FTP Test: Inside and Out

For those in the know, I have a question:

Considering I’ll be doing most of my training inside for the next few months, should I do my first (for first couple) Functional Threshold Test on the trainer? It appears that road tests and trainer tests sometimes (always?) yield different results.

For those not in the know, I will be back with less confusing content soon.

10 thoughts on “FTP Test: Inside and Out

  1. When doing FTP test the parameters must always be the same every time you do it. That is why pro’s mainly do it on the indoor trainer as every time it is done it is a consistent test. If you do it out on the road, the conditions will skew the results (IMO).

    • Bryan, Rob, very good point. I guess my concern was the fact that it appears (although it doesn’t seem to be universal) that you can get pretty big differences in results between trainer and road.

      So, if I did the test on the trainer and the FTP was 20 watts lower than it would have been on the road, but then proceeded to train outdoors, would I not be training too ‘light’? I’m probably reading too much into it, and now that you mention the ‘consistency’ point, I’m sure that outweighs any concerns I had.

  2. I agree with Brian. Even though a watt is a watt, regardless of indoors and outdoors, simple variables like temperature will change your power output. Whether you’re doing a FTP test or an AT test you want to simulate as close as possible the same conditions to monitor improvement over time.

  3. The difference between indoor and outdoors is control of variables (Brian’s point), but also psychological (for me, at least, I have a really hard time doing a 20min test in general, let alone on the trainer). Yet, the watts difference is typically not that large so it doesn’t matter that much, as long as you can live with a 5% error zone…

    Recall that the FTP is there as a benchmark, and that’s all it is: use it as a relative benchmark for your indoor training in winter to measure intensitit/TSS and progress, retest periodically and then the absolute number really doesn’t matter much. Once you get back outside, then you can do it there.

    I must admit that I haven’t done a 20min test in a long time, just because I don’t like 🙂 I typically aspired too high a number, and then I get discouraged when I can’t hold it during the test… I know, not good, but it is what it is. I’ve set mine now at 250 and am fine with that. It probably is within 10% accurate 🙂

    • I dread the thought of it, too, Jan, and I have been reading that I should be doing it throughout the season. Why didn’t anyone tell me it was going to be so hard..?

      Great point about the ‘relativity’ of the number. I did think about that and that is why I was concerned about getting it ‘right’, but as you say, if there’s only a 5% range of error, I doubt it’ll matter much.

      I’ve got mine set at 240 on the Garmin now, which is just a guess, but seeing as you are putting yours at 250, I think I’m pretty close. We’ll see soon enough – I’m thinking about doing an off-season test this weekend.

  4. Good to hear you got the Vectors as well, they’re good but you better torque them properly to get accurate readings.

    As for the FTP test: as long as you keep testing yourself the same way you’ll be alright and able to tell if you’re actually improving. 20 mins all-out isn’t that hard, just count down from 1200 to 0 and you’re there… Get the Sufferfest – Rubber Glove video, turn the fan on (highest setting) and get ready for some pain!

    • Have you got the Vectors, too, Patrick? I’m going to take the bike in soon and get it torqued correctly. So far the power seems to be consistent, though, which I take as a good sign. I don’t know if it’s ‘correct’, though, in absolute terms.

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