Time Trial Calculator — Estimate TT Finish Time
Estimate your time trial finish time from power, CdA and course distance.
How We Calculate This
Time Trial Physics
On a flat course, your power must overcome two main forces:
- Aerodynamic drag: F_drag = 0.5 * CdA * rho * v^2
- Rolling resistance: F_roll = Crr * m * g
Power at the wheel: Pwheel = (Fdrag + Froll) × v = 0.5 × CdA × rho × v³ + Crr × m × g × v
Your entered power is measured at the cranks, so we first apply a 2.4% drivetrain loss (efficiency 0.976, per Martin et al. 1998) to get power at the wheel. The calculator then solves this cubic equation iteratively using the Newton–Raphson method to find the speed that matches your power. Time is then simply distance ÷ speed.
Default values: air density (rho) = 1.225 kg/m³ at sea level, rolling resistance (Crr) = 0.004 for good road tyres on asphalt.
Frequently Asked Questions
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Last updated: 2025-02-20
All calculations are estimates. Always verify results and consult a professional bike fitter where appropriate.