Bike Gears

Bicycle Gear Calculator for iPhone and iPod Touch

Designed by a cyclist, for cyclists, Bike Gears is the premier Bicycle Gear Calculator for the iPhone/iPod Touch.

Building a new bike from scratch? Test out possible configurations and get it right the first time.

      «Bike Gear Calc rules. A clean interface provides what you need without fluff. Great that tire size is now sticky, and the new tire size selection interface is smart and flexible. The skid patch feature rocks.
      I build and maintain bikes, and app has helped me provide quick answers for riders' "what-if" questions and tailor their rides to their riding. It's a handy tool for all cyclists, from serious mechanics to everyday commuters.»
      — BikeRanger - Version 2.0.1 - 20-Oct-2009

Calculate Gear Ratios, Gear Inches, Development and Gain Ratios using your bike's measurements. The app now has over 200 preset tire sizes and also lets you enter your own custom tire size for personalized measurements.

Find equivalent gearing configurations to reuse components you already have, or even to save weight by using smaller gears!

Want to convert your old hardtail into a single speed? No problem: take a ride on a geared bike to tweak your gear ratio, then calculate the equivalent ratio for your single-speed. Best of all, it doesn't matter if they have different tire sizes!

Enjoy skidding on your fixie? Using the Skid Patch Analyzer, you can visualize your tire's wear spots and choose optimal gearing to maximize your tire longevity!

      «This app is wonderful. It was handy & fun when I first got it, but since entering the fixed gear road and singlespeed mtb world it has become invaluable. Worth every penny.» (★★★★★)
      — Robot Devil - Version 1.2 - 27-May-2009

No more what-ifs, no more guestimating, and most importantly, no more costly mistakes.

Bicycle Gear Calculator is a must-have for bike mechanics, bike builders, BMX riders, alleycat racers, commuters, athletes and coaches alike!


  • Gear Ratio calculator
  • Gain Ratio calculator
  • Gear-inch + Development calculator
  • Skid-Patch visualizer for fixed-gear addicts
  • Gear equivalency tool lets you find equivalent or closest-match gear ratios
  • Speed calculator taking into account cadence and bicycle parameters
  • Supports virtually any bicycle:
    • 20T to 63T Chain Ring
    • 8T to 36T Sprocket
    • 150mm to 200mm crank arms lenghts in 2.5mm increments
    • Now with over 200 tire sizes
    • If you prefer, enter your tire rollout in millimeters or inches.
  • Metric and imperial units


  • English, Français

Take me to the App Store!

Also looking for software to log your rides? Ron Forrester's Cychosis allows you to quickly and easily record all your training rides on any number of bikes using routes you can pre-define. Head over to the iTunes App Store to purchase now!