FTP - spin bike vs. outdoors

CanyonBiker
CanyonBiker Posts: 14
edited June 2018 in Road general
According to my 20 minute average on my Garmin via vector 3 pedals, my ftp is around 265. However, I really struggle to maintain 220 watts over the course of a 45 minute spin class on a stages indoor cycling bike, which has a left sided power meter. My right leg is definitely a bit stronger but does this make sense? Just feels like too large of a variance...

Thanks.

Comments

  • stueys
    stueys Posts: 1,332
    Comparing one sided pm’s to full pm’s Is always a bit dodge. Just coupled with comparing indoors and outdoors mean you’ll likely to get a difference (most of us can push harder outdoors unless we do a lot of indoor training).
  • cougie
    cougie Posts: 22,512
    It'll be hotter indoors. Your body can't perform at the highest level of its struggling with the heat.
  • wongataa
    wongataa Posts: 1,001
    In addition to the previous comments calculating your hour power from a 20 minute test is a bit of a fudge. It is perfectly possible that you can't sustain your 20min FTP power for 45 minutes.
  • benjamess
    benjamess Posts: 159
    CanyonBiker wrote:
    According to my 20 minute average on my Garmin via vector 3 pedals, my ftp is around 265. However, I really struggle to maintain 220 watts over the course of a 45 minute spin class on a stages indoor cycling bike, which has a left sided power meter. My right leg is definitely a bit stronger but does this make sense? Just feels like too large of a variance...

    Thanks.

    Is the watts stated for the spin class average power or normalised power?
  • imafatman
    imafatman Posts: 351
    My indoor power is like 20w lower than my outdoor power. Just get too hot. Can't really crank out the same efforts.

    Also what someone said about 20 minute power not carrying through to longer efforts is also true. My 20 minute power has increased quite a bit over the past year but it's very difficult to set out to achieve the 95% figure over the hour. Not unless you want to squeeze out a monumental leg breaking effort.
  • N0bodyOfTheGoat
    N0bodyOfTheGoat Posts: 6,057
    My best 20mins effort (292W) this year gives an FTP of ~277W with the 95% rule.

    My best real world "hour of power" (as I call it) is 249W, which included a ~2min stop at the top of the incline.

    Even accounting for that short stop, the 95% theoretical from a 20min effort is nowhere near a full 60min effort for me.
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  • CanyonBiker
    CanyonBiker Posts: 14
    Thanks for all the responses! To answer a question above, just average watts (not normalized). So, I assume my pacing and the like should still be based off of the 20 minute FTP test, right, even if it's not truly my hour power?

    To be totally candid, my 20 minute test involved some hills and some standing (where my watts increase significantly) so I wasn't sure if this was inflating my outdoors average but it makes sense that between having a stronger right leg coupled with heat could lead to a significant imbalance.

    I've also used the Xert garmin add-in and there I got closer to a 290 FTP (vs. 265 implied by the 20 minute test) but that didn't seem realistic.
  • Vino'sGhost
    Vino'sGhost Posts: 4,129
    imafatman wrote:
    My indoor power is like 20w lower than my outdoor power. Just get too hot. Can't really crank out the same efforts.

    Also what someone said about 20 minute power not carrying through to longer efforts is also true. My 20 minute power has increased quite a bit over the past year but it's very difficult to set out to achieve the 95% figure over the hour. Not unless you want to squeeze out a monumental leg breaking effort.

    Your FTP should be exactly that, a ,monumental leg breaking effort. The most you can squeeze out in an hour. OOOOOOO the pain. it's delicious.

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