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Homework Help: How to calculate resultant force for a bike pedal stroke

  1. Aug 12, 2017 #1
    1. The problem statement, all variables and given/known data
    To calculate the resultant pedal force from the variables given: Crank (degrees) measured clockwise from vertical, spindle (degrees) measured anti-clockwise from horizontal, tangent force (N) applied to the pedal surface, normal force (N) applied to the pedal surface and torque (Nm). For example a given reading is

    Crank: 10° Spindle: -18.21° Tangent force: 55.96N Normal force: -126.7N Torque: 6.4Nm

    Any help that can be provided is greatly appreciated.

    2. Relevant equations

    3. The attempt at a solution
    I have been attempting to use equations with the tangent and normal forces acting as x and y. Then using the spindle angle to try and calculate the resultant force with little success.
  2. jcsd
  3. Aug 12, 2017 #2


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    Please tell us what the actual problem is ? Forces on a bike pedal is a bit too vague . How about posting a diagram ?
  4. Aug 12, 2017 #3
    This is what I have been given

    Part 1

    You have been given pedalling force data for 10 cyclists to analyse. Write a Matlab code to calculate the following for each cyclist:

    Throughout the pedal stroke (i.e. additional columns of data):

    •  Resultant pedal force (F RESULTANT)
    •  Force tangential to the crank arm (crank arm length = 170 mm) (i.e. the effective pedal force, F EFFECTIVE)
    Each worksheet contains the data for one cyclist and the five columns to data are:

    1. CRANK crank angle measured clockwise from top dead centre (i.e. vertical pointing upwards)

    2. SPINDLE
    pedal spindle angle measured anti-clockwise from horizontal

    Ft and Fn
    are the forces applied to the pedals tangential and normal to the pedal

    4. TORQUE torque applied to turning the crank arm (TCRANK)
  5. Aug 12, 2017 #4


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    I would suggest making your own diagram showing that info if not given one.
  6. Aug 12, 2017 #5


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    Based on that, I would guess you are to assume no frictional force between shoe and pedal.
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