The Stages Bike shift buttons are located on the inside of both brake levers, as well as a secondary set of shift buttons in the drops of the handlebars. The two buttons by default will operate similarly to a road bike, with the buttons on the left side working as larger shifts (big to little chainring) and the shifters on the right performing smaller gear changes. 

SB20 Shifter button arrangement

These functions can be customized in the Stages Cycling app by creating a new virtual setup. For more information on customizing your shift functions, see Custom Button Configuration in the Stages Bike user guide.