Derailleur icon Derailleur download QR code


by A. H. de Quatre Ltd.
iPhone Utilities Requires iOS 16.0


About Derailleur

Winner of the Apple WWDC22 Challenge

--- Trusted by pro teams ---
--- and 5000+ cyclists worldwide ---

Ever wondered how fast you can go on your bicycle? Now you can find out without even leaving the house.

Derailleur lets cyclists quickly and easily estimate their speed at different cadences depending on the setup of their bicycles. Designed to be the best and easiest-to-use app for calculating gear ratios and skid patches, Derailleur combines precise calculations with an intuitive design, so that changing a bicycle setup is quick and simple.


• 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 appropriate top speed — Whether you're looking for comfort or speed, getting to know your bicycle and how to set it right will help you a long way.

• Extend the lifespan of your tyres — If you're a track cyclist you could save on recurring costs by spreading your skid patches evenly around the rear tyre.

• Pick your prefered measurement system — It's never been easier to compare your setup with other cyclists across the world.

• Share your setup with your friends — From a single click, discuss your bicycle setup on the messaging service of your choice.

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