Workshop tales, trials and disasters. Maintenance tips, techniques and myths. Technical discussion, description and outright lies
by Jean » Fri May 23, 2008 2:50 pm
Hi,
Just wondering how a 25.8mm set of drop bars (which is a common Italian sizing) goes getting into a 26mm A-head stem?
I gather 25.8mm was established as in-between size in the 'old days' which could be used with either 26mm stems or a smaller '25.?' stem. I suppose that worked fine in the days of quill stems with their wrap around style bar clamp, but does it still work with A-head style stems which have the bolt on face plate?
Cheers
Jean
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Jean
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by BNA » Fri May 23, 2008 4:02 pm
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BNA
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by rustychisel » Fri May 23, 2008 4:02 pm
I would try it, if it clamped I'd ride it. (alloy bars and stem, I'm assuming). Problems happen with 25.8mm bars and 26.4mm stems, which need to be shimmed (usually 1 1/2 rounds of a beer can shim). Manufacturing tolerances can be in the order of 0.2mm easily, as it happens.
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by Jean » Fri May 23, 2008 4:26 pm
Alloy stem definitely, alloy bars probably.
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Jean
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by HappyHumber » Fri May 23, 2008 4:43 pm
Cut up a coke can, or similar, and wrap it around the bars at the mount point to give you that extra mm or so's worth of thickness - voila - a simple shim.
I got in just before the Alco-pops TAX and bought a six can pack of Scotch & Dry to get my 25.8 seat post in a 26.0 seat tube. 
Kym All manner of half finished projects and a bit of randonneuring I used to be tech-savvy. Now I'm just tech-weary.
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by Jean » Fri May 23, 2008 4:49 pm
HappyHumber wrote:Cut up a coke can, or similar, and wrap it around the bars at the mount point to give you that extra mm or so's worth of thickness - voila - a simple shim. I got in just before the Alco-pops TAX and bought a six can pack of Scotch & Dry to get my 25.8 seat post in a 26.0 seat tube. 
A shim is always an option, but the purist in me is trying to avoid it. This is not an immediate problem but I'm just thinking through my options for a build I'm planning for later this year or early next.
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Jean
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by LuckyPierre » Fri May 23, 2008 5:26 pm
I think that 25.8mm bars should be OK in a 26mm head stem.
Let me know the easiest way for us to catch up and you can borrow one to see how it goes.
Litespeed Classic - 3Al/2.5V titanium tube set, Record 9-speed groupset, Open Corsa Evo CX Alchemy Diablo - Columbus Zonal tubing, Ultegra 9-speed groupset, UltraGatorskins Gitane Rocks T1 - U6 tubing, Deore/XT groupset, CrossMarks
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by Jean » Sun May 25, 2008 1:35 pm
Thanks for the offer. The 25.8mm bar in question is presently on my bike so it's not really free for fitting trials at the moment, but when the time comes I may take you up on it.
The build, when it happens, will require a silver polished stem (as opposed to the stock standard of these days - black  ) and the only ones I can find are 26.0mm clamp, but lots of the sorts of bars I'd like are 25.8mm. Now if I could just find a good silver alloy bar (outside of Ebay)!
Cheers
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Jean
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by LittleWheelsandBig » Sun May 25, 2008 10:24 pm
25.8 and 26.0 handlebars and stems are functionally interchangeable.
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