Workshop tales, trials and disasters.
Maintenance tips, techniques and myths.
Technical discussion, description and outright lies
8 posts • Page 1 of 1
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?
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.
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.
Since I keep misplacing my common sense down the shed, I guess I'll have to borrow someone elses off the internet.
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.
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
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)!
8 posts • Page 1 of 1
Who is online
Users browsing this forum: No registered users