Calibration/offset values varying a lot vs Garmin

Hi guys… I’m curious about the calibration functionality. I have a power2max NGeco connecting to an iPad via bluetooth and a Garmin 500 via ant. Trainerroad reports my battery power as good.

When I calibrate using Trainer Road (iOS), I get a value that ranges between 650 and 1100 or so. If I click calibrate back to back, it’s not uncommon for the numbers to jump within that range.

When I calibrate using the Garmin, I get a value of around 41. If I calibrate back to back, it stays at 41. It changes a little as expected based on temperature.

Any ideas on what is happening (and If I should care?). I’m not worried about the numbers being different (I assume the scale is different), but it’s weird that from one second to another, the Trainer Road value swings 400 up or down.

When calibrating devices, the numbers that show up do not have any significance ( I don’t even know what they mean…). As long as the calibration is successful, you will be getting the most accurate power during your workouts. :slight_smile:

@conorthinks - for what its worth, Stages reports a consistent number between TR, Garmin 520, and Stages app (its usually around 885 for mine).

Hard to say whats going on with your power2max and TR.

I can’t speak for the new P2M but I’ve got a P2M classic and a P2M Type S and the variation in calibration number is at most 10-12 dependent on temperature indoors.

I’d contact P2M to check whether this is expected behaviour of the Unit. The type S returns a number between 986 and 998 and the Classic 690-700

Okay, thanks guys. I tested this again last night and TrainerRoad’s calibration seemed to be more stable (+/- 100), though not as stable as your type S

Weird that TrainerRoad and Garmin display vastly different values. i.e. 750 TR, vs 41 Garmin. I’ll check for Garmin and P2Max firmware updates again.


just realized the same with 2 NGEco units.

when I connect my phone via ANT+ I get a totally different calibration offset as when I connect and calibrate via Bluetooth. both of each (either BLE or ANT+ are consistent within their range). still odd, that you’d get 2 different values.

*edit: the Bluetooh calibration values vary quite a lot, whereas ANT+ is consistent

anyone figured out why this is happening?


I’m curious of there’s been any updates on this. I’m seeing the same behavior when calibrating in trainer road. The ng eco is connected via Bluetooth to my iPhone. The trainer road app returns seemingly random values one after another, 456, 1078, 642 etc.

If I calibrate manually using the p2m app, I’ll get very consistent numbers: -85, -85, -85. I’m wondering what value the trainer road app is actually showing. It doesn’t give me warm and fuzzy feelings that the calibration is working correctly.

As long as your calibration is successful, that’s all you need. :v:

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