Honestly, for most cyclists, knowing the actual gear inch ratio of every one of your gear combinations is a good recipe for overkill. To the true cycling geek however, you can never have too much information. If you’re one of the latter, take a look at this iGear calculator app for all Apple devices.

iGear is a free app that allows you to input your exact drive train specifications to figure out your exact gear ratios. Whether you’re wanting to build a custom cassette for your road bike, or wanting to see how different chainrings will affect your XX1 drivetrain the app has you covered. There is also an iGear Pro app available for $0.99 that includes the ability to compare two different drive trains on the same screen for the iPad app and more built in cassettes.

Check out the rest of the screen shots after the break.


  1. There are a few “gear ratio” apps on Google Play already but maybe not as polished as this version. “Gear Ratio Calculator Free” is a good place to start but you need the paid version to allow you to add new cogs and cassettes.

  2. Sorry, the database is corrupted. If you wanna add some cassette, you’ll have to erase the database and then add the new one. Temporary fix until I upload a new and corrected version.

  3. It makes me sad that people can’t even calculate gear ratios without an “app”. Gear inches is also a super easy calculation: it is just the diameter of the wheel multiplied by the gear ratio. (Which is really an archaic idea anyway since it would make more sense to multiply by the circumference which would give you the distance traveled with each revolution of the crank).

What do you think?