Calculate Your Bike Gearing
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Gear Ratios & Speed Table
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Popular Setups 2025
Gear Ratio Guide
Climbing Gear Check
Complete Guide to Bike Gearing
Understanding Gear Ratios
Your bike's gear ratio determines how far you travel with each pedal revolution. It's calculated by dividing the number of teeth on your chainring by the number of teeth on your cassette cog. A higher ratio means you'll go faster but need more power, while a lower ratio makes pedaling easier but reduces speed.
Quick Formula
Gear Ratio = Chainring Teeth ÷ Cassette Teeth
Speed (mph) = Gear Ratio × Wheel Circumference × Cadence × 0.00595
Choosing the Right Gearing for Your Riding
Road Cycling Gearing
Modern road bikes typically use either compact (50/34), semi-compact (52/36), or standard (53/39) chainrings. The choice depends on your fitness level and terrain:
- Compact (50/34): Best for recreational riders and hilly terrain. Provides excellent climbing gears.
- Semi-Compact (52/36): Balanced option for fit riders who want both climbing ability and top-end speed.
- Standard (53/39): For racers and strong riders on flatter terrain.
Gravel and Adventure Gearing
Gravel bikes need wider gear ranges for varied terrain. Popular options include:
- 2x Systems: 46/30 or 48/31 with 11-34 or 11-36 cassette
- 1x Systems: 40-44T chainring with 10-42 or 10-50 cassette
- Gear Range: Aim for 400-500% total range for versatility
Common Gearing Mistakes to Avoid
- Too high gearing: Many riders choose gears that are too hard, leading to knee problems and poor climbing.
- Ignoring cadence: Optimal cadence is 80-100 rpm. Gearing should support this.
- Cross-chaining: Avoid big-big and small-small combinations which wear components.
- Not considering terrain: Match your gearing to where you actually ride, not theoretical needs.
1x vs 2x vs 3x Drivetrains
| System | Range | Weight | Simplicity | Best For |
|---|---|---|---|---|
| 1x (Single) | 400-520% | Lightest | Simplest | Gravel, MTB, CX |
| 2x (Double) | 400-550% | Medium | Moderate | Road, Gravel |
| 3x (Triple) | 550-630% | Heaviest | Complex | Touring, Casual |
How to Calculate Your Ideal Climbing Gear
To determine your ideal climbing gear, consider these factors:
Climbing Gear Formula
- 1. Determine your sustainable climbing power (typically 70-80% FTP)
- 2. Calculate speed on target gradient using: Speed = Power / (Weight × Grade × 2.7)
- 3. Find gear ratio needed: Ratio = Speed / (Cadence × Wheel Circumference × 0.00595)
- 4. Choose cassette/chainring combination that provides this ratio or lower
Gear Inches and Development
Gear inches and meters development are alternative ways to express gearing:
- Gear Inches: (Chainring ÷ Cassette) × Wheel Diameter in inches
- Meters Development: Distance traveled per pedal revolution in meters
Typical Ranges
- • Touring low gear: 20-25 gear inches
- • Road climbing: 30-40 gear inches
- • Flat cruising: 70-90 gear inches
- • Sprint/descent: 100-125 gear inches
Frequently Asked Questions
What is a good gear ratio for climbing?
A good climbing gear ratio is 1.0 or lower. For steep climbs, aim for 0.8-0.9 (like 34/34 or 32/36). Professional climbers often use 36/32 (1.13) as their lowest gear.
How do I calculate bike gear ratios?
Gear ratio = number of teeth on chainring ÷ number of teeth on cassette cog. For example, 50/11 = 4.55 gear ratio. Higher ratios mean harder gears for speed, lower ratios mean easier gears for climbing.
What gear inches do I need for touring?
For touring, aim for 20-25 gear inches as your lowest gear (for loaded climbing) and 100-110 gear inches as your highest (for descents). This typically requires a wide-range cassette like 11-42 or 11-46.
What's the difference between 11-28 and 11-32 cassette?
An 11-32 cassette provides a 14% easier climbing gear than 11-28. With a 50/34 crankset, the 34/32 combination gives a 1.06 ratio vs 1.21 with 34/28, making steep climbs significantly more manageable.
How fast is 90 rpm in each gear?
At 90 rpm with 700x25c tires: 50/11 = 38.5 mph, 50/15 = 28.2 mph, 34/28 = 10.3 mph. Use our calculator above to find exact speeds for your specific gearing and tire size.