Copyright Velocomp LLP 2005-2014
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APPENDIX 4: Understanding Power Measurement
Consistency and Accuracy
Power meters measure the cyclist’s efforts in watts, and all power meters require initial
setup and calibration.
There are two factors to consider regarding the quality of power measurement:
Consistency
—for the same level of cycling effort, the power number reported is (nearly)
the same each time that same level of effort is achieved
Accuracy
—for any level of cycling, the power number reported is (nearly) correct as
compared to an “absolute” standard.
To illustrate these concepts, consider a marksman using a bow to shoot arrows at a target.
A non-calibrated bow makes good shooting nearly impossible. Without calibration, where
arrows hit (shown by “x” in the illustration below) are nowhere near the bullseye (poor
accuracy), and successive shots do not land close to each other (poor consistency).
Poor accuracy and poor consistency
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