Using road stem on an mtb? is it safe?
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  1. #1
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    Using road stem on an mtb? is it safe?

    I want to replace my mtb stem with a longer road stem. However, the mtb stem is oversized, i.e., it has a wider contact area at the end that clamps onto the handlebars. The road stem is just your typical roadie stem.

    So the question is, can I use the road stem on my mtb bike safely? The narrower road stem put more pressure per square in on the handlebars, but will this be a too big of a risk?

    I'm to save a few bucks, but somehow my gut feeling is telling to get an oversized stem. Opinions?

  2. #2
    gazing from the shadows
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    Can you? Probably. The question is for how long.

    What stem? What bar? Are we talking light stuff or heavier? Narrower or wider bars? Consider not only the clamping forces, but the fact that the bars will have a longer lever arm from the support point, meaning more flex for each hit. Consider what trails you ride and how you ride it.

    Really, you know the answer. Saving a few bucks and worrying about one of the worst types of crashes I can imagine (sudden bar/stem failure on a downhill when taking a big hit) seems not worth the few bucks (your words) saved.
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  3. #3
    tlg
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    "MTB" means a lot of things.

    One of these I'd use a road stem... the other... ehhhh probably not.


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    Handlebars is 630mm wide (bar was 690mm wide that was cut down to 630), and it's carbon. The bike is a hardtail and I do often use it on trails that is about 80% as rough as the second picture above, with plenty of 1-1.5 ft drops and rockbed with basketball sized rocks.

    well folks, i'm just gonna buy an oversized mtb stem, cheaper than dental implants

  5. #5
    tlg
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    Quote Originally Posted by aclinjury View Post
    trails that is about 80% as rough as the second picture above, with plenty of 1-1.5 ft drops and rockbed with basketball sized rocks.
    Well that's a no brainer. MTB stem!
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  6. #6
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    mtb stem it is!

  7. #7
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    wow, for once, reason won out!
    We can all (momentarily) rejoice!

  8. #8
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    Quote Originally Posted by tlg View Post
    Well that's a no brainer. MTB stem!
    What'll blow your mind and spark discussion...I have an MTB stem that specifically says "FOR MTB USE ONLY".
    "Refreshingly Unconcerned With The Vulgar Exigencies Of Veracity "

  9. #9
    tlg
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    Quote Originally Posted by Marc View Post
    What'll blow your mind and spark discussion...I have an MTB stem that specifically says "FOR MTB USE ONLY".
    ok...don't know if my mind is blown... but what makes it MTB only? Will it make your road bike too heavy to ride?

  10. #10
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    Quote Originally Posted by tlg View Post
    ok...don't know if my mind is blown... but what makes it MTB only? Will it make your road bike too heavy to ride?
    You got me.

    https://www.promaxcomponents.com/product/da-1-stem/

    Came out of the box with a label saying what I said.
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  11. #11
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    Quote Originally Posted by Marc View Post
    You got me.

    https://www.promaxcomponents.com/product/da-1-stem/

    Came out of the box with a label saying what I said.
    I see that stem is spec'd at 15Nm of torque (for the end that clamps onto the bars). I believe this torque number is higher than most road stem specs. Based on this, I suppose if a person used this stem with a road bars, then he could potentially over tighten the stem and put the road bars at risk?

  12. #12
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    Quote Originally Posted by tlg View Post
    ok...don't know if my mind is blown... but what makes it MTB only? Will it make your road bike too heavy to ride?
    perhaps not for motorized use?

  13. #13
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    Kalloy Uno stems seem to be unproblematic for trail riding.

    https://forums.mtbr.com/weight-weeni...0-1094616.html

  14. #14
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    Quote Originally Posted by rideit View Post
    wow, for once, reason won out!
    We can all (momentarily) rejoice!
    Not so fast there, rideit.

    I'm sure us RBR'ers can extend this burning question into a month long fight.

  15. #15
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    For years and years there were mountain bikes, road bikes, and 'stems'. Just stems. Seems like nearly all of us lived through this very dangerous era.
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  16. #16
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    Quote Originally Posted by cxwrench View Post
    For years and years there were mountain bikes, road bikes, and 'stems'. Just stems.
    Seems to me I remember a time when knowing the difference between 26.0 and 25.4 was pretty important when swapping out a stem. And if you told your LBS you needed a stem, they would ask "road or mtb?" as an easy way to know which size was needed.

    Will a Thomson x2 120mm work on an MTB? That's listed as a road stem at CO Cyclist. Sure, but I think I would rather have the X4, listed as an MTB stem (which is 30 grams heavier for the 120mm size). The X2 has quite a bit cut out of the face plate, and two versus four bolts.

    Specs are specs, but road/mtb labels generally correlate with different specs pretty well.
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  17. #17
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    Quote Originally Posted by QuiQuaeQuod View Post
    Seems to me I remember a time when knowing the difference between 26.0 and 25.4 was pretty important when swapping out a stem. And if you told your LBS you needed a stem, they would ask "road or mtb?" as an easy way to know which size was needed.

    Will a Thomson x2 120mm work on an MTB? That's listed as a road stem at CO Cyclist. Sure, but I think I would rather have the X4, listed as an MTB stem (which is 30 grams heavier for the 120mm size). The X2 has quite a bit cut out of the face plate, and two versus four bolts.

    Specs are specs, but road/mtb labels generally correlate with different specs pretty well.
    Yes the clamp size was different but the construction was the same.
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  18. #18
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    Quote Originally Posted by cxwrench View Post
    Yes the clamp size was different but the construction was the same.
    And is the construction the same today?

    Not in the example I provided, though I don't know overall. Hard to find direct comps, given so many stubby mtb stems.
    .
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  19. #19
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    Quote Originally Posted by QuiQuaeQuod View Post
    And is the construction the same today?

    Not in the example I provided, though I don't know overall. Hard to find direct comps, given so many stubby mtb stems.
    On the lower end stems that Bontrager does they're pretty much the same, the high end stuff looks different. Carbon for road and really short, stubby, 35.0mm dia mtn stems.
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  20. #20
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    Quote Originally Posted by cxwrench View Post
    For years and years there were mountain bikes, road bikes, and 'stems'. Just stems. Seems like nearly all of us lived through this very dangerous era.
    I'm guessing back in the day, they generally just over built them stems, so they just called it stems. But nowaday, in the age of carbon and weightweenie components, I think I'd be interested in knowing if a road stem is mtb worthy. For example, the Zipp Course aluminum stem has really thin sidewall, no wonder it weighs so little.

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