Rate of Rise

Rate of Rise, commonly abbreviated as RoR, is arguably the most important metric in modern coffee roasting. It measures the derivative of bean temperature over time, essentially telling the roaster how fast the beans are heating up at any given second. While the bean temperature curve shows you where you are, the RoR shows you where you are going.

What is the ideal RoR? Most experts, including Scott Rao, advocate for a 'continually decreasing' RoR throughout the roast. This means that while the beans are always getting hotter, the speed at which they gain heat should gradually slow down as the roast progresses. A sudden spike in RoR can lead to scorching or tipping, while a sudden crash—where the RoR drops too quickly—can result in a 'baked' coffee that lacks acidity and sweetness.

RoR is typically displayed on roasting software as a secondary line on the roast profile graph. Roasters use this data to make real-time adjustments to gas pressure and airflow. For example, if the RoR is dropping too fast as the coffee approaches first crack, a roaster might increase the heat to maintain momentum. Conversely, if the RoR is too high, they might reduce the heat to prevent the roast from finishing too quickly or unevenly.

In practice, understanding RoR allows for incredible consistency. It is the difference between a roaster who relies on intuition and one who relies on data. For the coffee drinker, a well-managed RoR ensures that the chemical reactions—such as the Maillard reaction and caramelization—have sufficient time to occur, resulting in a balanced, flavorful cup. When you see a roaster talking about 'smoothing the RoR,' they are working to ensure that the heat application is gentle and controlled, which is a hallmark of high-quality specialty coffee.