# IF doesn't match power zones?



## kreuzberg (Feb 1, 2009)

Hi,
I think I'm missing something big here, but intensity factor is Normalized Power / FTP, right?
So I do some endurance rides in my endurance zone as defined by Coggan, but then I get an intensity factor that is very well below the defined IF zones for endurance (.75- .85), for example i'll do a endurance ride and get an IF of .65.
Whats up with this? Do I have to up my norm power for endurance rides to get within the defined IF zones? Or does IF not matter?


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## Undecided (Apr 2, 2007)

kreuzberg said:


> Hi,
> I think I'm missing something big here, but intensity factor is Normalized Power / FTP, right?
> So I do some endurance rides in my endurance zone as defined by Coggan, but then I get an intensity factor that is very well below the defined IF zones for endurance (.75- .85), for example i'll do a endurance ride and get an IF of .65.
> Whats up with this? Do I have to up my norm power for endurance rides to get within the defined IF zones? Or does IF not matter?


Does not compute.

When you say you "get" an intensity factor below the IF range of a particular zone, what do you mean? In Training Peaks? On a spreadsheet?


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## EricN (Apr 9, 2009)

have u updated your ftp? A 1.0 intensity factor is supposed to be "all out at FTP" if I recall correctly... .65 is what I would put most endurance rides with my currently un-updated FTP since april. Heck, my cross races where I preride semi-fast, warmup, then race at maximum (1.0) I put at .85 splitting the difference.... Numbers numbers...


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## EricN (Apr 9, 2009)

I think this is wko?


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## kreuzberg (Feb 1, 2009)

Not in WKO, just when I compute by myself, which is really easy to do, just norm power / FTP.


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## STARNUT (Jun 19, 2005)

are you using average or normalized?

Starnut


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## iliveonnitro (Feb 19, 2006)

So your IF is lower than what you think it should be?

Taking IF=Normalized power/FTP. Logically, to raise IF:
1. increase NP
2. decrease FTP

Either you aren't riding hard enough (1) or your FTP is set too high (2). Typically, it's #1.


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## Undecided (Apr 2, 2007)

kreuzberg said:


> Not in WKO, just when I compute by myself, which is really easy to do, just norm power / FTP.


Still doesn't make sense to me. 

You've determined your FTP. I'm going to assume it's 300 watts.

You've determined that a particular ride should be done at an IF of .75-.85 of FTP (NP 225 to 255 watts).

Then you go out and do the ride. If your NP is in the range, your IF must be as well. If it's not, then the IF can't be either.


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## kreuzberg (Feb 1, 2009)

Undecided said:


> Still doesn't make sense to me.
> 
> You've determined your FTP. I'm going to assume it's 300 watts.
> 
> ...


Ok look. Say it's 300 watts. Coggan's endurance zone would put you at 170- 225 watts for an endurance ride (NOT 225-255). If you rode around at 200 watts, which is right in the middle of that zone, it would give you an IF of .67. Which is not within the .75-.85 for endurance rides.
Okay. Can someone explain why it works like this.


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## Guest (Nov 4, 2009)

kreuzberg said:


> Ok look. Say it's 300 watts. Coggan's endurance zone would put you at 170- 225 watts for an endurance ride (NOT 225-255). If you rode around at 200 watts, which is right in the middle of that zone, it would give you an IF of .67. Which is not within the .75-.85 for endurance rides.
> Okay. Can someone explain why it works like this.



Because its Normalized Power not average power that is used to calculate IF. Where did you pull your Normalized Power from or how did you calculate it?


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## kreuzberg (Feb 1, 2009)

kytyree said:


> Because its Normalized Power not average power that is used to calculate IF. Where did you pull your Normalized Power from or how did you calculate it?


Technically it's BikeScore which is off of golden cheetah (silly software). But they shouldn't be that far off. It's not average power I'm talking about.


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## Guest (Nov 5, 2009)

According to the disclaimer at the top of this document its not BikeScore and NP are two different things. How close they are I'm not sure as I didn't read through the math. But taking something created from Skiba then applied to Coggan's work is not going to give you a result you can then compare to one of Coggan's charts. 

http://www.physfarm.com/bikescore.pdf 

From a post on the wattage forum:



> It's worth noting that Golden Cheetah will calculate BikeScore and
> xPower, which are calculated slightly differently from NP and TSS, but
> give you comparable numbers.


I don't have one but I think several have made an excel spreadsheet that will calculate normalized power if you want to see it.

EDIT: to add the link to the document that I left out before


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## iliveonnitro (Feb 19, 2006)

kytyree said:


> According to the disclaimer at the top of this document its not BikeScore and NP are two different things. How close they are I'm not sure as I didn't read through the math. But taking something created from Skiba then applied to Coggan's work is not going to give you a result you can then compare to one of Coggan's charts.
> 
> From a post on the wattage forum:
> 
> ...


Good call.

OP - You can't do this with Golden Cheetah. Did you manage to switch to WKO+ successfully?


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## kreuzberg (Feb 1, 2009)

iliveonnitro said:


> Good call.
> 
> OP - You can't do this with Golden Cheetah. Did you manage to switch to WKO+ successfully?


No, and I'm thinking now I'm not going to be able to. It's just too expensive to buy windows software, then parallels, then WKO+. Especially after I accidentally bought what I thought was the right software (windows vista) only to find out that it was an upgrade and not what i need ($#^&$!)


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