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  1. #1
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    head tube angle and stem length

    the relation between head tube angle and stem length: is it simple enough to be described in some kind of formula? what i mean is this: the steering is quickened if i choose a shorter stem and it becomes slower if i choose a frame with a slacker head tube angle: but can a 68 degrees frame be set up to be as quick in steering as a 70 degree frame: by varying the stem length? does a 71 degrees 120 mm correspond to say a 69 degrees 50 mm? does one slacker degree need 30 mm of shorter stem to retain steering quickness for example? or is the head tube angle much more decisive than the stem length? thanks rasmus

  2. #2
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    I can sort of see what your trying to say but if it was that easy every frame would be the same angle and just vary stem lengths and rises,
    you have to also take into account by lengthening or shortening a stem you are also altering the effective top tube length (TT + Stem and rise) this could mean you get your desired steering but be uncomfortable because you are to stretched or hunched.

  3. #3
    Nouveau Retrogrouch SuperModerator
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    No, not really. Stem length is for fit and weight distribution. It does change the handling but not in the same manner as HTA changes.
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  4. #4
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    a question I've been dying to ask I think may be realted:

    let's say I'm riding a crappy old trek xc bike from the year 2000 (that I love to ride). It is set up with a xc susp fork that probably was marketed as having 3" of susp but probably more like 2". What will the effect to the steering be if I throw on a fork that has 120mm(4"?) of travel? What about a 5" travel fork?

  5. #5
    Paste eater
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    every inch of travel will change the HT angle ~1inch. BTW 5 inches is prolly a bit much of a XC ride...

  6. #6
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    Quote Originally Posted by Eerie
    a question I've been dying to ask I think may be realted:

    let's say I'm riding a crappy old trek xc bike from the year 2000 (that I love to ride). It is set up with a xc susp fork that probably was marketed as having 3" of susp but probably more like 2". What will the effect to the steering be if I throw on a fork that has 120mm(4"?) of travel? What about a 5" travel fork?
    You will slacken the head angle and slow down the steering.

  7. #7
    MK_
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    Your climbing will suffer and you'll be more prone to popping wheelies on steep climbs. The bike will be harder to tame on the ups. On the downs you'll be rewarded with increased confidence and stability and plushness. Your steering will slow down, but you can make up the difference there, at least to an extend, with a shorter stem.

    You risk ripping off the head tube, though, as frames of that vintage designed with such short travel forks are not reinforced properly to be ran with a nearly 5in (120mm) fork. Stick to a 4in, 100mm and you should be good.

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  8. #8
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    Bumping a 12- year old thread so we can see how perspectives have changed.

    Is there a point where a stem is too short for a bike with a 71 degree HA? Too long for a 65 HA?
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  9. #9
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    I was like, "what is this, 2006?!". And yes, yes it was.

    Xc bikes get a long ass 50mm stem. Everything else gets <50mm. I don't think there's necessarily a relationship to hta.

  10. #10
    Out spokin'
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    Quote Originally Posted by mack_turtle View Post
    Is there a point where a stem is too short for a bike with a 71 degree HA? Too long for a 65 HA?
    Nice twelve year old pluck, Mack.

    I just sold a size large Guerrilla Gravity frame because it required a 65mm stem to fit me properly.
    And I just ordered a size XL Guerrilla Gravity frame on which I'll employ a 32mm stem to give me identical saddle-to-bar dimension* as my previous large frame.

    So I hope 32mm isn't too short with a 65 degree HA, cuz I'll be using the shortest standard-design stem available.

    Anyway to the point, I don't believe stem length affects handling as much as HA does, or at least one doesn't make up for the other. I'm switching frame sizes because I want my front wheel that much farther away from me (plus I'm tired of having a frame that requires 67mm of spacers under the stem).

    Which will affect handling more? A front wheel that's 1.25" farther away from the rider or a stem that's 1.25" shorter? I won't be able to tell since I'm making both changes at the same time.
    =sParty

    *What is saddle-to-bar dimension called? It's not reach. It's not ETT. I don't think there's a name for it other than distance from saddle to bar.
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