Intervals.icu eFTP

Last week after taking 7 days completely off of the bike I did a TR ramp test in the morning and got a result of 290w, which was the exact FTP I was training with before my week off. Intervals.icu gave me an eFTP it 289 for the ramp test workout.

That same afternoon I went and took a KOM on a local punchy climb, and Intervals.icu gave me an eFTP increase of +19w to 308 from 3min 50sec at 398w. This was the first time the eFTP has seemed overestimated, but was also the first sub 15min max effort I fed it since I started to use the software. I think if you have your minimum eFTP duration set correctly, the estimation can be very accurate.

1 Like

The one on the fitness page is a continuously updated number. Max efforts make it go up and it decays slowly if you reduce training. The ones on the /power page use only the selected data for the estimate e.g. only the last 42 days or the best data from last season etc…

You can also change the algorithm used on the /power page (MS 2P, Mortons 3P etc.) which is useful if you want to know what your W’ is and so on. Mortons 3P gives good results but you have to have good inputs. The default algorithm (matching to predefined curves) is more stable and only needs one max effort, thats why it is used for the ongoing estimate.

2 Likes

That might explain my eFTP. If I used that number, I’d :skull:

adding to the anecdotal data collection: For the past 4 months or so the intervals.icu eFTP has been consistently 2 watts lower than my respective ramp test results.
That’s pretty darn close, I would say.

3 Likes

What is your minimum time sample?

It’s the standard setting I believe… It’s at 180 s.

wow, I just switched back to 180s and got the same result. eFTP 2W lower than TR ramp test .

1 Like

on Xert, when I was on Base Phase, I set the Signature Decay Method to “no Decay” and it was under-estimate my FTP by 5watts. Now I set to “Optimal Decay” and I have the same difference of 5 Watt with an oscillation of +/- 3watt over 6 weeks, but I need to have at least a breakthrough every 2/3 weeks.

Awesome, changed the duration.

1 Like

Haven’t used intervals.icu, but have self tweaked or used other estimates (e.g. Lamarck on a “dumb” trainer/ Zwift Power).

Ramp Test doesn’t seem work for me - well it probably does for VO2 Max, but gives a lot lower than I can hold in the Lamarck. I can do up to supra threshold workouts, but may have to dial down the VO2 Max a bit.

Just my n=1, no idea am I screwing up my training doing this or not!

Keep in mind that Lamarck is 4x10mins with 3x2min recoveries. What you can complete there is likely higher than your FTP. Ditch the recoveries and you will likely feel quite different from a steady 40 minute effort.

Lamarck can be used as a gauge. But it must be interpreted, not taken directly.

1 Like

Or be pleasantly surprised that 1x46 at FTP is simply a hard effort that few attempt but is fully within capabilities.

1 Like

Yea, I’m in Build now, which apparently doesn’t work for their algorithm either. With little outdoor riding, I’ve been really consistent with indoor TR workouts, and that means no breakthrough rides for the estimated FTP, which means since the last ramp test, my FTP has been dropping consistently. I’ve never tried changing that setting, I didn’t know about it. It just seemed to all over the place for my liking. Maybe with no decay I’d fare better.

1 Like

Here how to change the decay method: Xert’s Magic Setting – Signature Decay – Xert
and here a brief description of the different options: Signature Decay Method – Xert

1 Like

The workout text is that the average can be used iirc (last time I was distracted by zwift!)

If I get a chance, I will check the workout text. The main workout info is lacking that statement.

1 Like

I don’t necessarily just use that workout, kinda know how sweet spot should feel at this stage - Carson is my go to if I’m still not sure. Anyway, still very much n=1, and very much a personal mental issue with the ramp test!

Yes. Here is the relevant workout text:

and

2 Likes

A quick return and update.

I’ve now done various VO2, sweet spot and endurance sessions with the FTP from the test that tracked close to the eFTP, all have either been easy (fasted endurance) or unpleasant but eminently manageable (VO2 or sweet spot).

So in my experience of n+1 if it shows you eFTP much higher than tested, it’s time to bite the bullet and get tested.

1 Like