Abstract
The aim of this study was to compare the accuracy among a high num-
ber of current mobile cycling power meters used by elite and recrea-
tional cyclists against a first principle-based mathematical model of
treadmill cycling. 54 power meters from 9 manufacturers used by 32
cyclists were calibrated. While the cyclist coasted downhill on a motor-
ised treadmill, a back-pulling system was adjusted to counter the down-
hill force. The system was then loaded 3 times with 4 different masses
while the cyclist pedalled to keep his position. The mean deviation
(trueness) to the model and coefficient of variation (precision) were
analysed. The mean deviations of the power meters were –0.9 ± 3.2%
(mean ± SD) with 6 power meters deviating by more than ± 5%. The co-
efficients of variation of the power meters were 1.2±0.9% (mean±SD),
with Stages varying more than SRM (p < 0.001) and PowerTap
(p < 0.001). In conclusion, current power meters used by elite and rec-
reational cyclists vary considerably in their trueness; precision is gener-
ally high but differs between manufacturers. Calibrating and adjusting
the trueness of every power meter against a first principle-based refer-
ence is advised for accurate measurements.
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