bars, 26.0 shim, 31.8 stem

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Potential bad idea? 26.4 bars, 26.0 shim, 31.8 stem

Old 07-28-12, 09:03 PM
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Potential bad idea? 26.4 bars, 26.0 shim, 31.8 stem

I have a pair of older cinelli bars with the old cinelli 26.4mm clamp standard that I would really like to run with a modern stem. I want to use them with a legitimate sized shim but apparently, 26.4->31.8 shims are a rarity. I do alternatively have a 26.0->31.8mm shim which I could use going out on an arm and a leg. The stem is open faced with a 4 bolt design. I'm running this through you guys for input/ insight. Would this be a potential bad idea in the making?
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Old 07-28-12, 09:05 PM
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Piece of alu from your favorite beverage could do the trick.
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Old 07-28-12, 09:13 PM
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Originally Posted by zonatandem
Piece of alu from your favorite beverage could do the trick.
Any ideas of the number of wraps I should do? I'm working with a 31.8mm clamp stem as stated above.
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Old 07-28-12, 09:15 PM
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Originally Posted by zonatandem
Piece of alu from your favorite beverage could do the trick.
Why do people assume that a soda can's wall thickness would magically be the exact amount needed to shim any and all bars or seatposts.

26.4-31.8 = 5.4mm is a sizable difference, (2.7mm/side) far more that typical than typical soda can thickness.

To the OP----Unfortunately the extra .2mm/side of the wrong shim can be an issue. The curvatures of the stem and clamp are pretty precise, and an oversized bar (including shim) can introduce enough local stress to cause premature clamp failure.

Either source the right shim, or if you have an adjustable reamer, ream the extra .4mm out of the ID of your shim. If you can't get the right shim and you or the local shop have a reamer, post that & I'll tell you how to do the job.
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Old 07-28-12, 09:21 PM
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I'd only consider this with flat bars.
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