There are a few reasons that riders may want to adjust the handlebars of their motorcycle, including comfort and handling. For example, you may want them higher if you’re a taller rider. You can adjust their height with handlebar risers, a component that must be installed if you want to have the ability to adjust the height of your handlebars — otherwise they are secured in place with a clamp. 
You’ll find a variety of options that offer different riding styles and heights. However, changing the handlebar height will drastically impact the motorcycle’s handling since you’ll need to change your seat positioning to better use the bars depending where you settle. 

High handlebars inspire better posture for longer rides, ensuring you don’t slouch like you would with lower bars (although they may lead to wrist discomfort). However, if you increase the height, you will need to sit further back on the bike. This changes the center of gravity, which impacts the handling. While higher handlebars create more stability, the heaviness they create in the front of the bike will make it tougher to turn corners. You will also need more power to propel the bike forward. 

The positioning of your handlebars depends on the type of motorcycle you have and the activities you plan to do with it. If you have a sports bike for tracking or spirited driving, you will want to keep the handlebars low. The lower the bars, the more traction and better the handling at faster speeds due to your lower center of gravity and the weight shifting to the front as you lean forward. Low handlebars reduce drag and improve aerodynamics due to your hunched riding style, letting you be more aggressive. 

Meanwhile, you’ll want to use the handlebar risers to increase handlebar height if you are touring or cruising. This provides additional riding comfort and stability. High handlebars are also beneficial for off-roading, since you want the best control possible — especially if you are going to be standing on footpegs. These riding styles don’t need as much power, making high handlebars more ideal.