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Bug in power recording!!

Tecamach
over 5 years ago

Hi everyone,

When I Zwift, I record every time one with my 945 and the other with the laptop.

After some test with an Xcadey XpowerS, I found some quirk in the max power recorded from the watch.

So, Long story short, the 945 is recording 3/4% less in the max power as you can see there:

https://www.zwiftpower.com/analysis.php?set_id=26675

That one is the same output (DiretoX) recorded once from zwift "2020-04-21-17-55-14" and the other with the 945 "4817204174".

How is that possible? I have also 1 second recording in the 945.

  • 0 over 5 years ago

    What is sending the power data? Is it the same source to the watch and to Zwift?

  • 0 over 5 years ago in reply to Dr Phil

    Yes, is an Elite DiretoX, same source, same ride.

  • 0 over 5 years ago

    As long as it's consistently different I wouldn't worry about. It's likely down to differences in the way Zwfit and the watch process that received data.

    Question is which one is true? I'm guessing you prefer the Zwift data because it's 3 to 4% higher ;-) but that could be the one that is wrong.

    It's not necessarily a bug with the watch.

  • 0 over 5 years ago

    short BLT or ANT+ Droputs could happen everytime, what says https://zwiftalizer.com/

    your Device Timestamp for Zwift is strange: 2015/01/06 22:08

    i think you always will have a time offset because you can't start recording on both system to exactly the same time

  • 0 over 5 years ago in reply to f|33tStA

    Sorry but your point is partial correct, you have to adjust the time axis accordingly, as simple as that,  they are perfectly aligned each other, because there is this possibility in zwtpower.

  • +1 over 5 years ago in reply to Tecamach

    it was only an idea, didn't know that you can adjust the time axis, anyway a short timeout on ATN+ or BLT could be possible,

    the other thing, i upload my Garmin trainings to Training peaks and often there is a little difference, because Training Peaks interpret the data a little bit different as Garmin himself.

    example:

    in Garmin i ride 10:07 minutes in Power Zone 5 and in Training Peaks it show me with exactly the same zones configure a time of 10:50

    As i understand, the fit files have more details in it, it depends how the backend use this data?

    or look on this, could be possible too, or?

    Why Is There A Difference In My Data Between Garmin Connect And TrainingPeaks?

    Check to see if you have smart-recording or auto pause turned on.  TrainingPeaks is not compatible with Smart Recording or auto-pause, as TrainingPeaks uses every second of raw data when calculating.  For the most accurate data we recommend using every-second recording and turning off auto pause.

    By default, most Garmin devices have Non-Zero Averaging turned on.  This setting throws out all the zeroes when figuring Average and Normalized power.  TrainingPeaks does not throw zeroes out because time spent coasting is resting, and rest allows you to hold a higher average power when you are pedaling.

    https://help.trainingpeaks.com/hc/en-us/articles/204070234-Why-is-there-a-difference-in-my-data-between-Garmin-Connect-and-TrainingPeaks-




    What Is The Difference Between Every Second And Smart Recording?

    From the Garmin website:

    "Some of Garmin's Fitness devices offer the choice of Smart Recording or Every Second Recording.

    Smart Recording records key points where the fitness device changes direction, speed, heart rate or elevation. This recording type allows the user extended recording time given that it is recording less data points, thus taking up less memory.

    Every Second Recording records the activities information every second no matter if the device changes direction, speed, heart rate or elevation. This recording type provides a more defined data log of your activity. However, recording time will be reduced given that it taking up more memory.

    What does this mean when you upload your workout file to TrainingPeaks?

    When there are too many gaps between recorded data points, TrainingPeaks is unable to fully populate workout data from graphs to route maps.  If you are seeing gaps in your workout graph and/or an inaccurate route map for your workout, check to see if you have Smart Recording turned on.  Turn it off if it is on and see if this resolves your issues. 

    https://help.trainingpeaks.com/hc/en-us/articles/204070064-What-is-the-difference-between-every-second-and-smart-recording-

  • 0 over 5 years ago in reply to f|33tStA

    I understand, 

    In my opinion the watch can't refresh the recording data file with enough speed, so it record only a medium value from two point.

    Anyway what I learned is that to compare data from two power meter you need the same recording tool.

    As someone say "this is the  way" :-)

  • 0 over 5 years ago in reply to Tecamach

    yes and every powermeter is different, my Vector 3 are often 10 Watt higher then the powermeter included in my Tacx Neo2 because they measure on different position.