Ja. Nedan vad chatgpt säger på ämnet (nej, jag har inte kollat källorna den hänvisar till). Om det stämmer (50-100 w som mest) så torde bromskrafterna på fixie på Götgatan vara klart större.
In maximal sprinting by world-class track or road sprinters, the upstroke contributes little to positive mechanical power and is frequently power-absorbing rather than power-producing.
Instrumented crank and pedal force measurements show that, even at peak sprint outputs of roughly 1,800–2,200 W total, the vast majority of positive work is generated during the downstroke. During the upstroke, elite cyclists primarily unload the rising pedal rather than actively pull it upward with sufficient force to generate substantial positive crank torque. As a consequence, mean upstroke power during a sprint is typically near zero or negative over most of the cycle.
Under the most favorable conditions—very high cadence (≥130–150 rpm), exceptional hip flexor activation, and short transient phases of the pedal cycle—brief positive upstroke power can occur. Even then, reported magnitudes are on the order of tens of watts per leg, rarely exceeding approximately 50–100 W, and only for a small angular sector of the crank rotation. This corresponds to well under 5% of total sprint power and often closer to 1–3%.
Therefore, for an elite cyclist sprinting at world-class level, effective upstroke power is best characterized as minimal, intermittent, and secondary to its primary functional role of reducing negative torque and inertial losses rather than meaningfully augmenting total power output.
Primary sources supporting the quantitative claims about upstroke power in elite sprint cycling include the following peer-reviewed and technical studies:
Ericson, M. O. (1988). Mechanical muscular power output and work during ergometer cycling at different work loads and speeds. European Journal of Applied Physiology, 57(4), 382–387.
This study used instrumented pedals and demonstrated that the upstroke phase is predominantly characterized by unloading rather than net positive power production, even at high intensities.
Coyle, E. F., Feltner, M. E., Kautz, S. A., Hamilton, M. T., Montain, S. J., Baylor, A. M., Abraham, L. D., & Petrek, G. W. (1991). Physiological and biomechanical factors associated with elite endurance cycling performance. Medicine & Science in Sports & Exercise, 23(1), 93–107.
This work quantified crank torque distribution and showed that elite cyclists minimize negative torque on the upstroke but generate negligible positive torque relative to the downstroke.
Kautz, S. A., Feltner, M. E., Coyle, E. F., & Baylor, A. M. (1991). The pedaling technique of elite endurance cyclists: changes with increasing workload at constant cadence. International Journal of Sport Biomechanics, 7(1), 29–53.
This paper provides detailed angular power profiles, demonstrating that even at high workloads the upstroke contributes little or no positive power.
Dorel, S., Couturier, A., Hug, F. (2009). Influence of different racing positions on mechanical and electromyographic patterns during pedaling. Scandinavian Journal of Medicine & Science in Sports, 19(1), 44–54.
High-cadence and high-power conditions showed brief, localized positive upstroke torque in some elite riders, but the magnitude remained small relative to total power.
Sanderson, D. J., & Amoroso, A. T. (2009). The influence of seat height on the mechanical function of the triceps surae muscles during steady-rate cycling. Journal of Electromyography and Kinesiology, 19(6), e465–e471.
This study reinforces the interpretation that upstroke muscle activity primarily serves to reduce resistive forces rather than add substantial propulsive power.
Collectively, these sources converge on the conclusion that, even in world-class sprinting, upstroke power is minimal, transient, and typically on the order of a few tens of watts at most, with its dominant role being the mitigation of negative torque rather than augmentation of total sprint power.
