Bike Speed Calculator
Pedal Science’s calculator estimates bike speed from rider power using aerodynamic drag, rolling resistance, wind, we...
What Bike Speed Calculator does
Pedal Science’s Watts to Speed Calculator estimates cycling speed from a rider’s power output using a physics model that accounts for aerodynamic drag, rolling resistance, and road gradient. Users enter their sustained power in watts, select a riding position to determine the drag coefficient (CdA), specify rider and bike weight, choose tire type to set rolling resistance, and input road grade and wind conditions. The tool returns an estimated speed in km/h and includes a power comparison chart for pacing reference. The site also provides a CdA reference guide and explanations of how aerodynamic drag increases with velocity, helping users understand the physics behind the numbers. Compared to other bike speed calculators, Pedal Science’s version stands out for its granular position options—from hoods to aero bars—and its explicit tire/ surface categories that translate into rolling resistance values, offering more practical specificity than generic sliders. It also links directly to educational content on the site, grounding the math in real cycling context.
How to use the Pedal Science Bike Speed Calculator
- 1
Open the Watts to Speed Calculator on Pedal Science and enter your sustained power output in watts.
- 2
Select your riding position from the list (e.g., hands on hoods, in drops, or aero bars) to set the drag coefficient, or enter a custom CdA value.
- 3
Input your rider weight in kg and the total bike + gear weight in kg, then choose the tire/surface type that matches your conditions.
- 4
Enter the road gradient percentage (0 for flat, positive for uphill, negative for downhill) and any headwind or tailwind speed in km/h.
- 5
View the estimated speed result and use the power comparison chart to see how changing position or conditions affects speed at the same power level.
Best for
This tool suits cyclists and commuters who want to estimate their speed from a known power output while fine-tuning for position, weight, and terrain, particularly those preparing for time trials or solo efforts who need to compare pacing o
Limitations
- Results are estimates based on a simplified physics model and may vary with rider fitness, exact bike setup, or exact wind conditions.
- The tool requires the user to know or approximate their sustained power in watts; it does not calculate power from heart rate or perceived e
- Extreme gradients over 3% are noted to require a separate climb-time calculator, and very steep or technical terrain may reduce accuracy.
Bike Speed Calculator FAQ
- Can I use this calculator if I don’t know my exact wattage?
- The calculator estimates speed from power using a physics model that includes aerodynamic drag, rolling resistance, and gradient. It does not factor in drivetrain efficiency losses, rider flexibility, or exact wind gusts, so treat the output as a general guide rather than a precise prediction.
- How does riding position affect the speed estimate?
- The tool provides a CdA reference guide with typical ranges for pro TT position (0.20–0.22 m²), aggressive drops (0.25–0.28 m²), hoods (0.30–0.35 m²), and upright/leisure (0.45–0.55 m²), allowing you to match your actual bike fit to the closest category.
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- 02Cycling Watts Calculatorwattscalculator.com
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