1. What is a Gear Inch Speed Calculator?

Definition: This calculator determines gear inches and bicycle speed based on gear ratio, wheel diameter, cadence, and a constant.

Purpose: It helps cyclists understand their gearing and estimate speed at different cadences.

2. How Does the Calculator Work?

The calculator uses two formulas:

Where:

• \( GI \) — Gear inches
• \( GR \) — Gear ratio (chainring teeth ÷ cog teeth)
• \( WD \) — Wheel diameter (inches)
• \( S \) — Speed (mph)
• \( Cadence \) — Pedaling rate (rpm)
• \( Constant \) — Typically 336 (combines unit conversions)

Explanation: Gear inches represent equivalent wheel diameter of a penny-farthing bicycle. Speed is calculated from how far the bike travels per pedal revolution.

3. Importance of Gear Inch Calculation

Details: Understanding gear inches helps cyclists select appropriate gearing for terrain and maintain efficient pedaling cadence.

4. Using the Calculator

Tips: Enter gear ratio (e.g., 2.5 for 50/20 gearing), wheel diameter (e.g., 27 for 700c wheels), cadence (default 90 rpm), and constant (default 336).

5. Frequently Asked Questions (FAQ)

Q1: What is gear ratio?
A: The ratio of chainring teeth to cog teeth (e.g., 50 tooth chainring with 20 tooth cog = 2.5 ratio).

Q2: How do I measure wheel diameter?
A: Measure from ground to wheel axle and double it when tire is properly inflated under load.

Q3: What's a typical cadence?
A: Most cyclists maintain 80-100 rpm, with 90 rpm being a common default value.

Q4: Why is the constant 336?
A: It combines unit conversions (inches to miles, minutes to hours) and π (pi) for circumference calculations.

Q5: How accurate is the speed calculation?
A: It provides theoretical speed assuming no slip and perfect conditions. Actual speed may vary slightly.