Can you put gears on a dirt jumper bike?

Dirt jumper bikes are specifically designed for dirt jumping, a type of mountain biking that involves jumping off and onto elevated obstacles. Because this discipline doesn't require climbing steep hills, dirt jumper bikes are typically made as simple and lightweight as possible to make it easier to perform various tricks in the air. Therefore, most professional-level dirt jump bikes come without gears and most manufacturers do not offer geared dirt jumpers from the factory. They usually only have a single-speed drivetrain, also known as a "singlespeed" setup, consisting of just the front chainring and the rear cog—this also eliminates unnecessary drivetrain components, further saving weight. However, entry-level or more downhill-oriented models of dirt jump bikes could technically be adapted, or even originally sold, with the ability to use a multi-speed setup.