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Power Measurement: Accelerations |
Extra Mass When AcceleratingCommon wisdom says that a rider has a large acceleration at the start and many smaller, not-very-significant ones thereafter. Is this true?The plots show positive (yellow) and negative (red) accelerations where power was greater than zero. These are the places where a rider was applying power, places where extra weight matters. (One assumes that if power was zero, i.e. coasting or braking, extra weight is not an issue.) Extra weight helps a rider when deceleration (for example, extra weight when a wind gust hits could help a rider) and works against the rider when accelerating. The net benefit by applying these accelerations to a 1 kg mass is given. In the first plot, the total energy for the ride was 343 kJ. The extra energy, 36 kJ, for a 1 kg mass is significant in relation to the total energy for the ride. The energy changes depending on which segment of the data was selected for viewing.  Net Energy for these accelerations for a 1 kg mass = 36.36 kJ Here is a short, flat time trial (a different ride from the one above) where the total energy was 130 kJ:  Net Energy for these accelerations for a 1 kg mass = -0.54 kJ One may notice that acceleration data plots in lines. This is because the data is recorded with only a few digits; thus the "granularity" of the data. Accelerations: Road, ErgometerThe two plots below show the frequency distribution for Accelerations on the road and on an Ergometer. Notice that there is an order of magnitude difference between one and the other. Frequencies distribution for Accelerations during a road time trial.  Frequency distribution for Accelerations during an Ergometer test. |