Calibrating power meter: TrainerRoad app vs. head unit

Equipment
1

I have a simple and stupid question: Is the zero offset that you obtain from power meter calibration saved in the power meter itself or just in the power meter’s client?

I am asking because I would like to know whether I will have to calibrate twice, once in the TrainerRoad app and then a second time on my head unit. I noticed that the offsets that are displayed are different, too, although they haven’t changed in a year.

2

Saved on power meter I believe so doesn’t matter where you calibrate it.

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3

Correct, setting is stored on the meter. Smart trainers do the same, FYI.

1 Like
4

Awesome, thanks. Follow-up question: why are the displayed offsets different then? They don’t budge, so I reckon everything is hunky dory, but nevertheless, I’d like to know why the offset isn’t the same.

5

I know I’ve seen the answer mentioned, but don’t remember it well enough to state it. I will try a search, but I am nearly certain it’s a non-issue.

Edit to add, this isn’t the exact one I had in mind (still looking), but it is related.

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6

The power numbers seem to be perfectly consistent (my head unit displays a 20-second average of my power, which is helpful on longer intervals), so everything seems to work. But it is just curious: I assumed the offset was a value that’s saved by the power meter. So any app that does a calibration should display the same value, or so I thought :man_shrugging:

I second the feature request, though. That’d be a nice thing to have.

1 Like
7

I think, maybe the offset is saved in the powermeter, and the device used to calibrate it, independently. When reporting power, the powermeter will use the offset that’s saved internally. But there is no sync back to the device to update the offset number, so it could be different.

For example, you use TR to calibrate your power meter, and then immediatly go for an outside ride with your garmin. Your garmin will still show the date and offset of when you last used the garmin to calibrate the PM, but the power numbers coming from the PM are corrected using the new internally stored offset you did with TR just before.

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