The metabolic cost of submaximal cycling is set by power output and pedal speed; crank length (145–195 mm) has no independent effect
Key Findings
Metabolic cost was determined by power output and pedal speed (R² = 0.99); neither crank length (145–195 mm) nor pedalling rate added anything.
Nine trained male cyclists; cranks of 145, 170 and 195 mm; 40, 60, 80 and 100 rpm; power at 30, 60 and 90% of lactate threshold.
Mechanical power output, pedal speed and pedal speed squared determined metabolic cost (R² = 0.99 ± 0.01).
Neither pedalling rate nor crank length contributed significantly to the model.
Practical Application
A different crank will not make an endurance rider more or less economical. What costs energy is foot speed — crank length multiplied by cadence — so a shorter crank at a slightly higher cadence costs the same.
For a long event or an ultra, choose the crank by joint comfort and position, not by expected efficiency.
Limitations
N = 9, men only, 25 mm steps, intensities below lactate threshold; abstract only was read.