Bicycle Mechanics - Riding with the wrong stem clamp size bad?

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Peek the Geek
04-20-06, 10:17 PM
Hello Bike Forumites. I'm considering going with a shorter stem on my road bike, but want to try before I buy. I've got a shorter stem, but it came off of one of my mountain bikes, and the bar clamp size is 25.4mm.

So the question is, will I do any damage to the bike (or myself) by temporarily using the 25.4mm stem on my 26.0mm bars?

Thanks.

khuon
04-20-06, 10:25 PM
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Peek the Geek
04-20-06, 10:29 PM
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So the 8-Ball is saying I shouldn't do it. What kind of damage would I do?

khuon
04-20-06, 10:38 PM
Crushed bar. Many a handlebar has failed at the stem-clamp area even when the sizes are matched. The difference in curvature from using an undersized clamp will most likely cause a high stress concentration. If you're running an older bar or a steel bar then you'll probably be okay but if it's a semi-modern aluminum bar or CF bar then I would strongly urge you to reconsider such an action.
poopncow
04-21-06, 08:38 AM
I've got a similar situation, but I wouldn't do it (26.0 bar in a 25.4 stem)

stress concentration due to point contact,
plastic deformation, the smaller clamp will want to crush the bar
It just does not fit!

It is like a pair of shoes. If the shoe is slightly big, you can walk around in them and it should be ok,
if you want a snug fit, wear a thicker pair of socks. If the shoe is slightly small, it will hurt...every moment!
Peek the Geek
04-21-06, 09:38 AM
Well poop.

I'm glad I asked. Thanks.