26.0mm bars in a 25.4mm stem?

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Cliff
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26.0mm bars in a 25.4mm stem?

Postby Cliff » 20 Jan 2009, 11:55am

I need a new stem and and considering an adjustible one, for which the common sizes are 25.4mm and 31.8mm. My bars are 26.0mm. So the bars will go in with a bit of deformation. Of course you then cause a stress concentration at the bend and partically work harden the material.

But the question is can the bars cope, or does this deformation lead to failures? 0.6mm doesn't sound like much, really.

Has anyone used this combo?

Tonyf33
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Postby Tonyf33 » 23 Jan 2009, 1:37am

Never tried it but are the bars steel or alloy? Maybe possible but still a bit dodgy with a set of steel bars but with alloy bars it sounds like an accident waiting to happen. you didn't say wether it was ahead stem or quill. A ritchey one here from Je James with free delivery for £22(check with them to make sure it is the road version but it looks like it)
http://www.jejamescycles.co.uk/id42678.html
In any case why not get a stem with the angle you require? I always found adjustable stems creaky & fidgety with slight movement no matter how much you tightened them.

rogerzilla
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Postby rogerzilla » 23 Jan 2009, 6:53am

If the stem has a removable faceplate (like all modern A-head stems) it is generally OK. Tolerances vary - I have some 25.4 bars in a (conventional) 26.0 quill stem, and bought the proper shims to fill the gap - only one of the two halves of the shim can actually be fitted, so the hole in the stem is more like 25.7mm.

willem jongman
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Postby willem jongman » 23 Jan 2009, 9:18am

I don't think this is a smart plan. and for two reasons. First, this is precisely how and where bars sometimes fail, and you really don't want to experience that. Second, I don't like adjustable stems: they are heavier, more expensive, not as stiff, and less reliable. Just find out what size you need, and get a fixed stem. For threaded steerers Nitto do really tall ones in many sizes.
Willem

bailout
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Joined: 9 Jul 2008, 2:46pm

Postby bailout » 23 Jan 2009, 12:56pm

I was looking into the same question. I have a bike with drop bars that I don't find very comfortable and am thinking of putting an adjustable stem on so I can try different positions.

Have you checked the diameter of your bar? According to my measurements my bar is actually 25.6 or 25.7 so there is probably some variation in actual diameter from the stated. According to Sheldon most road bars are 25.4 so don't assume, like I did, that road bars are all 26 and mtb are 25.4. As far as I can see from google the stem that is on my bike now is only available in 25.4.

willem jongman
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Postby willem jongman » 23 Jan 2009, 1:08pm

Most nice road bars are 26.0 (or 31.8 for oversize mostly carbon), and some are 25.4. also, there are some (not many) that are 25.8. If you are not comfortable with your bar, it may be too low. On a touring bike, I like my drop bar to be about level with the saddle, or a bit above that. If you have a threaded steerer, you can try to raise the bar. On a threadless steerer, this is a more complex operation requiring a slightly longer and seriously upward sloping stem. Some drop handle bars are too uncomfortable for touring. Many find the Nitto noodle bar the most comfortable bar. I love mine (in 46 cm).
Willem

daveray
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Postby daveray » 23 Jan 2009, 4:22pm

There is an adjustable stem for 26mm bars - the Look ergostem. It comes in Ahead only nowadays but quill ones do come up on ebay. They are far superior to normal hybrid type adj stems as they are, I believe, designed with track and time trials in mind.
Image

willem jongman
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Postby willem jongman » 23 Jan 2009, 4:28pm

Yes, but they were very very expensive. Thinking hard about what you want would be a far cheaper alternative.
Willem

bailout
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Joined: 9 Jul 2008, 2:46pm

Postby bailout » 23 Jan 2009, 10:26pm

daveray wrote:Image


Would be great to borrow or hire one to work out the best position and then buy a solid and cheaper stem to that fit.

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andrew_s
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Location: Gloucestershire

Postby andrew_s » 23 Jan 2009, 11:26pm

Ergostems are sometimes a club purchase, so members can decide on the right position without having to try lots of stems on a trial and error basis.

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For 26mm bars in a 25.4 stem, there's also the possibility of the stem faceplate cracking in the middle, as well as of bar failure. It did happen to me one time, though I think the bars were the right size.

JohnW
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Location: Yorkshire

Postby JohnW » 24 Jan 2009, 12:32pm

I have 25.4 bars in a 26.00 stem, packed out (sorry - shimmed) with a bit of aluminium sheet taken from a Chinese Take-Away type tray - from M&S actually (this isn't just Chinese Take-Away tray, this is M&S Chinese Take-Away tray).

This works fine, but personally, I wouldn't open a traditional quill stem out from 25.4 to 26 - stresses have been referred to above, and I think that it would apply stresses were they weren't designed for - and when a stem snaps, it snaps spectacularly.

You may get away with it with an A-Head type stem, but I wouldn't advise to do that either.

aesmith
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Postby aesmith » 25 Jan 2009, 10:08am

I think the stress risk would be to the stem, not to the bars. Personally (and at my own risk) I'd probably ream the stem a little with something like fine wet-and-dry round a suitable piece of dowelling. But that would very much depend on the stem, how much material would need to be removed etc etc.

Tony S

willem jongman
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Postby willem jongman » 25 Jan 2009, 10:56am

Bars are known to break at the edge of the stem clamp, and even when their nominal size matched the stem's. It happened to one of my friends, only weeks ago. He was lucky.

JohnW
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Postby JohnW » 25 Jan 2009, 6:30pm

I have broken both bars and stems - and not in prangs.

I have broken two TTT stems and one Cinelli. All were broken underneath the exrension, about where you'd expect the stress to occur as you tightened the binder-bolt. I was using TTT bars in the TTT stems and Cinelli bars in the Cinelli stem. The bars and stems had been purchased together for the sake of compatibility.

I've broken two handlebars - both early GB aluminium bars, and both at the stem - tight up against the clamp. Both were in GB stems.

For a while - about 20-25 years (ish) ago GB made some top quality bars, with central reinforcing sleeve, to fit the standard Cinelli stem - and the ostensibly similar sized TTT stems. I rode these bars for countless thousands of miles, in both Cinelli and TTT stems, and had no problem with either bars or stem.

I never had any problem with later GB bars, or with any GB stem.

I still have a GB Biba stem - again from 20-25 years ago (ish), which is still finished like jewellery and was still going strong (with ITM bars) three or four years ago when I took the bike off the road.

Whenever I had a prang on the traditional quill stems, which could have impacted on the stem, I replace them because cast and forged aluminium could be damaged but unseen, and then go "phut" just when you least expect it.

I think that there is good sense in buying bars and stems together, as being compatible - but as my experience (and many others) shows, this isn't 100% assurance. It is my belief that the A-Head stems are a step forward in safety and practicability.

I have changed my bikes over to A-Head stems on dumb quills, because to me they make life so much easier, and as such make common sense. They aren't as sleek looking as the traditional quill stem, but then, I'm pretty ugly myself.

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Wobbly John
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Postby Wobbly John » 25 Jan 2009, 8:17pm

Image

Nuff said? :shock: