Analysing three sources of power: file weirdness

I’ve just bought a pair of Favero Assioma Duos, having used Stages LR for the past 12 months. To see how much variance there is between the Assiomos, Stages and my turbo (Cycleops Hammer), I did a ramp test (not to establish my ftp but as a useful workout for covering a fairly wide range of watts).

Using ANT+, I had paired the Hammer to the TR app, the Assiomos (set to cadence only in the TR app) to a Garmin 820, and the Stages to a Garmin 520. The Assiomas and the Stages were calibrated before starting the workout, the Hammer 10 minutes into it.

I uploaded the three data files to DC Rainmaker’s analyser tool:

I’m baffled why the data from the Stages and Assiomas overlays each other in the graphs but the Hammer’s data only appears after around 14 minutes. I pressed start on the two Garmins as soon as the workout started in the TR app. According to the data uploaded to TR (which correctly shows the Hammer as the power source), the workout lasted 23 mins 8 secs.

I don’t understand why the data uploaded from all three devices to the analyser tool shows the workout in two distinct parts: the Stages and Assiomas for the first part and the Hammer for the second.

Any ideas anyone? Please don’t tell me it’s something really obvious :joy::joy::joy:

Two ideas:

  • Are the timezones correctly set for all of the recording devices?
  • Ask DC Rainmaker, as this is his tool

I fear that DCR might be the only one who can answer your question.

But even if you got the starts to line up, you’re going to have a problem because the TR data from the Hammer auto-paused and missed out the period where you weren’t pedalling, so the Hammer file won’t match the other two after that point. In fact is it possible this may be the root of the problem because the tool was struggling to line up the data?

Either way, I’d repeat the test, except this time don’t pause in the middle of it.

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Have you looked at each of the files individually? Eg on TR, TP, or Strava`?

Under the .fit file that is off, you can +/- seconds so all your graphs line up time wise. I also suggest using 10 second smoothing if you want to compare all three.

DCR Analyzer uses time stamps to align files, so I’d assume one unit is off.

I suspect you’re right Martin. I did wonder if calibrating the Hammer after 10 minutes had something to do with it. Only one thing for it: repeat the test with no pauses.