Recent content by JasonFit

  1. J

    I Energy input\losses for a cyclist accelerating from a standing start

    Your calculations match mine for the power to accelerate (654W) but I think you have plugged in different values for the steady speed calculation. I’m using a CdA of 0.25 (0.5 for the coefficient and 0.5 for the area - this is a bit generous but not a big factor at the slow start). The rolling...
  2. J

    I Energy input\losses for a cyclist accelerating from a standing start

    :) this is true but that is the role I have taken on - to analyse every aspect of the cyclists performance. First I want to make sure I’m accounting for all the energy expenditure correctly. It would be good to be able to quantify the difference in those first seconds between a big gear and...
  3. J

    I Energy input\losses for a cyclist accelerating from a standing start

    Ok what I mean is that if the cyclist is held in the gate while he is applying all that force on the pedals (and handlebars) he would soon become exhausted having moved nowhere - that’s what I meant by wasted (to heat?). I’m now trying to determine what amount of energy is being wasted by...
  4. J

    I Energy input\losses for a cyclist accelerating from a standing start

    Getting back to the physics - would the additional energy consumption simply be the force (torque) applied to the pedals?
  5. J

    I Energy input\losses for a cyclist accelerating from a standing start

    I realize that I’m now moving away from physics but can anyone explain how/what is consuming that energy when nothing moves?
  6. J

    I Energy input\losses for a cyclist accelerating from a standing start

    Correction it was 7.5m/s in this example.
  7. J

    I Energy input\losses for a cyclist accelerating from a standing start

    6.25m/s - that's how I got to the 654W
  8. J

    I Energy input\losses for a cyclist accelerating from a standing start

    Ah ok I think I'm seeing the light! So this is more of a biomechanical issue with the body struggling to get the pedals turning. Any ideas where that extra (inefficient) energy is going - heat?
  9. J

    I Energy input\losses for a cyclist accelerating from a standing start

    Yes these are all factors to take into consideration for other situations but I'm specifically trying to understand the first few seconds of acceleration and how the power doesn't seem to match the exertion (i.e. max effort but power numbers lower than later in the ride when pedalling at speed...
  10. J

    I Energy input\losses for a cyclist accelerating from a standing start

    I am only concerned about the initial few seconds or less, so the speed is very low.
  11. J

    I Energy input\losses for a cyclist accelerating from a standing start

    Average velocity id taken from moving 15m in 4secs (15 / 4 = 3.75). I didn't include the rotational moment of inertia as I've seen this as pretty minor in previous calculations. Correct me if I'm wrong!
  12. J

    I Energy input\losses for a cyclist accelerating from a standing start

    Yes he was on a track bike (63:15 fixed gearing). I took another look at my video analysis and calculated the power for the first 1m (0.85secs) and you're correct, the calculated power is even lower (about 300W)! Which adds further to my original question which is why does the cyclist seem to be...
  13. J

    I Energy input\losses for a cyclist accelerating from a standing start

    I have been analysing the power that a cyclist puts out during a standing start and the numbers don't seem to match the effort that is going in! Here's a real example: Cyclist (93kg incl bike) moves 15m from standing start in 4secs (average velocity 3.75m/s). Assuming a constant acceleration, of...
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