Many different protocols are used in sports and medical diagnostics to measure the aerobic capacity of athletes. In sports where the performance itself depends on the high aerobic capacity of the athlete, a progressive load test is most often used. The aim of this study was to determine the reliability of a new measuring instrument for determining aerobic capacity using a progressive load test. The purpose of the research was certainly to bring this way of testing closer to a wider population of athletes, ies to determine the reliability of the ergometer by validation and bring it closer to all clubs so that large sums of money should not be set aside to go to diagnostic centers. The research was conducted on ten examinees of students of the Faculty of Kinesiology, University of Zagreb, with an average age of 22 ± 1. A progressive load test on a bicycle ergometer with an initial resistance of 75W and an increase of 25W every 60 seconds and a cadence maintenance of 60 oct / min was used. After the research, all data were entered into MS Excel and processed in the program Statistica for Windows. Measures of asymmetry (Skewness) and elongation (kurtosis) of the distribution were used to check the sensitivity of the new measuring instrument. The normality of the distribution was checked using the Kolmogorov-Smirnov (KS) test. Validity and reliability were determined using Factor Analysis. The intercoleration coefficient was taken as an indicator of the homogeneity of the variables derived from the protocol implemented on the newly constructed electric bicycle. After the research, the obtained results indicate that the results on the newly constructed electric bicycle ergometer are highly correlated with the results on the already existing ergometer, which confirms the given hypotheses and the goal of the measurement.