Connect Power Curve Issue When Activity is EXACTLY 30min Long

I have an odd issue involving the power curve data in connect.  I use a service to sync my Peloton ride to Garmin.  The ride data is usually EXACTLY 30min (or whatever the corresponding class length was on Peloton).  The problem is that Garmin Connect doesn't recognize the full length. 

Here's an example:  Yesterday I completed a 30min ride wherein I set a personal record for average power over 30min...Yay.  But, when the data was synced into connect, I didn't get any credit for the 30min power record.  In other words, the power curve wasn't updated with my new 30min best.

I looked at the TCX file and confirmed that the time difference between the first and last track points was indeed, exactly, 30min.

To test my theory that the precise time was the issue, I added another trackpoint to the end of the TCX file for additional second.  After uploading this file, voila, the power curves were updated.

To summarize: If I take two identical TCX files, but add an extra second to one of them, then upload them via connect web, the shorter one (exactly 30min) will fail to register a 30min power average. The longer one (30:01) WILL register a 30min power average.  Essentially Garmin Connect is requiring >30min of power data in order to register a 30min power average.

So, how can I get Garmin Connect to actually record the 30min data when the activity is EXACTLY 30min long?

  • It's certainly curious, not inuitively what you'd expect, though it is a bit of an edge case being right on the time mark exactly.

    Just to offer a thought/opinion though, regardless of whether it should work this way or not, I think it's worth keeping in mind what it actually means. Your activity likely has some ramp up/down in intensity at the start/end, all within that 30 minutes. So your avg power output during that time is pulled down by those. Since you want an understanding of your sustained output for any given time period as a measure of your performance, this activity is maybe not the best indicator of your 30-min power --- meaning, you would probably see a higher number if the activity were longer.

    For example if you had a 45-minute activity so that there was a strong 30-minute window within it not affected by ramp up/down at the start/end, then you would probably see a higher 30-minute power level than you do now. So in your case here, the next-lowest value (I think it's at 20 minutes) is probably a much more reliable indicator of your performance when using that specific 30-min workout.

    Remember these time intervals are purely arbitrary, simply to make a graph. Could just as easily use 28 minutes, 22 minutes, etc. The system will use what it has to try to draw a curve for those intervals. But for the result to be a meaningful measure of your achievement, you want to look at a time interval that more closely fits the portion of the activity where you were actually "working", rather than ramp up/down. (Obviously the situation is different for very long endurance activities at lower power levels.)