A Comparison of the Accuracy and Reliability of the Wahoo KICKR and SRM Power Meter

Abstract

The Wahoo KICKR cycling trainer is a new direct-drive electromagnetically braked bike-trainer that allows cyclists to use their own bicycles as ergometer. It is purported to provide ±3% accuracy in power, despite costing considerably less than other cycling ergometers. The purpose of this study was to assess the accuracy and reliability of several KICKR units against the more established SRM power meter using a first-principles based dynamic calibration rig (CALRIG).Five KICKRs and one SRM unit were assessed by a CALRIG-driven incremental test. Following a 15 min warm-up and ‘calibration’ as per manufacturer instructions, power was increased (starting at 50 W) by 50 W every 2 min up to 400 W. Each unit was tested twice non-consecutively, in random order. Data was recorded at 1 Hz, with the last 10 s of each stage being averaged for analysis. The mean error (%) and coefficient of determination (R²) versus CALRIG; as well as the change in mean error and Typical Error of Measurement (TEM) (expressed as a % coefficient of variation) between trials was calculated for each device.The mean error across all KICKR units was -1.5% (range: -3.1% to 0.0%) compared to -1.6% reported by the SRM. R² >0.999 was found for all KICKR units and SRM compared to the CALRIG.  The mean TEM for the KICKRs was 1.5% (range: 1.1% to 1.9%), whereas the SRM reported 0.7%. For test-retest reproducibility, two KICKRs had statistically significant changes in mean error, with an average 1.3% change across all KICKRs. Comparatively, the SRM reported a 0.4% change between trials. The Wahoo KICKR trainer measures power to a similar level of accuracy to the more reputable SRM power meter during an incremental exercise test. Although not as reproducible, the KICKR still demonstrates an acceptable level of reliability for assessing cycling performance.