wtf is Q factor

Discussion in '' started by dan de man, Feb 10, 2006.

  1. dan de man

    dan de man Guest


  2. GILD

    GILD Guest

    dan de man wrote:
    > yeah title says it all

    Yes it does, thanx.

    It's got to do with the angle with which a crank points away from the

    Here are two threads with discussions on q-factor.
    'Thread 1' (
    'Thread 2' (


    'three short gs and a long e-flatâ„¢'
    ( - 'world jump
    day' (
    'if i'm murdered, don't execute my killer.'
    'harper' (
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    'Dave' (
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  3. munimanpete

    munimanpete Guest

  4. trials2k

    trials2k Guest

  5. munimanpete

    munimanpete Guest

  6. GILD

    GILD Guest

    ie. Perfectly perpendicular to the axle.


    'three short gs and a long e-flatâ„¢'
    ( - 'world jump
    day' (
    'if i'm murdered, don't execute my killer.'
    'harper' (
    'NAMASTE!' (
    'Dave' (
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  7. U-Turn

    U-Turn Guest

    Q-factor, in practical terms, is how far apart your feet end up (along
    the axle, that is) when you are riding. It's produced mostly by the
    hub, axle, cranks, pedals, and even your footwear, though in some cases
    your saddle and clothing can contribute.

    Each part of the above contributes to Q-factor, but the easiest one to
    think about is the cranks. Even straight cranks contribute to Q-factor
    because they position your feet further out from the midline of the
    wheel. Angled cranks simply position them further out than straight

    In unicycling, the width of the hub and bearings/bearing holders also
    contribute to Q, and can make a difference in both riding comfort and
    the actual power the unicyclist can derive during riding. These
    effects are not absolute, but relative to the rider's physical
    dimensions and riding style.

    The rider's dimensions such as hip width, length and angle of each part
    of his/her legs, degree and direction of pronation and splay footing,
    all interact with the unicycle's Q-factor, and for optimal performance,
    the two should be matched as well as possible. Typically these days
    those factors are ignored, or sometimes an individual rider will
    experiment some on his/her own. Most unicycle equipment does not
    permit a lot of variation in Q-factor, though that situation is slowly

    However, distance riders (especially) should be aware that the many
    100s of thousands of revolutions they do (order of magnitude courtesy
    of Andy Cotter) are affected by Q-factor's interaction with their
    personal body characteristics, and may derive substantial benefit by
    working with different crank angles, hub widths, saddles, and pedal


    Weep in the dojo... laugh on the battlefield.
    'LiveWire Unicycles' (
    'Strongest Coker Wheel in the World'
    '29er Tire Study' (
    'New York Unicycle Club' (
    -- Dave Stockton
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  8. Mikefule

    Mikefule Guest

    The unicycle rolls on a narrow strip of tyre. Even on a fat tyre, the
    contact patch is only a couple of centimetres wide on flat ground.

    The pedals are some distance to each side of this contact patch.

    The Q factor is this distance.

    Why does it matter?

    Because the weight of the crank, pedal and foot (and leg) adds up to
    quite a lot, and the pedal is "orbiting" the axle. "Centrifugal force"
    (yes, I know, but we all know what it means) means that the pedal is
    constantly pulling away from the axle. The heavier the pedal and the
    faster the rpm, the more it pulls.

    So, the further out from the contact patch the pedal is, the longer the
    lever (the axle) it is pulling on, so the more it affects the

    Think about this: if the right pedal is pulling the right hand end of
    the axle one way, then the left pedal is paulling the left hand end of
    the axle in exactly the opposite direction.

    For a simple demonstration of the effect, hold your uni up by the seat,
    then spin the wheel hard with your other hand. The uni will wobble
    jerkily from side to side in time with the rotation of the wheel.

    If (for the sake of demonstration) you removed the cranks and pedals
    and repeated the experiment, the uni would NOT wobble jerkily from side
    to side.

    Now, if you increase the Q factor, the degree of jerky wobbling will
    increase. if you reduce the Q factor, the degree of jerky wobbling
    will increase.

    When you are riding, you may not notice the effect except at very high
    speeds, but nevertheless it is there, and you are using energy to
    compensate for it.

    On the other hand, a high Q factor is good for steering, especially
    with a large wheel.

    Like everything in unicycling, it's a compromise.


    "...some of the basic stuff, like not killing each other, should be
    relatively obvious to anyone."

    John Foss, the unicycling philosopher, goes right to the point.:)
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  9. tholub

    tholub Guest

    As I mentioned in another thread, Q factor is *not* whether the cranks
    are angled or not; it's the distance between the foot platforms of the
    pedals. A wide hub with straight cranks can have a larger Q-factor
    than a narrow hub with angled cranks.

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