It was raining today so I thought -with 'winterseason' in the back of my mind- why not do a small FTP test on the hometrainer (Kurt Kinetic). I use Trainerroad for my hometrainer workouts. Trainerroad is just great. An enormous database of workouts and all can be related to powerzones. I pay only 89 dollar per YEAR! For that amount of money I am not going to invest in a hometrainer on which watts are measured.
I use virtual power in Trainerroad. This basically means that from the speed / resistance relation of the specific hometrainer a power number is calculated. Is this ideal? No. Because the power number calculated is dependent on multiple factors of which 'how tight the tire is pressed to the roller' is a very important one. Also during the ride because of heating up of the tire this pressure changes and thus the powernumber. Basically it should be calibrated during the ride to correct for this.
Then why do I use it? Because it is better than heart rate (especially indoor). Because there is no wind inside to cool one off, your body does not have such a good opportunity to cool down. Heart rate just goes up and at the same time (when you hold your heart rate constant) you can be sure your power also decreases (aka decoupling). More on decoupling on Joe Friel's site:
http://www.trainingbible.com/joesblog/2009/11/aerobic-base-ride.html
I wanted to show you what the decoupling was for my ride on the trainer (which is shown in Trainingpeaks), but my heart rate monitor went everywhere (I think it's time for a battery replacement).
So, do I care much about how high my FTP is on the trainer? No. I only use it as a guide to base my workouts on and every now and then I do a new test to see whether I have improved. However, I then have to make sure that conditions are the same, i.e. the pressure of the tire on the roller is the same everytime. So, tire pressure also needs to be the same. I always check that. Will it always be 100%? No, probably 98% on average since the tire quality goes down after a few rides (so I have to put a little bit more pressure by putting the roller a little bit upward). Bottom line: always make sure that factors which can influence your workouts and monitoring improvement are constant!!
My average power on the roller was 300 on the 20 minute test, and by using the 95% correction factor for an hour FTP comes at 285.
Now. A year ago this FTP number was 323. How about that big difference? It has a bit to do with my form at the moment, but a lot more with the tire-roller pressure which was much lower last year. Also the tire I use now is different from the one I used last year.
A nice feature of Trainerroad is a.o. that you can export your datafile. I always export it and load it to Trainingpeaks. I use the download from Training Device and I drag and drop the Trainerroad file (.tcx) in the box. Simple as that.
Since my current set outdoor FTP (290) is almost the same as my indoor FTP (285) I do not care much about the small difference in calculated TSS, etc scores. When these start to drift more apart I have to change FTP in Trainingpeaks based on whether I ride more indoors or outdoors.
By the way, for a lot of people FTP is lower on the trainer than outdoors. It basically has to do with a lot of energy wasted by the body heating up. That energy is not put into the pedals. Some people use fans to keep it cool.
With all this said and done, the indoor season can start for me :)
To end this post here's the summary:
1h00m, IF 0.93, AP 240, NP 268, TSS 86
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