The development of a conversion table and equations for power estimation in Wattbike AtomX cycle ergometer

Abstract The Wattbike AtomX (Wattbike Ltd.), a cycling ergometer introduced in 2022, features a gear mode with 22 resistance levels. However, the lack of guidelines linking gear and cadence to target power makes its effective use challenging. The aim of this study was to establish a comprehensive reference table and regression equations that relate cadence to power across 22 gears (Study 1). Subsequently, the validity of the predicted power from the equations was assessed by comparing Wattbike AtomXs, along with inter-day reliability (Study 2). These were achieved through a motorized calibrator (Portable Calibrator Ultra, Lode). In Study 1, the ergometer was rotated by the calibrator at 40, 50, 60, 70, 80, 90, 100, 110, 120 and 130 rpm, across gears 1, 3, 5, 7, 9, 11, 13 and 15, enabling us to develop a conversion table from third-order polynomial equations between cadence and power across 22 gears. In Study 2, the equations accurately predicted power across four different Wattbike AtomXs, ranging from 100 to 900 W at cadences of 90 and 110 rpm, with no differences among the ergometers (difference between the measured and the predicted power: − 3.9 ± 1.0 W, − 1.1 ± 0.6%, mean ± SD). Excellent inter-day reliability was also shown in two randomly selected ergometers (ICC: 1.00 for both). In conclusion, the conversion table could become a valid and reliable tool to optimize gear and cadence settings for target power, serving as a valuable resource for exercise training and research with the Wattbike AtomX cycle ergometer.