Mechanical efficiency of cycling with a new developed pedal–crank

The mechanical efficiency of cycling with a new pedal–crank prototype (PP) was investigated during an incremental test on a stationary cycloergometer. The efficiency values were compared with those obtained, in the same experimental conditions and with the same subjects, by using a standard pedal–crank system (SP). The main feature of this prototype is that its pedal–crank length changes as a function of the crank angle being maximal during the pushing phase and minimal during the recovery one. This variability was expected to lead to a decrease in the energy requirement of cycling since, for any given thrust, the torque exerted by the pushing leg is increased while the counter-torque exerted by the contra-lateral one is decreased. Whereas no significant differences were found between the two pedal–cranks at low exercise intensities ( =50–200 W), at 250–300 W the oxygen uptake ( , W) was found to be significantly lower and the efficiency ( ) about 2% larger (p<0.05, Wilcoxon test) in the case of PP. Even if the measured difference in efficiency was rather small, it can be calculated that an athlete riding a bicycle equipped with the patented pedal–crank could improve his 1 h record by about 1 km.