CdA Estimator
Estimate your aerodynamic drag area (CdA) from a steady effort by inverting the Martin et al. (1998) cycling power model
Inputs
Mean power over a long, steady effort
Mean ground speed over the same effort
Net gradient of the segment — flat is most reliable; descents bias the estimate
0.003 road clincher, 0.005 training tyre
Positive = headwind, negative = tailwind
Measured station pressure — leave blank to estimate from altitude
Humid air is less dense, so it lowers your estimated CdA slightly
Results
Relaxed / tops — Upright-ish endurance position.
Power breakdown
Power distribution
- Aerodynamic
- Drivetrain loss
- Rolling
Best estimated from a long, steady, ~flat effort where you are neither accelerating nor coasting. The model has no kinetic term, so surges, descents, and braking bias the result.
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