I am a big fan of Sheldon Brown’s gear calculator page. Sheldon Brown’s gear calculator script allows you to calculate gearing ratios, gear-inches, and speed for given cadences. After using it over the course of several years now, I found myself wanting something that would allow me to adjust the values dynamically and compare multiple different setups at once. I threw together a little app to scratch my itch using Angular.js. Hope this is useful to someone else out there.
Bicycle Gear Calculator