FTP will often be on the order of 95% of a solid go as hard as you can interval. That said, people vary a good deal and it may vary between ~ 90% on the low end to as much as 97% for a very few select truly slowtwitch folks.

YMMV,

Hugh

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Genetics load the gun, lifestyle pulls the trigger.

for the 30min FTP test i take the avergare of that power and use it for my zones. if you did 20min you should subtract 5%. the best way to do your FTP test is 1 hour all out. that would be your true ftp number

Isn't the issue here that there is a level that you could physically maintain for one hour -your true FTP- but b/c that is very very tough, the 20 minute test all out -while not testing your true exhaustion at one hour- gives one-b/c it is more mentally palatable to "'last" for twenty minutes -an extrapolation - I.E. a measure of your physical potential -if you could be mentally tougher.

A 1hr test of FTP is hard because riding at FTP is hard...so I think the only way to know your FTP is to do a 1 hr test. Riding at FTP is just as much mental as physical, a 20-30 min test doesnt cut it.

I have found for myself and many riders I have tested on my CT that the 30 min CT indoor power and the 60 min outdoor power are very close to each other. Two things that I feel make is fair to extrapolate 30 min indoor CT to 60 min outdoor are the following:

1. Just can't get enough thermal regulation indoors, no matter how much air flow and I have good fans etc
2. Indoors, the concentration wanes, which is not so much the case outdoors

I found that 30 min is a nice balance point between not too much skew from anaerobic (on 20 min the last 90 second can be largely anaerobic, skewing the numbers more than over 30 min) and also the heat build up does not get insane, and mental concentration drops a bit over 20 min, but less than 60 min or 2x20 min (2x20 min still has more cooling issues and mental concentration issues). My 2 cents. I like 30 indoors.

Let me clarify the point - just because you can't tough out the hour test does not mean that the 20 or 30 minute tests are not valid as to your physical threshold -even though the mental aspect is another issue.

Dev,

You obviously haven't invested enough in super high velocity fans;) I'm probably one of the very few folks who takes along a precision anemometer when I go fan shopping. It's amazing how low a velocity most fans generate even ones that seem to be creating a tornado. Vornado fans are some of the worst performers despite their advertising.


Hugh

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Genetics load the gun, lifestyle pulls the trigger.

Yeah but it's not just the fan part, there is also a mental component when just watching a number on a screen (or a CT pacer) versus chasing your minute man in a real world 40K TT. World of difference. As others have pointed out, 20-30 min has physiological validity even though you may not be mentally able to tough it out indoors when it is meaningless....your physiology ability couples with race day mental make up can often allow for much higher numbers in racing than what one might see for an hour indoors (or what we might see in 20-30 min indoors).

I agree....just giving you a hard time but I do see nearly everyone with an indoor trainer underfanned by a huge margin. A typical box fan only puts out a 12mph breeze when on its highest setting. Hassock fans are better but still seldom over 16mph right up against the grill.

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Genetics load the gun, lifestyle pulls the trigger.

Yeah, certainly the thermal overload hurts the mental will to push. At 40 kph outdoors, with say a 10 kph headwind, a rider is being cooled with 50 kph relative airflow. As you said, your best fan is just barely 50% more than this. One thing I have noted, even with low flow fans...when you have minus 10C air entering through a window, its pretty good since you're moving very cold air over your body at low speed.

The only way to figure out exactly what your theshold is... is to go get tested. For a 30 min power test... I would recommend taking 95% and use that as the number for training. As long as your 30 min test is done on the same roads throughout the season you should be able to reasonably track your fitness.

Yep, 95% of a 30-minute test is fairly close to FTP. You can also do two 20-minute tests with a 5-minute recovery spin in between, and the average power of the entire 45 minutes is close to FTP.