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  1. #1
    Hack Racer
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    31.8 vs 25.4 mm handlebar setups

    Been researching handlebars looking for a upgrade for lighter weight. I did a search on "handlebar" and went through 8 pages looking for:

    Is 31.8 mm handlebar better than 25.4 mm?

    and found no answer

    Specialized equipped my stumpjumper with a 31.8 mm handle bar and stem. Logic says that a bigger diameter tube will be stronger than a thinner tube if equal wall thickness. It can also be said that you can get a lighter tube by going thicker and using a thinner wall.

    BUT, for handle bars they all taper back down to 25.4 so that you can mount shifters, brakes, and grips on. So the taper point is the weakest point as all the stress will be concetrated there.

    So then the question is why 31.8mm? to have a bigger diameter to clamp on so that the bar doesn't rotate as easy?

    My stumpjumper is a hardtail which is setup for XC racing. (atleast I'm trying to squeeze every last bit out of the bike). I see 25.4 mm handle bars more common, and lighter. 25.4 mm stems are also lighter.

    I run a flat bar so I'm not too worried about the bar twisting on me...

    suggestions? Comments?

    Thanks

  2. #2
    STS
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    in mtb 31.8 don't have any logic
    weights more
    you can't apreciate the rigidity gain

    it's just marketing and aesthetic

  3. #3
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    The quality and execution of a design has FAR more to do with stiffness than the standard (31.8 or 25.4) it is built on.

    BM
    "I've come to believe that common sense is not that common" - Matt Timmerman

  4. #4
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    Quote Originally Posted by STS
    in mtb 31.8 don't have any logic
    weights more
    you can't apreciate the rigidity gain

    it's just marketing and aesthetic

    So whats the logic for road bikes then? That same logic should carry over to MTB right?

  5. #5
    Hack Racer
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    Quote Originally Posted by bmadau
    The quality and execution of a design has FAR more to do with stiffness than the standard (31.8 or 25.4) it is built on.

    BM

    "quality and execution of a design..."?

    so the only purpose of it is to make the object more appealing to the eye? Isn't the most important aspect for a race bike (which most people have or are interested in this forum) to optimize it for performance. Which in this case would be to optimize stiffness (increase) and to decrease weight?

  6. #6
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    1: the area where the grips, brake and shifters mount is 7/8" not 25.4; most bars have a taper regardless of stem diameter.

    2: yeah a larger diameter is stiffer but how much talk of "vibration damping" or "compliance" do you hear. "compliance" is what you call "flex" when you want it to sound like a positive quality.

    biggest advantage I see to 31.8 is you can use road stems, which may or may not be lighter. Thompson x2 vs x4 for example. x2 is pleanty strong enough for you if you are the type or person that worries about weight, and is lighter than x4.

    I went with 31.8 on my most recent bike just because I'd like to see 25.4 and 26.0 go away - I don't care what the new standard is so long as it's the same road or mtn.

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