This handy and easy to use app enables you to calculate thegearratio, in standard gear inches, for any given chainring,rearsprocket, and rear wheel and tyre size combinations. It alsoletsyou see which other chainring and sprocket size combinationscomeclosest for all the different chainring sizes listed (20T to49T),making comparisons of different set ups a piece of cake andgivingyou valuable insight into the impact ofdifferentconfigurations.