FTP Guided Test too hard, FTP not detected

Hmm... I am puzzled. I have no idea why this stopped working for you. I am left with coming up with things to try:

- delete the sports heart rate zones and keep your Max HR at 192bpm and do a soft reset of the watch, then try again

- if this didn't fix it, I would consider doing a factory reset and backup restore after having deleted the sports heart rate zones

What Garmin does is that it looks at the last sustained 4 min wattage and multiplies it by 0.75. So your FTP should be 265Wx0.75= ~200W. But, based on your workout, that was not the case. The algorithm got confused what has happened in the last 4-8 mins of your test. 

I think you should have stopped pedaling at minute 31, when you couldn't push at 285W. At min 31 in your FTP test, it seems your trainer also came out of erg mode, since you could still pedal, but you were not matching with 285W. Do you think that was the case? Your power hovers around 150W-230W.

Anyway, your test is still valid. You can manually enter this FTP number (200W) in your Garmin connect app. 

I don't think any of that is correct. In the previous FTP guided test that I did several months ago, I sustained 4:00 at 265W but then the test automatically ended at that point and didn't attempt to push me higher. In this most recent test, it pushed up to 285W but I couldn't hold the power and my cadence dropped way down. The trainer didn't come out of erg mode. If the test worked correctly as documented, then it should automatically detect when I hit the threshold. I shouldn't have to just stop pedalling.

My FTP isn't great but it is higher than 200W. It was auto detected at 220W based on random outdoor rides. The funny thing is that when this failed test synced to TrainingPeaks, that system independently analyzed the same FIT file data and updated my FTP to 221W.

nradov said:

I don't think any of that is correct.

Finally we have arrived at a point where I feel it is the time to jump in. No, it is very likely incorrect/inaccurate.

it should be still close  to the previous one, 220W that you had already elaborated. Since 220W was calculated using random outdoor rides, one may assume that some of them included longer strenuous time spans longer than 5-8-10 minutes, and closer to 60 minutes, or at least to 20 mins.  And if you cycle at least on an irregular base, a drop of almost 10% is not very probable. Unless you are much older than your avatar implies it. Because then one year can have a big impact on your data.

nradov said:

The funny thing is that when this failed test synced to TrainingPeaks, that system independently analyzed the same FIT file data and updated my FTP to 221W.

It is really funny, indeed. I am not a .fit file expert, but my intellectual bet is that .fit files contain the actual FTP data, and while Garmin may truncate your previous FTP of 220.xx watt when it displays, TP may round it to the next integer. It would explain it. But of course other explanations do exist also.

I don't think that FIT files contain the actual FTP data. At least the SDK doesn't have any such message defined.

TrainingPeaks has its own algorithm for detecting FTP changes based on the power data in the FIT file.

Power Threshold - Bike or Mountain Bike: We suggest a threshold increase if your 95% of your Average Peak 20 Min Power is greater than your currently set threshold.

How Does TrainingPeaks Calculate My Threshold? – TrainingPeaks Help Center

nradov said:

I don't think that FIT files contain the actual FTP data.

I made some fast check and at first glance it is mentioned very rarely, see eg. here in 2nd para: forums.garmin.com/.../run-ftp-vs-cycling-ftp

And I opened one of my cycling fit files and I found FTP as a data. It was an Edge 530 file, but I am almost sure that F6X also have it.

Use https://www.fitfileviewer.com and you will see it.

Anyway it was just a side thread of thoughts….

Sorry, you are correct. The FIT file does contain FTP in the zones_target 7 message functional_threshold_power 3 field. I was looking in the wrong place.

Edge 1040 here. So I've played with this test quite a bit. I've found that if you wander too much out of the fairly hard to maintain narrow power window at a particular level being asked of you the test will end. As already said it just stops and gives you no indication of anything on the screen but I do find that it has logged a new FTP in the my stats FTP section. As the power levels go up it is of course harder to maintain the narrow power window it's asking for. I suspect the algorithm is just too tight as far as power variability achieved during the test. Most of the issue I feel is finding a consistent test course to attempt to maintain the power level wanted in the test. I gave up on it as it's too hard to get a valid test unless you have a perfect stretch of road to conduct the test. If you do have a great stretch of road I found it's easier to get a good test. But still I've found it much easier to do a 2x8 test or a single 20 min test and analyze it through TrainingPeaks or other software.