Depends on the test. If you take a traditional 20 minute test, you take 5% off. I have seen one on youtube that just took the 20 minute value as the ftp, but there were some major sprint efforts before the 20 minutes, so I guess it was taking that into account.

You take the number as-is if you do the test for roughly an hour, give or take a few minutes.

What is/was the duration of your test?

---

Brian Stover USAT LII
Accelerate3 Coaching
Insta

20 minute test

---

"see the world as it is not as you want it to be"

From a 20mn test, the general rule is indeed "remove 5%" to the value measured in order to get estimated FTP.

I have not done the Sufferfest 4DP test before but from what I can remember the 20 min effort in this protocol takes your average 20 min power and uses this with no correction as your FTP, I think the theory being that because you have already done significant efforts as part of the test then your 20 min power more closely resembles actual FTP from the fatigue etc induced.

Most other protocols as far as I can gather take 95% of your 20 min average power.

Yes, if you do something significant just before, apart WU, it is not any more a "20mn test" but a "20mn portion out of a longer test", and of course the relation between power estimated during this "20mn portion" and FTP can be very different : instead of approximately 5% higher, it can be 3% higher, or equal, or lower than FTP. Depending what you have done before this 20mn portion ...

FWIW, I know almost nobody I follow on Strava that trains formally that could do 95% of their 20min number for an hour. Totally anecdotal.

Now, I only follow folks up to probably Cat 2 or 3 road racers so the variability index and their power duration curve is going to be a sharper drop than a TT or triathlete.

I'd expect the longer the effort durations that are your specialty, the closer to 95% you'd get.

I think it works for training zone purposes to use about 92% for me. 92% is much closer if you tend to train anaerobic more (bike racer) and 95% if you train aerobic more (triathlete).

Yeah, I've never actually tried to ride for a full hour to see if it works. But what I have done is found my supposed FTP, then that was used to find what I "should" shoot to ride at for 56/112 miles then trained to hold that for the necessary time and it's worked out okay. So I could see training for the specific 1 hour fitness attempt might make it possible. But I know that just because the 20 minute test says my FTP is xyz, that I can't hold that truly for roughly an hour unless I'm trained for that effort.

But I think the OP was trying to take that further and state that some people are not even taking 5% off the 20 minute test any more. I remember now where I saw it....GCN had one of the presenters do the Sufferfest test that another poster mentioned. He did some intense efforts before the 20 minute test, so he was starting already significantly tired. So that was the reason to take the 20 minute test at full value.

I've started using Trainer Road's ramp test. Like you said, I never could truly hold the 20 minute test anyway, so I just use that value to set training intensity. I wouldn't trust it nearly as much as a good 20 minute test to go out and pace a time trial purely from that info, but I didn't ever do that anyway. From the training based off that ramp test, I really learn what I can hold for a race. I prefer the ramp so far since it feels more repeatable. I had many bad 20 minute tests where I maybe didn't feel that great or just did a bad job at pacing and the whole test was useless.

It probably takes consideration for the type of training efforts you intend to do, as you mentioned. I've always used a warmup, couple VO2 max efforts, brief recovery, then 20-min test for FTP testing. I've also typically used 95% of that value and then rounded up to the nearest five or ten. But then I've had days where I've held above my supposed FTP on rides for longer than an hour because I was feeling really good that day... I've also had days where I couldn't seem to hold FTP for 10-minutes because of the opposite...

If the purpose is to set training zones, the difference in taking 100% or 95% of a 20-minute test is likely small. Might it be of value to take the higher number just to train harder?

---

Blog | Strava

95% of a 20-min test still way overestimates my FTP, even with a 5-minute all out VO2 effort done just minutes before. It depends on the individual. Likewise, a 30-minute test still overestimates my FTP. I like to do a 40-minute test, which I can mentally break it down into four 10-minute TT intervals to make it a great workout.

As a Triathlete (not bike racer)...yes, in-season I can hold 95% of 20mTT for an hour (or longer). But, I work up to those specifically during the build up to race-season following a progression like:

2x20 -> 3x15 -> 3x20 -> 2x30 -> 1x45 -> 1x60 -> 2x45 -> 1x90

all at ~95% FTP.

It just takes some time to adapt to the fatigue. Typically, I do a (2-3)xYY @ FTP on Tuesday, and a 1xZZ @ 95% on Saturday (in the middle of my long ride). Usually, its the same total duration of "ON" time for Tuesday and Saturday (eg, 2xYY = ZZ).

  
Lack of base endurance and sweet spot training, may be, leading to a steep CP curve ?

I've done 40+ min Zwift races averaging 105-110% of FTP (as calculated based on a 20min test, with the correction). Similarly I did a 1:12 ride on the weekend (including alpe du zwift), averaging a few watts over my FTP for the first hour (not surpsingly Zwift detected a new FTP value a few watts higher...), before the descent...

So what you mean to say is you're not good at the 20 minute interval of that particular testing protocol?

My understanding is the "20mn test" was always the "longer test" that included v02max depletion interval beforehand, and the 5% subtraction is still used. Doing simply a 20 min test without the depletion interval and only subtracting 5% is a misinterpretation or mischaracterization of the test http://www.hunterallenpowerblog.com/.../01/what-is-ftp.html

What was your 20 min test protocol

That sounds HORRIFIC. Just do a ramp test and get it over and done with.

I've been using the ramp test for nearly a year (maybe 6 tests in that time), and have found it to be great. Seems to be consistent with results from my previous estimates using either the 20' or 2x8' TR tests. It's changing in the way I'd expect it to change depending on training load. And also seems to track pretty well with actual performance over efforts of ~1 hour outside.

Re the latter, I suspect the reason many people would struggle to achieve their estimated FTP over an hour is simply that there are very few opportunities where you have both the conditions and motivation to do this. It takes a huge amount of motivation for most people to do a 1 hour max effort, it also takes a course where you can apply steady power throughout e.g. a mountain climb or a flat non-technical TT. I did a couple of bike races last year which were basically perfect for FTP testing - flattish section to start followed by a big mountain climb and a summit finish. ~40 and ~65 minute climbs respectively. The 65 minute effort was pretty much bang in line with ramp test results from a few weeks early - ramp test gave me 320W, climb was 315. 40 minute climb was at 322W, should have been higher for that duration but the flat section before the mountain was more technical and there were a lot of riders trying to break away and give themselves an advantage before the climb started so I had to work quite a bit harder before the climb started.

Can't see myself ever bothering with anything but the ramp test again, in my case it's certainly more than accurate and consistent enough for measuring progress and setting training zones. And it's so much better than the 20 minute test both in terms of the level of mental toughness you need to summon before attempting it, and the time after to recover.

couple of things to keep in mind

1. the 20 min test should have a 5 min vo2 max effort in front of it
2. the 20 min test is valid for ~ 60% of people.
3. Are you in the 60% or the 40%?

---

Brian Stover USAT LII
Accelerate3 Coaching
Insta

1. I did the Zwift 45 min test which I think has at that in it
2. I wasn't aware of that
3. I don't know and wouldn't know what to substitute for it instead.

---

"see the world as it is not as you want it to be"