Derailleur 4+

Gear calculator for cyclists

A. H. de Quatre Ltd.

    • Free
    • Offers In-App Purchases

iPhone Screenshots


Winner of the Apple WWDC22 Challenge

--- Trusted by pro teams ---
--- and thousands of cyclists worldwide ---

Derailleur helps cyclists analyze and optimize gearing configurations on their bicycles. Designed to be the best and easiest-to-use app for calculating gear ratios, Derailleur combines precise calculations with an intuitive design, so that changing a bicycle configuration is straightforward.

Derailleur packs powerful features for free like working offline, saving configurations, importing and exporting DRL files, and much more. Intended to cater for all cyclists and modern bicycles, Derailleur offers a wide range of configurations for BMX, MTB, road bikes, fixed gears and track bikes.


• Find a gear that works for you — The gear ratio on your bicycle can be optimized for different terrain, riding styles and fitness levels.

• Discover your cadence sweet spot — There's no right or wrong, everybody's different, riding every day will help you feel what is more natural.

• Measure your top speed — Whether you're looking for comfort or speed, getting to know your bicycle will help you a long way.

• Share with your friends — Export your configurations as DRL files, and share them with most messaging apps.

Derailleur+ combines everything you love about Derailleur, plus even more great features. When you upgrade to Derailleur+ not only will you be able to create an unlimited amount of configurations, but you’ll also get an even greater experience.

Pro Features:

• Create unlimited configurations — If you own multiple bikes, or frequently change configurations, then this one's for you.

All calculations provided are merely for educational and informational purposes. It is not a substitute for professional advice from your local bike shop.

What’s New

Version 3.31.3

Improved performance and squashed bugs.

App Privacy

The developer, A. H. de Quatre Ltd., indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy.

Data Not Linked to You

The following data may be collected but it is not linked to your identity:

  • Purchases
  • Contact Info

Privacy practices may vary, for example, based on the features you use or your age. Learn More

You Might Also Like