How does stem length effect steering?- Mtbr.com
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  1. #1

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    How does stem length effect steering?

    I'm thinking of getting a shorter stem. I'm thinking of getting a block stem for durability, but it is about half the distance as my current bar stem.

    How does stem length effect steering? Will I have quicker steering with a shorter stem or longer stem? Does the stem only effect how far my hands go?

  2. #2
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    alot, what are you planning on doing w/ the bike?

  3. #3

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    The longer the stem the slower it will steer.
    The slacker the head angle the slower it will steer
    The wider the handle bar the slower it will steer.
    You will get used to a new stem, you can get some quite long block stems, long pipe stems are just silly anyway.

  4. #4

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    I'm more of an Aggro XC- Light freerider

    So a shorter stem will quicken my steering? Sounds good to me.

  5. #5
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    i feel it the other way. long stem = twitchy steering, short stem = more stable. what length are you running now? and what is you reason to change? unhappy with the feel?

  6. #6
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    Quote Originally Posted by rpl3000
    i feel it the other way. long stem = twitchy steering, short stem = more stable. what length are you running now? and what is you reason to change? unhappy with the feel?
    ?????????????

    It's not a question of feel. Just physics. Shorter stem=quicker steering. Longer stem=slower/more stable. Just like steering angle or fork rake, it's not really a "feel" sorta thing.

  7. #7
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    Quote Originally Posted by BudhaGoodha
    I'm thinking of getting a shorter stem. I'm thinking of getting a block stem for durability, but it is about half the distance as my current bar stem.

    How does stem length effect steering? Will I have quicker steering with a shorter stem or longer stem? Does the stem only effect how far my hands go?
    You need to also account for the front to back balance of the bike. A shorter stem will shift the CG of the bike towards the back. This will cause your front tire to plow unless you make a concious effort to move your weight to the front during the turn. Climbing may also be a problem because the front tire wanting to lift off the ground. Again shifting more weight to the front will solve this problem.

    I like riding with shorter stems. Just had to make sure the front was weighted more than if I was using a longer stem.

  8. #8

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    Quote Originally Posted by huh
    You need to also account for the front to back balance of the bike. A shorter stem will shift the CG of the bike towards the back. This will cause your front tire to plow unless you make a concious effort to move your weight to the front during the turn. Climbing may also be a problem because the front tire wanting to lift off the ground. Again shifting more weight to the front will solve this problem.
    agree, and to add there is sort of an odd caster effect involved with stem length, where longer stem equals more caster (assuming your hands are on the bar of course).

    its funny cus stem length seems to be one of the more complicated geometries as far as physics, since theres this whole interaction between ergonomics, HA and offset (trail) and associated relative movements and forces. I've noticed that stem lengths shorter than the forks offset seem to become undesirable; not sure if its related or coincidental.

    so, uhh, just experiment.

  9. #9

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    just get something in between long and short and you will be right. 60mm sounds about right.

  10. #10
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    Quote Originally Posted by Go Kart Motzart
    ?????????????

    It's not a question of feel. Just physics. Shorter stem=quicker steering. Longer stem=slower/more stable. Just like steering angle or fork rake, it's not really a "feel" sorta thing.

    or more like dynamics... .which happens to be my expertise. the angular velocity of which you decide to turn the bars give precisely the same angular velocity of the wheel or at the wheel depending on how you want to say it regardless of stem length (its a rigid body). angular accelerations follow the same rules, so as far as steering quickness, it is about feel.

    now for the moment transformation laws..... the force on the bars (input from your hands) will be different for two different lenght stems, but thats a little more intuitive like a lever.

  11. #11

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    Its about physics, a longer stem will make it feel slower because there is more leverage on the wheel.

  12. #12
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    Quote Originally Posted by Chingy
    Its about physics, a longer stem will make it feel slower because there is more leverage on the wheel.
    alright, if you put the same torque on the wheel, then for a longer stem you would have to use less force on the bars. imagine a breaker bar length stem to get the picture. this would lead to bike that had alot of movement at the bars because of the stem length, thus leading to a "quicker feeling" to the steering.

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    bah, i'm going against all you and saying its about the relative bar movement vs. how your arms control the bars. Bars further out have more of a side-to-side movement, closer bars have more of a front to back movement. That side to side movement is much harder to control ergonomically and remain precise, therefor feels twitchy and less controllable.

    You guys are thinking too much about slight deviations in torque magnitudes when the body can easily overcome them anyways; the forces involved in steering your bike with your arms are insignificant compared to your actual strength. However the finer control aspects of these motions is quite different, since turning or controlling your bars is a reactive movement, not a proactive one. Being stretched out with longer stems only compounds the control problem, since your arms are straighter and more perpendicular to the actual directional motion of your grips.

    anyone feel me on this?

  14. #14
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    dude, i solve dynamics problems all freaking day. i'm checking out of this thread.

    longer stems feel twitchy and are thus not used by many of us. i'm sticking to it.

  15. #15

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    Longer stems do not feel twitchy because they steer slower and you have more leverage to overcome wheel wandering.
    Last edited by Chingy; 12-09-2004 at 02:07 AM.

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