Understanding your bike’s gear ratio is crucial for optimizing your cycling performance, whether you’re tackling steep hills, cruising on flat roads, or navigating challenging terrains. Sheldon Brown’s Derailer Gear/Internal-Gear Calculator is a powerful tool designed to help you precisely calculate these ratios, ensuring you always have the right gear for any situation. This comprehensive calculator, a favorite among cyclists worldwide, simplifies the complexities of bicycle gearing, making it accessible for both seasoned riders and beginners.
Decoding Bike Gear Ratios: Why They Matter
Before diving into the calculator, let’s understand what bike gear ratios are and why they are so important. A bike gear ratio is essentially the number of times your rear wheel turns for every rotation of your pedals. This ratio is determined by the number of teeth on your chainrings (front gears) and sprockets (rear gears).
- Lower Gear Ratios (e.g., 1:1 or lower): These are easier gears, ideal for climbing hills or riding in strong headwinds. They require less force to pedal but result in fewer wheel rotations per pedal stroke.
- Higher Gear Ratios (e.g., 3:1 or higher): These are harder gears, perfect for flat roads or downhill sections where you want to cover more distance with each pedal stroke. They require more force to pedal but result in more wheel rotations per pedal stroke.
Choosing the right gear ratio impacts your:
- Cadence: The rate at which you pedal.
- Speed: How fast you can travel.
- Effort: How much energy you expend.
- Knee Health: Using appropriate gears reduces strain on your knees.
Sheldon Brown’s Bike Gear Ratio Calculator: A Comprehensive Tool
Sheldon Brown, a legendary figure in the cycling world, created this invaluable calculator to simplify gear ratio calculations for all types of bikes, including those with derailleur gears and internal gear hubs. This tool goes beyond simple calculations, offering insights into gain ratios, gear inches, and meters of development, providing a holistic view of your bike’s gearing.
The calculator is remarkably versatile and allows you to input data for:
- Chainrings: Specify the number of teeth on your front chainrings. You need to enter at least one chainring to use the calculator.
- Sprockets: Enter the number of teeth on your rear sprockets. For derailleur systems, you can either manually input each sprocket or choose from a list of stock cassettes for convenience.
- Internal Gear Hubs: If your bike uses an internal gear hub, the calculator offers an extensive list of hubs from various manufacturers like Sturmey-Archer, Sachs/SRAM, and more, dating back to early 20th-century models. This feature is incredibly useful for vintage bike enthusiasts or those using modern internally geared bikes.
Using the Calculator: Step-by-Step
- Access the Calculator: The Sheldon Brown’s Derailer Gear/Internal-Gear Calculator is readily available online.
- Input Your Data:
- Chainrings: Enter the number of teeth for each of your front chainrings.
- Sprockets or Cassette:
- For Derailleur Gears: Choose a stock cassette from the dropdown menu or enter custom sprocket teeth counts.
- For Internal Gear Hubs: Select your hub manufacturer and model from the provided lists.
- Calculate: Click the “calculate” button.
- View Results: The calculator generates two output pages:
- Full-size Page: Displays detailed gear ratio information.
- Small Page: A printer-friendly, compact version ideal for taking with you on rides.
Understanding the Output
The calculator provides a wealth of information, including:
- Gear Ratios: Calculated for each gear combination.
- Gain Ratios: A measure of how far your bike travels for each pedal rotation, considering wheel diameter. Learn more about Gain Ratios.
- Gear Inches: A traditional unit for expressing gear ratios, relating to the diameter of a direct-drive wheel. Explore Gear Inches further.
- Meters Development: The distance traveled in meters for one pedal revolution, providing a metric perspective. Understand Meters Development.
- Percentage Difference: Shows the percentage difference between each gear, helping you understand the jumps between gears. Learn about Gear Percentages.
Advanced Features and Considerations
- Custom Cassettes: For those building custom cassettes or using less common models, the calculator allows manual entry of sprocket teeth.
- Internal Gear Hub Variety: The extensive database of internal gear hubs, including older and less common models, makes this calculator a unique resource.
- Schlumpf Drives: If you use a Schlumpf Drive with an internal gear hub, the calculator accommodates this setup. You’ll need to input adjusted chainring teeth counts based on your Schlumpf Drive’s ratio (Mountain Drive, Speed Drive, High Speed Drive).
Beyond Sheldon Brown’s Calculator: Exploring Other Resources
While Sheldon Brown’s calculator is incredibly comprehensive, several other excellent resources and calculators are available for deeper analysis:
- Mike Sherman’s Gear Calculator: For RPM range vs. speed calculations. Access Mike Sherman’s Gear Calculator.
- HPV Drivetrain Analyzer (Jake Odell): A more elaborate calculator with speed and cadence data. Visit HPV Drivetrain Analyzer (via Wayback Machine). (Note: functionality may be limited on the archived page)
- Rabbit, A Singlespeed and Fixed-gear Calculator (Tom Kunicki): Specifically designed for fixed-gear and singlespeed riders. Explore Rabbit Calculator.
- “Drive ratios of bicycle hub gears” (John Allen): Provides exact, fractional ratios for hub gears. See John Allen’s Hub Gear Ratios.
Optimize Your Ride Today
Sheldon Brown’s Bike Gear Ratio Calculator is an indispensable tool for any cyclist seeking to understand and optimize their bike’s gearing. Whether you’re fine-tuning your derailleur setup or exploring the intricacies of internal gear hubs, this calculator provides the precise data you need to make informed decisions. Experiment with different gear combinations, explore the impact on gain ratios and gear inches, and unlock your perfect ride today!
Copyright © 1998, 2008 Sheldon Brown
Harris Cyclery Home Page
