Workouts effective at considerably lower FTP indoors?

I have the same problem but I wonder if it even matters. I have a general idea of what power I can hold for a given time outdoors and indoors with outdoors being considerably higher. However, I still feel that the TR workouts still are a great benefit to my outdoor efforts even though the indoor numbers are lower. Somehow working out indoors at a lower measured power pushes my already higher outdoor power up further. All I really have to do is discount the stupidly high TSS scores from my outdoor rides.

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I’m so grateful for this discussion as I’ve been thinking about this a lot recently.

Last year after a long-distance move I was without any kind of trainer for several months so I did my FTP test outdoors using the 8-minute protocol (much easier than trying to mimic a ramp test outdoors). A few months later I had a smart trainer and did a ramp test, reaching the same number as outdoors.

Fast forward a year and despite some solid training, rest and nutrition over the winter, my indoor ramp tests barely nudged up 1-2%. As the weather improved I went outside and did the 8-minute protocol and lo and behold, saw an increase of about 10% over my previous indoor test a week earlier. I’ve since retested indoors and out and find extremely consistent results.

I’ve learned two things from this exercise: First, my motivation to complete a ramp test indoors is admittedly poor now that the novelty of the ramp test has worn off. I may try alternating between that and 20-minute or 8-minute protocols indoors. Second, outdoor air cools from all directions, not just the front, so I may experiment with different fan locations or adding a third fan behind me.

In the meantime I use my indoor FTP for my indoor workouts and my outdoor FTP for my outdoor workouts.


When you put one fan in front of you and one behind, it can happen, that you have no air movement in the middle. When they have nearly the same speed they compensate each other, because the air can’t move in bove directions simultaneously.

People say that and it can be true. But proper placement and you can get some great airflow from a rear fan.

I have 3 in use.

  1. High and dead center, pointed down to my face and upper chest.
  2. Mid height and off to the side, pointed as my mid chest.
  3. Rear at hip height and off to the side, pointed at my lower back.

Good angles can even make for a decent swirl too, depending on the rooms walls. So, a rear fan can work, but placement matters.

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Absolutely what I was thinking – experiment until it’s as close to outdoors as possible, including some swirling if possible.

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