Table of Contents
Cadence and Speed Relationship
Your cycling speed is determined by three factors: cadence (how fast you pedal), gear ratio (how your chainring and cog sizes relate), and wheel circumference (how far the wheel travels per revolution). By adjusting any of these variables, you can calculate the resulting speed or find the required cadence for a target speed.
Understanding this relationship is crucial for race planning, gear selection, and optimizing your cycling efficiency. For example, if you want to maintain 20 mph on a flat road, you can determine exactly what cadence you need in each gear combination.
Speed Calculation Formula
Speed by Cadence and Gear Ratio
| Gear Ratio | 70 RPM | 80 RPM | 90 RPM | 100 RPM |
|---|---|---|---|---|
| 2.0 (39/19) | 10.6 mph | 12.1 mph | 13.6 mph | 15.1 mph |
| 2.5 (50/20) | 13.2 mph | 15.1 mph | 17.0 mph | 18.9 mph |
| 2.94 (50/17) | 15.6 mph | 17.8 mph | 20.0 mph | 22.2 mph |
| 3.57 (50/14) | 18.9 mph | 21.6 mph | 24.3 mph | 27.0 mph |
Optimizing Your Setup
- Choose gear combinations that let you maintain 80-95 RPM at your target speed.
- Compact cranks (50/34) offer wider gear ranges for varied terrain.
- Wider cassettes (11-32 or 11-34) provide easier climbing gears without sacrificing top speed.
- Track your preferred cadence across different speeds to optimize gear selection for racing.
Frequently Asked Questions
What cadence do I need for 20 mph?
With a standard 50/17 gear combination and 700x25c tires, you need approximately 90 RPM to ride at 20 mph. This is a comfortable cadence for most trained cyclists and represents a common training pace.
Does cadence affect power output?
Power output equals torque times cadence. You can produce the same power at different cadences by adjusting the force per pedal stroke. Higher cadence with lower force is generally more sustainable for long efforts, while lower cadence with higher force produces more muscle fatigue but may feel stronger for short efforts.