A rate of rise (RoR) crash is one of the most common — and most damaging — faults in a coffee roast. It happens when the rate of rise, which should glide gently downward through development, instead plummets sharply, almost always right after first crack. The clock keeps running and the beans keep coloring, but the energy moving into them has collapsed. The result is the canonical roasting defect: a cup that tastes baked, hollow, and unevenly developed.
This guide explains exactly what an RoR crash is, the closely related "flick," why crashes happen, what they do to the cup, and how to fix one before it reaches the grinder.
If you're new to rate of rise itself, start with Rate of Rise in Coffee Roasting, the parent concept behind everything below.
What an RoR Crash Is
Rate of rise is the speed at which bean temperature is climbing, expressed in degrees per minute. Across a healthy roast it follows a predictable shape: it spikes early after charge, settles, and then declines smoothly all the way to drop. A good development phase shows RoR continuing that smooth, gentle glide down — never flat, never negative, just steadily decelerating.
A crash breaks that glide. Instead of easing down by a degree or two per minute, the RoR dives:
- —RoR is gliding down through the high teens entering first crack
- —First crack hits
- —Within 30–60 seconds the RoR plunges — sometimes to single digits, sometimes toward zero
That sudden drop is the crash. On the curve it looks like the rate of rise line falling off a ledge rather than sloping down a hill. The bean temperature curve itself may still be rising, which is why crashes are easy to miss if you only watch the temperature probe and not the derivative.
The crash matters because the development phase, from first crack to drop, is where the coffee builds its final sweetness, body, and clarity. (See What Is First Crack in Coffee Roasting? for why this window is decisive.) If the energy flux collapses exactly when development begins, the beans coast through the most important phase of the roast on almost no heat.
The Flick: Crash Then Re-Rise
The flick is the crash's twin. A crash is a sharp dive; a flick is a dive followed by a rebound. The RoR plunges after first crack, the roaster (or the operator) reacts by adding heat, and the rate of rise climbs back up before drop.
On the curve the flick looks like a check mark: down hard, then back up. It's tempting to read the recovery as a fix, but a flick is usually worse than a clean crash, not better. The bean has now been through two abrupt energy changes during development — a stall followed by a surge — and that whipsaw shows up in the cup as a muddled, disjointed profile. The exterior and interior of the bean develop at different rates, and the roast loses the even, controlled progression that makes a coffee taste finished.
A flick almost always traces back to the same root cause as the crash: too much heat going in before first crack, then a correction that arrives too late and too hard.
Why Crashes Happen
The mechanism is a collision of two events that arrive at the same moment.
1. The bean's exotherm. Around first crack, the chemistry inside the bean shifts. Up to this point the roast is endothermic: the bean is absorbing heat. Near and after first crack, exothermic reactions kick in and the bean starts releasing some of its own energy. This is a normal, expected transition.
2. A heat cut that lands at the wrong time. Many roasters carry aggressive heat into first crack, chasing a fast, high RoR to drive the roast forward. Then, worried about running away into a too-dark roast, they cut the heat sharply right at or just after first crack.
When those two collide — the bean's natural energy release plus a sudden, large reduction in applied heat — the rate of rise has nowhere to go but down, fast. The momentum that was carrying the curve evaporates, and the RoR crashes.
The trap is the timing. The crash isn't caused by the heat cut alone; it's caused by applying too much heat beforehand, which forces a large correction at the worst possible moment. A roast that enters first crack already on a gentle, declining RoR needs only a small adjustment and glides through. A roast that enters first crack hot and accelerating needs a big cut, and a big cut at first crack is what produces a crash.
What a Crash Does to the Cup
A crashed roast produces the defect most often described as baked: flat, dull, papery, and hollow, with the sweetness and acidity stripped out. (See Baked Coffee and the Stalled Roast for the full sensory picture.)
Specifically, a crash tends to produce:
- —Hollowness. A thin, empty mid-palate where body and sweetness should be. The energy needed to build them wasn't present during development.
- —Baked, flat flavors. Cardboard, cereal, or dull-toast notes instead of clean caramelization. The beans spent time in the drum without enough heat flux to drive complete development.
- —Uneven development. Because the energy stalled mid-phase, the bean's surface and core finish at different points, muddying the profile and dulling clarity.
Crucially, none of this shows up reliably in roast color or total time. Two roasts can hit identical drop temperatures and identical development time ratios, yet one cups clean and the other cups baked — the difference is whether the RoR glided or crashed. Time in the drum is necessary but not sufficient; the energy has to keep moving.
How to Fix an RoR Crash
The fix is almost always upstream of where the crash appears. You don't fix a crash at first crack — you prevent it before first crack.
Ease heat earlier, not harder. The goal is to enter first crack already on a gentle, declining RoR so the bean's exotherm doesn't tip you into a dive. Make a smaller, earlier reduction in applied heat during the back half of the Maillard phase instead of one large cut at first crack. The curve should be decelerating into first crack on its own momentum.
Aim for a glide, not a stall. A healthy development RoR keeps falling slowly, say from the low teens down toward single digits across the development window, without ever going flat or negative. If you see the RoR heading for a cliff, you applied too much heat going in.
Make adjustments early and small. Because of thermal lag, a heat change takes time to reach the bean. A correction made at first crack lands 30–60 seconds later — right in the middle of development, where it does the most damage. Move your heat adjustments earlier so they take effect smoothly.
Don't chase a flick. If the RoR has already crashed, slamming heat back in creates the check-mark rebound and a worse cup than the clean crash would have been. A gentle, measured nudge is better than a surge.
Diagnose across batches. A single crash can be bad luck; a crash on every roast of the same bean points to a profile problem, usually heat applied too aggressively before first crack. Logging RoR shape batch over batch is the fastest way to see whether you've fixed the cause or just patched one roast. The companion guide How to Read a Roast Curve walks through spotting the dive on the derivative line.
See It on Your Own Roasts
First Crack flags an RoR crash after first crack automatically on every roast you import. Bring in an Artisan .alog file or log a roast live (no hardware required), and First Crack reads the rate of rise across your curve and pinpoints the dive: for example, "rate of rise dived to 6°F/min around 9:15, 11°F/min below where it sat at first crack," along with the fix to ease heat earlier next time.
It isn't AI guesswork. First Crack assesses each roast on known, measurable axes — rate of rise, development time, and more — and locates the crash on the exact point of the curve where it happened, so you can connect what you saw at the roaster to what you taste in the cup.
See how roast analysis works or start free and import a roast to find out whether your rate of rise is gliding or crashing.
See also: Rate of Rise in Coffee Roasting · What Is First Crack in Coffee Roasting? · Baked Coffee and the Stalled Roast · How to Read a Roast Curve · Development Time Ratio