Simply enter any sprocket or chainring size from as little as 1 sprocket and 1 chainring up to 12 sprockets and 3 chainrings, select a common tyre size from the drop down list of over 150 tyre sizes and select what result you want.

* Calculations options are: Roll Out in metres, Roll Out in inches, Skid Patches, Gear Inches, km/h, mph, Ratio and Gain Ratio

* Adjustable cadence from 60 to 120 rpm for speed calculations

* Database of over 150 tyre sizes

* Entered C/rings and sprockets are automatically saved

* Option to share your calculation by email or your preferred messaging app, mechanics share your recommended gearing with your customers