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Forces on a motorcyclist

  1. Jul 26, 2017 #1
    I have never studied any form of mathematics other than through 'getting through life' and working stuff out and trying to understand the mechanics/ physics in terms I understand. Non scientific / mathematical terms but words in English.
    I have a few questions I would like to ask a physicist to explain in words and terms I understand.
    Along the way I am sure I could get to know some interesting characters and learn your terms to my thinking.

    Q. What are all the forces in play with a motorcyclist negotiating a corner at speed, and leaning into the corner by moving his/ her mass off the bike (and down), in order to reduce the angle of lean of the bike itself.
    Thank you.
  2. jcsd
  3. Jul 26, 2017 #2
    Consider the tyres to be radial with as much traction on it's overall surface, whilst in a constant state of rest.
    Consider the centre of gravity to be midway between the two wheels in a constant state of rest.
    The rider weighs half as much as the bike.
    What else?
  4. Jul 26, 2017 #3


    Staff: Mentor

    Moderator's note: moved to General Physics forum.
  5. Jul 26, 2017 #4
    Taking your question literally ("all the forces in play") there are three forces:
    Friction between tyres and road
    Wind resistance
    The net friction force will be due to the combination of motor; braking and the centripetal force required to turn the corner. If you ignore wind resistance and assume no acceleration from the motor or application of brakes it gets much simpler, (but still complicated, just not as complicated).
    The cornering characteristics of any bike will be determined by factors which include, but are not restricted to, the head angle, rake and trail of the fork; the position of the centre of mass (including its height!); the coefficient of friction of the tyre/road interface and the wheelbase.
    When a rider shifts his or her body to one side relative to the centre line of the bike they are trying to alter the cornering characteristics to compensate for what they perceive as a lack in those characteristics. An ideal combination of rider and bike would perform optimally without the rider needing to do this. (The ideal rider probably has zero mass!)
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