Primary Measure IBTS or Probe?

Hey I am a new Bullet R1 v2 owner! something that I’ve been wondering is if should I set up the primary measure on IBTS or PROBE?


There are fans on both sides of the choice.

  • B-Temp originates from a probe on the Bullet face plate which is in contact with the beans as they heat and roast.
  • IBTS uses an IR-sensor and measures the IR radiation from the beans as they heat.
  • Additionally the IBTS is what is used to set drum temp during preheat; B-Temp is only used to establish that temp is stable during preheat.
  • IBTS reads higher initially, but near the end of the roast B-Temp value approaches IBTS value (depending on how dark you roast).
  • When he did his studies back at the dawn of time, Maillard was probably not using an IR sensor!

So take your pick. I started using B-Temp since it was what I had on the HotTop… it was a familiar number. Since then I migrated to using IBTS as the primary measurement. But the real principle measurements will continue to be sound (listen for 1C/2C), sight (color) and smell.



I personally use the IBTS for everything up to and including FC. After that, I find the bean probe more useful as I navigate the development phase toward a pre-determined bean probe drop temperature. IBTS temperatures after FC can go up and down leaving me wondering if my final drop temperature is truly the same roast after roast. Bean probe after FC doesn’t seem to have that problem and I feel more confident in my final temperature reading. Also, if using the recipe function where temperatures trigger changes in power or fan speeds, it’s much easier to use Bean Probe temps after FC, as again, they are always on the rise and you can control the ascent to your desired temperature better this way. All other triggers leading up to and including FC are IBTS though.

In the end, just be consistent in your approach. IBTS only, probe only, or hybrid.


I’ve seen the same in the past - IBTS prone to exaggerated swings that made me want to micromanage power because I thought the roast was crashing and I wanted to maintain a Rao-perfect profile.

Don’t know if the sampling/smoothing algorithms have changed in more recent releases but I see less of this now and I’m able to apply just two power drops and get nice profiles on both IBTS and bean probe. But I still tend to monitor bean probe ROR more than IBTS post FC start, for exactly the reason you state.


I still scratch my head over the differences in the two temperatures on the Bullet. I’ve only gotten 6 roasts under my belt now on the R1, but the ITBS temperature much more closely reflects what I’ve been used to seeing for the past 20 years on my Poppery 1.

For all that time, I have used a simple Taylor dial thermometer as my primary measure, with the tip in the center of the bean mass, alongside a SLE (special limits of error) small-bead thermocouple. EVERY time I ever checked the dial against the thermocouple, they matched to within a couple degrees. Even being a dial, it always kept up quite well with the temperature change, not lagging the thermocouple more than a 2°-3°F. I’ve always seen 1st crack begin to happen at 390°-400° F, and 2nd crack starting at 440°-450°F.

That matches very well with the ITBS temps from what I’ve seen so far, and I’m left wondering why the probe temperature is SO far off, and lags so much.

Now that I’m done with oily roasts (going so dark in those seasoning roasts gave me some serious heartburn lol), I will probably give the roaster a good cleaning to remove all that crap, since I never get more than a few snaps into 2nd crack in my normal roasting. I am curious to see the bean probe setup when I remove the face plate…