Work out cycling power output instantly with clear inputs, formula shown and shareable results.
Cycling power splits into aerodynamic drag (rising with the cube of speed), climbing power (weight times gradient times speed) and rolling resistance. On the flat above 25 km/h aerodynamics dominate; on a climb above about 5% gravity dominates and position matters far less.
Cycling power
P = 0.5 rho CdA v^3 + m g (gradient) v + Crr m g v, all divided by drivetrain efficiency
Because aero power scales with v cubed and is the largest term at speed. On a steep climb speed is low, so drag is small and weight dominates.
0.40 m2 upright on the hoods, 0.30-0.32 in the drops, 0.25 in a good time trial position and under 0.20 for elite TT riders.