Once a source of "Not all you want to know about Texas Adventure Racing," but now just some "leisure" adventure through the eyes of "The K-SPoT"

Monday, February 22, 2016

Stages Power Meter Comparison Part Deux!

Alright, fresh off of a 3rd agonizing FTP test that I am actually satisfied with...short story is, the last two tests were painful--1st one I went out too hard too early and the 2nd one I suspected that something was off with the Computrainer. To show that I wasn't just whining on that 2nd disastrous test, I have comparison plots for that "bad" 2nd test and my latest "good" 3rd test. First the bad:

Click on the image for a better look. There is a lot of data plotted here so I want you to focus on the solid blue and dashed red lines. You can see that the Stages power meter (red dashed) predicts a higher power output than the Computrainer (blue) of about 50 watts at any given time during the 20 minute test. And, yes, I calibrated my power meter. As soon as I started, I knew something felt wrong because, yes, it was hard, but too hard considering I was mashing and the Computrainer was telling me I was "only" putting out barely 250 watts during the beginning. As you can see, I gave up at about the 3 minute mark, shifting to an easier gear. If the Stages power meter was correct (which I think it was), I was putting out over 300 watts during that time period--I wasn't going to be able to sustain that for 20 minutes even if I decided to enter a very, very, dark place. Another telltale is that for the first minute I was trying to lift my pace since Computrainer was saying I wasn't working hard enough, but the power seemed to keep constant at around 245-ish watts. On the other hand, Stages was showing that I was indeed lifting my effort steadily from about 300 to 325 watts.

Now the good:

Same idea here, but totally different result! Look how magical the plot is--Computrainer and Stages data are almost on top of each other! In fact, towards the end they almost look identical in a mean average sense. Not sure it is because either Computrainer or Stages corrected due to "warm up" or if it was an anomaly due to my erratic surging while approaching puke mode. This tells me that the Stages and Computrainer can be expected to match each other if all is good with calibration, warm up, etc. Yay data!!

I do have other interesting plots of heart rate and speed that seem to support my armchair-ing above, but I am done nerding out this time around. Yes, I know, HTFU...but there is such a thing as smart HTFU-ing...I think...


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