Climbing Speed Calculator

Aerodynamic drag grows with the cube of velocity, which turns the power balance equation (power equals speed times the sum of gravity, rolling, and drag forces) into a cubic equation with no simple algebraic solution. Newton's method starts from an estimate and repeatedly refines it, converging within a handful of iterations on the exact speed where your stated power output balances all three resisting forces.

VAM is elevation gain divided by time, expressed as vertical meters climbed per hour, which strips out the specific gradient and distance of any particular climb and leaves a pure measure of how fast you're gaining height. That's why coaches use it to compare a rider's performance on a short, steep climb against a long, gradual one — sustained VAM above roughly 1,700-1,800 m/hr is considered professional-level climbing.

Drag scales with the cube of speed, so its contribution shrinks fast on steep, slow climbs but grows quickly again as gradient eases and speed rises — on a gentle 3-4% grade at high power, drag can become a meaningful fraction of total resistance. Including it keeps the model physically honest across the full gradient range this calculator supports rather than only being accurate on steep pitches.

No — the model assumes steady, seated power output with no wind and no drafting, so it represents an idealized best case for the power you enter. Real-world climbing time will vary with headwind or tailwind, pack dynamics, and the extra cost of standing accelerations, all of which this calculator doesn't attempt to simulate.