Tired of carrying a gear chart to the velodrome every day, or searching the web for one every time you change gears? Then you need a gear calculator on your iPhone and your Apple Watch. Built by track racers for track racers, the Track Gear Calculator supports chainrings from 44 to 70 teeth and cogs from 8 to 20 teeth. It includes a speed/cadence calculator, and can calculate the next gear up or down using only the gears in your track bag. Want a bigger gear or a smaller gear? Track Gear Calculator works in reverse, too: just swipe the gear inches, and youll get a new gear, up or down from where you are, using only the chainrings and cogs you have with you. You can also select from the standard 27" nominal method for calculating gears, or more accurate actual wheel diameters, and you can see results in either Imperial gear inches or Metric development.