How to Compare Power Data? Kickr Core vs Assioma's

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How are you comparing the power?
Actual or smoothing over 3s, 10s or 30s?
If you record an indoor workout using both recording devices, what is the average power for both

  • Workouts
  • Laps/intervals (try longer efforts like 2m, 4m, 8m, etc.)
  • Max power (do an all out effort for 1-2s)

I download the data as a TCX file, then open it in Excel (xml table). I’ll share an example later (I’m not at home currently).

I never look at instant power, and would prefer to look at average power across different averages (3s can get too noisy).

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Attached is the file I mentioned I use to compare my data on a dual recorded workout; with 3s, 10s and 30s smoothing applied.

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I use icTrainer to compare both: 10. FTP-/Performance-Test with two powermeters (Smart Trainer and Bike powermeter) - YouTube

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Did the comparison (see below). Can’t articulate why but this time the delta was closer to 10% (wahoo reading 10% higher). Apparently this tolerance is acceptable so I’ll just have to live with it. Thanks for your input. Re ally appreciate it.

DC Anayzer

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The delta was closer to 10%. You can compare the data here. Seemed like it was closer to 20% when I did my ramp test on Friday. Not sure why. I guess I’ll have to live with it.

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Unless you have a 3rd power meter to do the comparison, you may want to decide which is going to be your dominant Power Meter and use that as your basis for both indoor and outdoor training.

You could use TR’s power match feature. That’s also what I use on my BreakAway App. my Assioma’s reading about +6w higher

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This.

I suggest you use your Assioma’s as your primary power source and use TR’s power match feature. Its what I do with my Assioma’s and my Stages SB20 (and prior to that my Tacx Neo OG - which there was about a 10w different between FWIW).

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If you are using the indoor cycling software www.ictrainer.com (free for one month / later on 1.50 USD per month) you can use your Kickr as one user and parallel your powermeter as a second user to compare both metrics at the same workout.

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Aussie_Rider I assume you have the Kickr v5? Mine was always over my Favero Assioma whereas my v4 matched very closely.

The v4 is within 2 to 3 watts of my Favero Assioma so I can use either PM without issue wheress with the v5 I essentially had two FTPs, one for oudoors and one when using the Kickr v5.

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Bit late to the party. I made a free analysis tool to do this, its quick and easy to use with quite a bit of analysis. Some details on the site of how and what to look for.
Dual record a ride and select the .fit files on the site. No signup required, just casually compare your power files whenever you want :slight_smile:
Compare Power, Cadence, 5 minute Power curve and L/R (if you have it)
https://compare-the-watts.com/
Has an example loaded up so you can have a play first

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Nice, I made an R script to do just this ages ago and always planned to make it into a shiny webapp but this will save me that requirement now.

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Cheers @Ben, was on my todo for a long time too. I broke my collar bone so had some time :face_with_head_bandage:. As expected coding with one hand whilst sedated is more achievable than training under those conditions :stuck_out_tongue_winking_eye:
Hopefully some people find it useful :slight_smile:

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your tool is amazing and hope your are recovering well or are recovered already!

ps. there is one small bug on mobile version, when you pinch zoom the power graph, whole page is zooming, probably zooming the page should be blocked somehow or the zoom should be done with +/-buttons or something line manual entering time range (similar to selecting intervals here)

cheerz and again fast revovery for you :wink:

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Thanks @Lukasz_Pludowski glad you like it. I had largely left mobile support up until now. Can see what you mean regarding the zoom. I will apply a fix soon :slight_smile:

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I’m resurrecting this thread because if i understand the new custom stream functionality I should be able to add a connect IQ data stream and easily compare the raw garmin watts to connect iq watts. Before I go down that rabbit hole and program the script (1st timer) I want to make sure that’s correct.

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That’s right

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I’m close but not quite. Getting the custom chart was easy. Ends up just being a drop down for my new field: Power2.

Now I’m trying to create a Custom Field that shows up in the interval summary. This requires some scripting but I don’t know how to do it. I’ve done some coding so I know the general approach but any time I use this post (https://forum.intervals.icu/t/server-side-data-model-for-scripts/) to help me figure out which keyword to use I get a "ReferenceError: “xxx” is not defined.

I’ve tried the following
CustomItem.Power2
Interval.Power2
ActivityStream.Power2

I’m obviously not understanding how to use custom stream fields. Could someone dumb this down for me?
BTW, it’s easy to get the data I’m looking for (Power meter 1 avg interval vs power meter 2 avg interval) elsewhere in intervals.icu, but I’d like to figure out this coding aspect.

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Delete

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So do you want to calculate the average for your field for each interval? Assuming your custom activity stream has code “Power2”:

{
  let power = icu.streams.Power2
  let tot = 0, c = 0
  for (let i = interval.start_index; i < interval.end_index; i++) {
    let v = power[i]
    if (v) {
      tot += v
      ++c
    }
  }
  c ? tot/c : null
}
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