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20minFTP-test-Inside vs Outside

tim cronktim cronk
in General Training Discussions

Same bike , same PM , 6 weeks apart , inside vs outside.

Today's test    http://www.trainerroad.com/cycling/rides/86718 ;   http://connect.garmin.com/activity/232039603  ; results via TR was NP234/ AP233, TR recommended new FTP of 221 based on results which is 95% of the AP233 .... Interestingly the data off Garmin today said NP235/AP235 and a 95% number of that would have been FTP 223.

6 weeks ago on 8/29 and 10 days after IMMT    http://connect.garmin.com/activity/216503911 ; results were NP 242 and AP 241 which gave me a FTP just under 230 which matched my highest tested  2x20 FTP of the year.

For inside on the trainer I have adjusted my FTP down to 221 as suggested by TR.  For outside and the last two races I have for this year I am keeping my FTP at 230.  I've been able to hit outside numbers based on that while training and also have raced IM @ .73 , HIM @ .95 ,  OLY @ .90 and Sprint above .95 so see no reason to change for outside.  But inside, it is what it is, and that is that.

Looking at the test file from today its obvious I was a little too hot in the first half and faded on the second half.  For me RPE was off the charts and that is reflected in HR.  I have never tested with an avg HR above 172 before  and you can see most of that 20 minutes was 180 or more.  Just crazy hard.

So my take away is this .  My inside FTP is 4-5% lower than outside and pretty happy with that.  20 min test's are not any easier than 2x20 lol but I already knew that!

Questions , comments , or other comparisons are welcome!

Thanks Tim,

Comments

  • tgarsontgarson
    I don't have objective data available right now, but you are of course not alone. The vast majority of people tend to test lower indoors, a very approximate value is ~10W, which pretty closely lines up with your 4-5% figure in this example.

    Likewise, I would agree with your plan to use your indoor FTP for the basis of indoor training but use an outdoor-derived or outdoor modified value for your remaining outdoor work and racing, the necessity to re-test outdoors of course being based on your confidence in the accuracy of your projected outdoor FTP, which I would say seems pretty conservative and safe.

    Only other comment somewhat related to this topic, I also see similar shifts based on position. My road bike FTP is about 10W higher than my tri bike FTP due to position, but of course this power advantage is more than negated by aerodynamic penalty in terms of actual top end speed or efficiency. Conversely, I can manipulate my FTP both indoor and outdoor via position even on the same bike. That is to say, my FTP sitting up on my tri bike will likely be different than my FTP in the aerobars, and as far as racing goes I will always use the value that is most accurate to the conditions in which I intend to race, or plan to apply some sort of modifier if the race conditions differ from my test conditions (heat, bike, position).

    So, sorta anecdotal story on my part, but I ride indoors over the winter on my weekday rides (no daylight after work, not because of temp) on my older road bike. My indoor FTP takes a hit, but I get a little boost in FTP due to the road bike, and as a result, my indoor road bike FTP is a not too far off from my outdoor TT bike FTP based off my experience, has been a somewhat useful observation to me.
  • Joseph LombardiJoseph Lombardi

     It all seems reasonable and good...it will be interesting for me this year...as I will now start to have comparison data to last year both with TrainerRoad and with Powermeter....It will be interesting to see how it all stacks up....I will also be using my roadbike during the OS and on the trainer and outside on weekends......

  • Cary BlancoCary Blanco
    I generally see about 4% less indoors with identical tests (2 x 20 indoors and out).
  • robin sarnerrobin sarner

    Right.    Just starting converting to the 20 minute test.      Trying to compare indoors to outdoors.  Use computrainer but even when recording from my quarq, indoors much lower.    But only have a couple tests to compare.       I would think that quarq recorded data would be the same indoors versus outdoors.   Maybe higher ftp indoors due to lack of distractions.      But I guess most of us find this NOT to be the case.

    Other issue for me is how accurate is the ergo or computer screen power on my comuptrainer versus the quarq.      Numbers seem to be the same in real time.     But NP varies.   Computrainer calculates NP different than quarq through Garmin?

     

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