# FTP as a % of 8 minute test?



## MerlinAma

Carmichael sets up training zones based on 8 minute tests.

Is there a general correlation (%) between this number and your FTP which would be based on an hour test?

I'm sure there is, just don't know the number to use. I also understand the percentage would be an approximation.


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## hrumpole

knock 10 percent off, iirc.


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## Alex_Simmons/RST

It would be a 5% range typically (IOW it's not a fixed % of an 8-min test). The relationship between shorter and longer range power is variable.

If you want to test for FTP, then test for FTP.

if you can't do an hour long TT, then a 5-min max test and another of about 20-25 min within a week of each other would be perfect for assessing critical power, which will be very close to FTP.


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## hrumpole

Alex_Simmons/RST said:


> It would be a 5% range typically (IOW it's not a fixed % of an 8-min test). The relationship between shorter and longer range power is variable.
> 
> If you want to test for FTP, then test for FTP.
> 
> if you can't do an hour long TT, then a 5-min max test and another of about 20-25 min within a week of each other would be perfect for assessing critical power, which will be very close to FTP.


I dunno. I used the time crunched plan this summer, and the 10% rule of thumb in the Carmichael book seemed fairly close based on a comparison of RPE over the winter to when I was doing intervals based on a 20 min test. Like you said, 'tho, there's so much variability in individuals that the 20 min test might work better if the OP is truly FTP-curious. (It ain't like you have to study for it...)


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## Nevermiss

I've got about 10 rides with power data in Golden Cheetah and my Critical Power is calculated at 290. I followed Hunter Allen's book and did the 20 minute ride and subtracted 5% from that to calculate my FTP and got 285. I just signed up with CTS, so I look forward to hearing what my coach says, but I think I'm in the ballpark for what I need to know, at least for my FTP.

UPDATE: The CTS test involves a warm up, followed by an 8 min. all our effort, then 5 min easy,then another 8 min all out effort. There should be no more than a 10% difference between the two 8 min. efforts and these are then averaged and 10% subtracted for FTP calc.

My FTP based on 20 min. -5% was 285. My FTP based on the CTS test is 315. I have yet to do a one hour TT for a true FTP. My time between the two tests was a couple months and I do think my fitness improved from one to the other. However, I feel the CTS estimate is pretty good for setting my power levels for workouts. They hurt and I can barely hold them as prescribed for each workout. I'm pushing hard and feeling the pain as is designed for improvement with the appropriate work outs. The real value of FTP lies in the benefit of setting up a best "bang for the buck" training program. Otherwise, it's just a number measuring performance that you can talk about with your buddies like how much you can bench press :wink5: Then again....I'm a newbie so take it for what it's worth.


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## Zipp0

My FTP is 241W and the CTS 8 minute test I did said 269W. I did both tests about a month ago with several days in between and had no idea that the correlation was 10%. But for me, it did in fact work out almost exactily to 10%. (CTS = FTP+10%)


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## MerlinAma

Zipp0 said:


> ......... But for me, it did in fact work out almost exactily to 10%. (CTS = FTP+10%)


That's about what I would have guessed as a good rule of thumb. 

Thanks!


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## murdocki

There are plus and minus to all but this is a better test for Criterium/Cross racing as it is PVO2 work shorter. The number is about the same for both kinds of tests.


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## jajichan

That's ridiculous. 

8 mins is right around VO2 max duration. What percentage of your ftp that would equal is HIGHLY individualized. 

If you can't get out for a proper effort, just keep upping the workout intensity until you find one in the right range. 

Really doesn't even matter at this point, especially if you're new as the improvements will come quickly and getting outside will likely be an even bigger improvement just on its own.


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