How robust is the W' W Prime feature in the activities

[JEFFREY_OHARA]

I’m like a kid with a new toy. So play I will. Trying to get a handle on what W’ means to me in the real world and on the activities breakdown.

I have come across two behaviors I don’t understand.

When I change the W’ on the activity it also changes the drop. Not much but it does.
Wouldn’t the drop stay the same?

It makes sense that the drop will change if you change FTP, but not W’

Which leads to my second observation;
The drop seems to change greater than maybe it should with a change in FTP.
But maybe I just need that explained to me.
Could someone explain it to me?

[bikeage]

Can you explain what you mean by “the drop”?

[JEFFREY_OHARA]

[R2Tom]

That doesn’t really answer the question.
The drop is the same (absolute difference) after changing W’. Or do you see a change in difference? I’ve tried it and the curve is the same, only the numbers shifted up or down depending on the change.

Only the values should change, so instead from 18 → 2 kJ, it shows the drop from e.g. 20 → 4 kJ.

The calculation for the drop is simple. Power x Time = J
Everything over FTP will deplete your kJ storage according to this formula.

Edit: ok. looked at the W‘drop from the summary field, indeed it changes. And it seems that the absolute values changes slightly too.
Maybe the recovery rate is calculated in parallel and changes the drop slightly.

[ilbonvi]

The question is legit: you can visualize the drop as a field. If you change W’, it also slightly changes the kJ drop.

This is the same activity, with only W’ modified (from 38k to 30k) — the drop changes by about 0.2 kJ.

[GarageLab]

If you want to investigate CP and W’ a bit more, I prepared spreadsheets for that. They allow you to see changes immediately and easily for analysis.

Modelling Human Performance

Just adding another Excel workbook to my Dropbox folder. I have Coggan, Skiba, and Xert metrics coded. This workbook has three sheets: Workout analyzer to estimate strain from a planned workout. [image] Performance analyzer to inspect a single performance and estimate CP and W’ from the performance. [image] PMC and Banister model implementations. These are basic, but they work. You can seed both models and fit the Banister model to performance tests to get individualized parameter…

[JEFFREY_OHARA]

@ilbonvi

The question is legit

Thanks. It isn’t much with a change in W’ But I think the the drop should be the drop.

And with changing FTP, it should change. It just seems like a lot.

@GarageLab Thanks I will check it out.

[MedTechCD]

@JEFFREY_OHARA

And with changing FTP, it should change. It just seems like a lot.

The amount of change will highly depend on the nature of the ride. If it was a ride around that FTP, change will be significant because there’s lots of time around the threshold where W’ is starting to count or not. If it was a ride with short hard efforts, the change will be less distinct.

[JEFFREY_OHARA]

@MedTechCD

The amount of change will highly depend on the nature of the ride. If it was a ride around that FTP, change will be significant because there’s lots of time around the threshold where W’ is starting to count or not. If it was a ride with short hard efforts, the change will be less distinct.

Yes I agree. I am looking at Efforts around above FTP.
And I get that I am increasing the area under the curve when I lower the FTP on an Activity. It just seems like a huge change almost double and would make me a rock star! lol I may be strong considering my time off the bike and less than 2 years back on, but not 34kj strong with the low estimate FTP of 284 Watts. And don’t jive with Highnorth, but does with the W’ Widget for the Garmin in the field with the High Estimate of 299 Watts and Intervals drop of 21.7kj (HN estimate is like 13kj)