Work out cycling speed from power instantly with clear inputs, formula shown and shareable results.
Speed follows from balancing power against aerodynamic drag, rolling resistance, gradient and drivetrain loss. Because drag grows with the cube of speed the equation must be solved numerically, which this calculator does by Newton iteration. At 200 W with CdA 0.32 on the flat, a rider holds about 32 km/h, with roughly 80% of the power going into pushing air aside.
Power balance
P x drivetrain = 0.5 rho CdA v^3 + Crr m g v + m g v x grade
Drag power
P(air) = 0.5 rho CdA v^3
This is an estimate from population-average equations, not a medical or diagnostic assessment. Individual results vary with genetics, training history and technique. Seek advice from a qualified coach or clinician before making significant changes to training.
Because drag power rises with the cube of speed. Above about 25 km/h it is the majority of your output, which is why position matters more than weight.
About 0.4 upright on the hoods, 0.32 on the drops, 0.28 in the drops with aero kit and 0.22 or lower in a full time-trial position.