How to Roast Coffee at Home, Chapter 3: Does faster drum speed produce better coffee? (Part 1)


When our newest green coffee bean from Colombia arrived last week, we decided it was the perfect bean to help us answer the question, "Does faster drum speed produce better coffee?" 

Scroll down to learn more, and contact us if you enjoy the post. 

The Short Answer

Yes, faster drum speed produces better coffee, but the difference was narrower than we expected. Both batches were bright and fruity; the higher-RPM batch had a slightly more complex aroma and taste.

progression of green coffee beans during first crack on a home coffee roaster

That said, we experimented with 12 oz batches. We suspect that the difference may be more pronounced when roasting a larger bean mass. We'll repeat the test with 20 oz batches later this week. If you follow us on social media, we'll let you know when we publish those results. 

Full disclosure: The above graph is illustrative, based on our observation. We didn't count each individal pop with an audiophone. That would be crazy. But also kinda cool.

Here's an overview of the A:B test we ran. For details, check out the Long Answer below.

The Long Answer

Green Coffee Beans: Colombia Huila Monserrate

This bean cups beautifully at multiple roast levels, so we were confident that both batches would taste good...and we were right! If you're new to home roasting and are looking for a forgiving bean that tastes great under a variety of roasts, we recommend this one. 

Home Coffee Roaster: Behmor 2000

A nice feature of the Behmor 2000 is the ability to switch drum speeds from 16 rpm to 32 rpm with the touch of one button, which is precisely what we did here.

If anyone is still home roasting coffee on on the original Behmor 1600 with the 8 rpm motor and no ability to increase the speed, we endorse the upgrade kit to the 16/32 motor. We still have an original Behmor in storage, so we will dig it out soon and experiment on the same bean at all 3 speeds: 8, 16 and 32 rpm. 

But even without a direct, side-by-side taste test, we distinctly recall roasting on that old model produced more-than-a-little-uneven roasts, especially on larger batches.

Batch Size12 oz

A key caveat here is that our first experiment used 12 oz batches. Check back with us later this week when we repeat this experiment with a pair of 20 oz batches.

We predict that the faster batch will be much more even on the larger bean mass, and thus, taste much better. 

Pre-heat/Initial Time AdjustmentNone

If you want to make replicating this experiment as simple as possible, you could press the "minus" button to reduce the starting time to 16:00, since that's the total roast time we ended up doing.

Button Sequence:

Not a whole lot more to say here other than that 16 rpm is the default setting. Pressing "D" (as in "drum") once the roast starts simply toggles between the two speeds during the roast.
  • Batch A: 1, Start, P5 (16 rpm)
  • Batch B: 1, Start, P5, D (32 rpm)

First Crack (1C)4:00 (displayed*), 399 F (bean)

To our surprise, first crack started at the same time and temperature for both batches. We had expected the 32 rpm batch to start cracking a bit sooner than the 16 rpm batch.

What didn't surprise us was that the distribution of the individual "pops" of first crack arrived in a tighter cluster at the higher drum speed (the orange columns below). The blue columns represent the lower drum speed.

faster drum speed led to more complex cup

Above: Illustrative data showing approximate distribution of individual "pop" sounds during first crack of each batch. While both the 16 rpm (blue) and 32 rpm (orange) batches started first crack at the same time, the faster drum speed enabled a more rapid completion of first crack. From there, that batch developed a slightly deeper, more nuanced taste.

*A side note on displayed vs elapsed times...The Behmor counts down from whatever time is displayed before pressing "Start" (i.e. like a timer you would use when preparing any other food), rather than starting at 0:00 and counting up (elapsed time, like a stopwatch at a racetrack). This is a safety feature, which we understand...but oof. We don't like it. Commercial roasters count up from zero, plus it's intuitive to think of more time equaling more temperature and thus, darker roasts. 

We prefer to think in terms of elapsed time. That said, we report both so that no matter how you think about it, it's easy to follow. Hopefully that's useful. (Seriously, if reporting both times confuses rather than helps, contact us and tell us what you think.)

In-flight Adjustments:

If you're looking to repeat our experiment verbatim, here's what we did with both batches (which ended up with a bright, fruity cup). 

  • Power: Press P3 at the beginning of 1C
  • Time: Start cooling cycle with 2:00 displayed

If you'd prefer a medium or dark roast, give it an extra 15-45 seconds, depending on how dark you like your coffee. NOTE: We haven't tried that, but that's our best guess based on experience.

Cooling Method: Open door

While the Behmor is designed to roast with the door closed and trap the chaff, we prefer the crisper taste that we get when we open the door at the start of the cooling cycle. Check out our earlier post on cooling experiments to learn more.

ResultBerries and bright acidity

Both batches tasted remarkably similar, but the faster drum speed had a bit more depth and complexity. It's a classic Colombian flavor profile that's sure to delight.