Cycling Gear Ratio Calculator
Calculate your gear development, speed at any cadence, and compare chainring/cassette combinations to find the optimal gearing for any terrain.
Drivetrain
Physics
How Gear Ratios Work
A gear ratio is the mechanical advantage between your chainring (front) and sprocket (rear):
Gear Ratio = Chainring Teeth / Sprocket Teeth
A 50/17 combination gives a ratio of 2.94 — for every full pedal revolution, the rear wheel turns 2.94 times.
📏 Gear Development (Metres per Pedal Stroke)
Gear development tells you exactly how far you travel with one complete pedal revolution:
Development (m) = (Chainring / Sprocket) × Wheel Circumference (m)
Wheel circumference reference:
| Tyre Size | Circumference |
|---|---|
| 700c × 23mm | 2.096 m |
| 700c × 25mm | 2.105 m |
| 700c × 28mm | 2.136 m |
| 700c × 32mm | 2.155 m |
| 650b × 47mm | 2.149 m |
⚡ Speed at Any Cadence
Speed (km/h) = Development (m) × Cadence (rpm) × 60 / 1000
Example: 50/17, 700×25c, 90 rpm:
- Development = (50/17) × 2.105 = 6.19 m/rev
- Speed = 6.19 × 90 × 60 / 1000 = 33.4 km/h
🏔️ Gearing Strategy by Terrain
Road Racing — Standard Setup
| Terrain | Recommended Gearing | Why |
|---|---|---|
| Flat sprinting | 53×11 | Maximum speed at 100+ rpm |
| Rolling hills | 50×17–21 | Tempo riding, ~30–35 km/h |
| HC climbs (8%+) | 34×28–32 | Sustainable cadence at low speed |
| Steep mountains | 34×34 (compact + 11-34 cassette) | Keeps cadence above 70 rpm |
Gravel / Adventure
- Minimum rear gear: 11-42T or 11-46T cassette with 1× drivetrain
- Recommended front: 38–42T single ring for mixed terrain
🔄 Cadence Science
Optimal cadence varies by rider type: * Road racing: 80–100 rpm (higher cadence reduces muscular stress, increases cardiovascular load) * Time trials: 90–100 rpm (aerodynamic position limits hip mobility at very high cadence) * Climbing: 70–85 rpm (torque efficiency improves at lower cadence on steep grades) * Track/sprint: 110–130+ rpm at peak power output
The 70 rpm Rule: Below 70 rpm, neuromuscular efficiency drops sharply and knee stress increases. If you're grinding below this, you need an easier gear.
📊 Common Road Bike Gear Combinations
| Setup | Lowest Gear | Highest Gear | Use Case |
|---|---|---|---|
| Compact (50/34 + 11-32) | 34×32 | 50×11 | Sportive / gran fondo |
| Standard (53/39 + 11-28) | 39×28 | 53×11 | Road racing |
| Semi-compact (52/36 + 11-30) | 36×30 | 52×11 | All-round racing |
| 1× gravel (40T + 11-42) | 40×42 | 40×11 | Mixed terrain |
Use Cases / Example Scenarios
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These scenarios are illustrative examples based on typical use cases.
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"All formulas and reference values used in this tool are sourced from peer-reviewed scientific literature and validated clinical guidelines. Our research team continuously audits each calculator for accuracy and updates methodology as new evidence emerges."
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