# Validity of the Quarq Cycling Power Meter

## TL;DR

This study confirms that the Quarq D-Zero power meter accurately measures cycling power output compared to other validated devices.

## Contribution

The study provides direct validation of the Quarq power meter against existing devices, filling a gap in its prior lack of comparison to the SRM gold standard.

## Key findings

- The Quarq power meter showed strong correlations and low variability when compared to the Favero Assioma Duo.
- Significant differences were observed between the Quarq and Hammer Saris H3 devices at higher power outputs.
- The Quarq power meter is valid for measuring cycling power output in both seated and standing positions.

## Abstract

Technological advancements have led to the development of various devices designed to monitor training loads and athletic performance. Power meters, particularly in cycling, allow for the precise quantification of power output, which is crucial for managing training loads and evaluating performance improvements. This study evaluates the validity of the Quarq D-Zero power meter for measuring cycling power output by comparing it with two previously validated devices—the Favero Assioma Duo (FAD) and the Hammer Saris H3 (H3)—noting that, although it shares the same measurement location as the SRM (the gold standard), it has not been directly validated against it. Thirty-one trained male cyclists participated in this study, undergoing tests across various power outputs (100–500 W) and three 10-s sprint efforts. The protocol incorporated different cadences (70, 85, and 100 revolutions per minute), randomized in order, and two cycling positions (seated and standing). Significant differences (p < 0.05) in power readings were observed among the three power meters, except during sprint efforts. However, pairwise comparisons revealed no significant differences (p > 0.05) between the FAD and Quarq power meters, except for the 500 W block. Strong to very strong correlations were observed between the FAD and Quarq power meters (r > 0.883, ICC > 0.879). The coefficient of variation (CV) between the FAD and Quarq devices ranged from 0.62% to 4.89%, and from 0.39% to 6.59% between the H3 and Quarq power meters. In conclusion, the Quarq power meter, integrated into the spider of the bicycle’s bottom bracket, provides valid power output measurements in cycling.