FTP Test Protocol vs 40K TT Results
I conducted an interesting experiment that I thought I would share with respect to how our 5/20 FTP Test protocol compares to a 40k TT on the road.
1. 5/20 PT protocol - on 26 March, my FTP was 295, FTP/KG was 3.59, and my LTHR AVHR was 170. My VO2Max was 358, which was 1.21 of my FTP on this test.
2. 40k TT - today on 3 May, my FTP was 293, FTP/KG was 3.61, and my LTHR AVHR was 168. The additional metrics are that VI was 1.005 and AVSPD was 25.5mph
Analysis – the 5/20 FTP protocol is an excellent indicator of a 40k TT when you test correctly. In other words, you don’t sandbag the 5’ VO2 in hopes of raising the 20’ FTP. Just thought this was an interesting validation of what we already were told when we first drank the Kool-Aid back when! 
Comments
Hey - in your area, if you are ever in the Charlotte area this is a great TT series that I used to do:
http://carolinatt.org/v4/results/
This past week was my Short Course Week #10 Test week. Since I was a HR athlete for this same week in 2011-2013, I thought I would use the HR protocol with my power meter and see how they compare with the 5/20 protocol and 40K TT as well as my tests from the past several years:
1. HR Test - on 27 May, my AVSPD was 20.5 mph, LTHR - 165, and NP - 293 (trainer)
2. 40k TT - on 3 May, my AVSPD was 25.5 mph, LTHR -168, NP - 293 (road)
3. 5/20 PT protocol - on 26 March, LTHR - 170, NP- 295 (trainer)
So, this shows that not only is the 5/20 protocol an accurate assessment of the 40 K TT, but so is the HR test.
Anne here pretending to be Joe. I'm testing out the picture posting stuff.
I like your humor!
For those that are interested in tracking the correlation of the 5'/20' FTP test with respect to a true 40K TT FTP
, here are some recent numbers:
1. 5/20 FTP - took my week #14 test on 2/18. My VO2 (5') = 356W; FTP (20') = 287W (302 x .95); AVHR for FTP = 164; W/KG = 3.42
2. 40K TT - did today in 42 degrees with 8mph. FTP = 277W; AVHR for FTP = 149; W/KG = 3.33; my 20' FTP from my Garmin said 293
So, I think the difference was just the time it took me to get my body fully warmed up as evidenced by the lower HR in the colder 40K TT today.
Bottom line: the 5/20 protocol is an accurate assessment of the 40 K TT.
I'd say the 5/20 test over-estimates your FTP by 3-5% based on these results. Of course we only have a single data point to go on. your 5/20 was over 4 weeks ago and 10W higher FTP estimate - I'd expect a bit of progress assuming you've been on a structured training plan. The HR data is consistent with pushing harder on the 5/20 - remember you are flat out for only 20min there compared to 60min (?) for the 40k TT so your HR should be lower for the 40k. What was your 40k TT time anyway? What was your VI for the 40k? Did you pace it optimally?
3-5% doesn't sound like much and it may very well be within the noise of variability but just as with running tempo/threshold paces, going 5% too fast consistently can do more harm than good. Always opt for slightly conservative over slightly aggressive.
I think the worst test is the 5/20 because there is just too much variable to the first 5min interval... You seem to have this down .... I understand what that 5 minutes is supposed to accomplish but you have some that will dog it, some that will blow up on it (heck if I truly do an all out 5 min interval I am cooked for an hour and yes I have done it)... There is just no consistency that can be applied to that first interval IMO... And just using 120% doesnt work for all individuals ...
I recently accumulated 4 interesting FTP data estimates in the range of 33min to 46min.... Keep in mind I view those as just that 33min power to 46min power NOT 60 min power... But for my estimates I only take off 1% from those numbers because I only need to drop a little bit to be able to go the full hour based on past experience... Here are my data.... Very consistent and repeatable...
2/12 4 x 10'(2') 46' NP 214 just a hard 4 x 10 w/minimal rest and built a 46' NP interval to check
2/27 1 x 42' 42' NP 216 Originally set out to do 1hr.... Failed
3/4 1 x 33' 33' NP 214 Actual road race 12 miles
3/11 2 x 20'(2') 42' NP 215 old school 2 x 20 test
Lastly my thoughts on FTP... Not only do 99% of us not truly know what our FTP is but most of us are grossly over estimating it... Again kudo's to you for being in the 1%.... Over estimating an FTP does nothing except offer a little bragging rights...I see ton's of people who can't or don't hit estimates on wko's based off the FTP.... Bottomline is race day doesn't care about FTP it only cares about getting from point A to point B as fast as possible , and the athlete simply needs to know what power they can sustain for that duration of that even on that day... I'd even argue those that over estimate their FTP are actually doing a little harm if they are tracking metrics since they are actually under stating the TSS that they are wracking up during training... BTW I think this exists in the VDOT estimates for running as well!
Sorry I kinda rambled but this has been a great thread and I think of it often :-)
@ Joel - my VI for the 40 K TT was 1.0146 (273 Np/273 AP). It had 449' elevation gain and was an out and back. So, the course was essentially flat and the VI reflects that as well. I've done this course several times over the last 5 years so I know it well. My AVSPD was 23.4mph and my time was 1:03:41. I agree with your assessments, 3-5% is spot on.
@Tim - yes, the 5/20 has the risk of the 5' either too hard or too easy. I've done both and the 20' reflected it. So, I think the old school 2 X20' is lots more accurate. I like the correlation of your tests and they certainly give a good zone to work with for training to ensure you are hitting the right zones to get the proper training effect.
Thanks for your analysis!
N=1, my FTP achieved at 67+ minutes of cycling with a high VI 1.10+ seems a bit high. This comes after several weeks of tinkering/riding around with the FTP which I earned during the various TT/TTT.
I am in week 18 of my RP phase for my A race. So I lack the opportunity to really slay myself on some good FTP a workouts to test the results. But I will have many more 48/49/25KM TT/TTT opportunities. I will be able to test those results against some specific work and report back.