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  1. #1
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    New to MTB fit. What length stem to start with?

    Expecting my hardtail frame next week and the last pieces of the build are the cockpit components. I feel I have my road fit pretty well down.

    I'm going to be using the Thomson Trail bar. 750mm wide, 12mm rise, 6d backsweep.

    Current road bike
    Stack: 603mm
    Reach: 378mm (57cm TT)
    Stem: 0d 100mm
    Bar: 120mm reach/130mm drop (randonneur bend)

    MTB frame (Lynskey Ridgeline 29SL size L)
    Stack: 651mm
    Reach: 423mm

    If I add some figures to get a general effective "reach" of where I put my hands (assuming same saddle setback for both frames) then I get something like 598mm (378+100+120) for the road bike.

    Doesn't seem that's very useful for choosing a MTB stem as I don't know how to account for the large disparity in handlebar width and the fact that MTB position is generally more upright.

    I realize this is something that you can't just do on paper and it's a trial and error kinda thing, the human body is adaptable, and on and on. But where should I (where would you) start? 70mm 0d stem? Longer? Shorter?

    Thanks!

  2. #2
    I Tried Them ALL... Moderator
    Reputation: Cayenne_Pepa's Avatar
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    I'd start with 70mm.
    "The ONLY person who needs to race.....is the entrant"

  3. #3
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    A complete bike would have been a better choice for a first mtb.
    Just go with the 70, and adjust it if you feel it should be longer or shorter. Though, I'm not sure how you'll know if your stem is the wrong length, because of your limited experience.
    Always get a complete bike for your first one.


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  4. #4
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    Quote Originally Posted by Cayenne_Pepa View Post
    I'd start with 70mm.
    Thank you.


    Quote Originally Posted by ser jameson View Post
    Always get a complete bike for your first one.
    Oh, man. I really messed up.

  5. #5
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    A lot of shops have multiple stems used for testing fit.... that would be where I'd start, in your case.

  6. #6
    Fat-tired Roadie Moderator
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    For that bike, I'd probably start with 80. Maybe even 90 since it sounds like your frames have a smaller reach difference than my road and XC frames.

    I probably use about 10 mm less drop on my XC bikes and land the reach to my grips somewhere between the reach to my flats and to my brake hoods.

    As others have said, start with cheap or, better yet, loaner stems.

    I bumped into a nice comparison of road vs. XC fit over on XC Racing and Training the other day. The poster said that road fit was about power, comfort and aero. MTB fit is about power, comfort and weight distribution. In other words, look for the right fit to let you kick out a lot of Watts, not hurt you, and have neutral handling on climbs and descents. Different MTB disciplines will have different attitudes.

    Pretty bike. Post pics when you get it to the top of something.
    "Don't buy upgrades; ride up grades." -Eddy Merckx

  7. #7
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    Many thanks for the guidance, all.

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