What is Rate of Rise (RoR) in coffee roasting?

Rate of Rise measures how quickly bean temperature is increasing at any given moment during the roast, expressed in degrees per minute. It gives you a live picture of the roast's momentum - one of the most useful tools for understanding what's actually happening inside the drum, rather than just reacting to temperature readings.

The pattern most associated with well-developed specialty roasts is a declining RoR: starting relatively high after the turning point and decreasing steadily as the roast progresses. That steady deceleration is generally linked to even, thorough development. A sharp RoR crash - where the rate drops suddenly towards zero - is one of the primary causes of baked coffee. A sudden spike at the wrong moment can push the roast too hard, too fast.

Most modern roast logging software - Cropster, Artisan, RoasTime - plots RoR in real time alongside bean temperature. Learning to read that curve, and to anticipate where it's heading rather than just reacting to where it is, is one of the clearest markers of deliberate roasting versus reactive roasting.