What if you could
climb it differently?
One climb. Two scenarios. Change your weight, power, tyres or riding position and see how much time you could gain.
Define the climb
Choose the approximate altitude of the climb, not its elevation gain. The same value is applied to scenarios A and B.
Change the variables
The climb is the same for both scenarios. Speed and air density affect the impact of each riding position.
Starting point
What if…?
You would reach the top sooner in B
How is this estimate calculated?
The calculator assumes a constant gradient, no wind and constant average power. It combines gravity, rolling resistance and aerodynamic drag, with a drivetrain efficiency of 97.5%. Each riding position uses an indicative fixed CdA, but its effect is not fixed: the power required to overcome aerodynamic drag is ½ × air density × CdA × speed³ . This is why aerodynamics matter much more at 40 km/h than at 15 km/h. At higher altitude, lower air density reduces this effect.
The tyre and road-surface options use Crr values of 0.003 / 0.004 / 0.006 / 0.008, while the riding positions use CdA values of 0.40 / 0.32 / 0.28 / 0.25 m². The four altitude options use air densities of 1.20 / 1.11 / 1.01 / 0.91 kg/m³ for approximate altitudes of 200 / 1,000 / 2,000 / 3,000 m.
These are indicative values, not personal measurements. Crr also depends on the tyre and its pressure, while actual CdA can vary with the rider, position, equipment and airflow conditions. This tool does not have an individual aerodynamic measurement with which to recalculate your CdA at different speeds. The power entered is the average power you maintain throughout the climb, not necessarily your FTP. Changes in gradient, wind, temperature, road surface and stops can all affect the final time.
- Martin et al.: cycling power model for combining gravity, rolling resistance and aerodynamic drag.
- NASA: aerodynamic drag equation for the relationship between CdA, air density and speed.
- Bicycle Rolling Resistance: testing methodology and road tyre test results as guidance for the rolling-resistance categories.
- Review of cycling aerodynamics for the effect of riding position on CdA.
- NASA: standard atmosphere tables for the approximate relationship between altitude and air density.
The specific Crr and CdA values are simplified categories selected for this tool. They have not been measured on your bicycle and should not be interpreted as an exact set of values taken from any single source above.