The Physics of Riding

Total power P = ½ρ·CdA·v³ + Crr·m·g·v + m·g·sin(θ)·v. The first term is aerodynamic drag, proportional to the cube of air speed — why speed gets exponentially harder. The second is rolling resistance. The third is gravity, the dominant cost on climbs. This cycling power calculator applies the standard model with your mass, speed, gradient, and equipment parameters.

Typical Parameters

Road cyclist CdA: 0.28–0.36 m² (0.24 with aero bars). Rolling resistance: 0.003–0.006 for road tires on asphalt. Air density: 1.225 kg/m³ at sea level, dropping to ~1.06 at 1,500 m — a free speed boost at altitude.

Training with Power

Functional Threshold Power (FTP) is the power you can hold for one hour. Train at 55–75% of FTP for endurance, 90–105% for threshold, and 120%+ for VO2 max intervals. W/kg targets help pace climbs: at 4.0 W/kg you climb roughly 1,200 m per hour on moderate grades.