Bike Power Speed Calculator

Bike Speed Formula:

\[ S = \left(\frac{P}{W \times g \times (RR + GR + DR)}\right)^{1/3} \times \text{constants} \]

Power (P):

watts

Total Weight (W):

Rolling Resistance (RR):

Grade Resistance (GR):

Drag Resistance (DR):

Estimated Speed (km/h):

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1. What is a Bike Power Speed Calculator?

Definition: This calculator estimates cycling speed based on power output, total weight, and various resistance factors.

Purpose: It helps cyclists and coaches understand the relationship between power output and speed under different conditions.

2. How Does the Calculator Work?

The calculator uses a simplified version of the formula:

\[ S = \left(\frac{P}{W \times g \times (RR + GR + DR)}\right)^{1/3} \times \text{constants} \]

Where:

\( S \) — Speed (km/h)
\( P \) — Power output (watts)
\( W \) — Total weight (rider + bike, kg)
\( g \) — Gravity (9.81 m/s²)
\( RR \) — Rolling resistance coefficient
\( GR \) — Grade resistance coefficient
\( DR \) — Drag resistance coefficient

Explanation: The formula balances power input against the sum of all resistances to estimate speed.

3. Importance of Power-Speed Calculation

Details: Understanding this relationship helps in training planning, equipment selection, and race strategy.

4. Using the Calculator

Tips: Enter power in watts, total weight in kg, and resistance coefficients. Default values are provided for typical road cycling conditions.

5. Frequently Asked Questions (FAQ)

Q1: How accurate is this simplified formula?
A: It provides a reasonable estimate but doesn't account for all factors like wind or exact aerodynamics.

Q2: What's a typical rolling resistance value?
A: About 0.004 for road tires on smooth pavement, higher for rough surfaces or MTB tires.

Q3: How do I determine grade resistance?
A: GR = tan(θ) where θ is the angle of incline (approximately equal to slope %/100 for small angles).

Q4: Why is drag resistance typically small?
A: At lower speeds, drag is less significant compared to rolling and grade resistance.

Q5: Can I use this for e-bike calculations?
A: Yes, just include both human and motor power in the power input.