Evaluation of the Cyclus cycle ergometer and the Stages power meter for measurement of power output in cycling

Abstract

The purpose of the present study was to evaluate two commercially available power meters: the Cyclus ergometer (CYC) and the Stages power meter (STA) in comparison to a highly-validated power meter (SRM). Ten trained cyclists (mean ± SD; age 24 ± 8 y, body mass 69.7 ± 7.3 kg) performed an incremental exercise test to exhaustion (GXT), 2 x 10 sec sprints (10ST) and a 1-min test (1minTT) on a bicycle attached to a cycle ergometer (CYC). The bicycle was also fitted with the SRM cranks and the STA power meter. Power output (W) for the CYC and STA for each test was compared to the SRM to determine the validity of the devices. The coefficient of variation (CV) for the STA vs SRM during the GXT was 2.4 ±1.1% (±90% CL) and 2.3 ±0.9% for the CYC vs SRM.  For the 1minTT, the STA vs SRM had a CV of 3.4 ±1.6% and 3.0% ±1.6% for CYC vs SRM. Comparison between power meters during the 10ST showed a CV of 18.2 ±1.6% for STA vs SRM and 13.7 ±1.6% for CYC vs SRM. In summary, both the CYC and STA are practical, easy to use devices and exhibit an acceptable level of agreement during low (< ~500W), but not high (> ~650W) power outputs.