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Old 10-20-07, 11:50 AM   #1
tfro
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Question about finding FTP from a ride file.

I've had my PT for about a month now, but I haven't had the time/motivation to do a 20 min test to find FTP. So I originally just kinda guessed, and was way off and then reguessed based on some early rides and it seemed better. I'm now looking at a ride file from this morning's group ride, which was just under 2hrs total. If I look at a one hour chunk of it, my NP was 17 watts higher (287) than my guessed FTP (270) and my average power was decently lower (234). I was decently tired, but it wasn't all I could give for 1 hour.

So, is my FTP guess good or too low or what? Or should I really make time for a 20min test?

Edit: The entire ride was 256NP, 196AP for 2:05. I slowed down for the last 40mins to ride with my GF.
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Old 10-20-07, 12:05 PM   #2
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I would say that it is probably safe to use that 1 hour time chunk as your FTP but if/when you do your 20min test, compare the results. I have a feeling that you could have a slight underestimation but it is hard to say.
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Old 10-20-07, 01:03 PM   #3
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I've had my PT for about a month now, but I haven't had the time/motivation to do a 20 min test to find FTP.
Note nothing about 20 minute tests.
http://lists.topica.com/lists/wattag...?mid=910289158
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Old 10-20-07, 01:23 PM   #4
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Yeah, I've seen that. So then what am I to think since I'm trying to used method 1?

Last edited by tfro; 10-20-07 at 01:29 PM.
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Old 10-20-07, 02:02 PM   #5
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Yeah, I've seen that. So then what am I to think since I'm trying to used method 1?
That since you're using the least accurate method, there will be the greatest uncertainty associated with whatever value you use, and the best way to reduce that uncertainty is to use a more accurate method for finding FTP. For now, use 287, but realize that value might be off by a fair bit and work on getting a better value (since so much hangs off an accurate FTP number).
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Old 10-20-07, 02:09 PM   #6
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Note nothing about 20 minute tests.
http://lists.topica.com/lists/wattag...?mid=910289158
#5 mentions CP testing e.g. cp20min.
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Old 10-20-07, 02:13 PM   #7
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#5 mentions CP testing e.g. cp20min.
Or 18, or 22, or 16, 28, 17, 15, 25, 30, 37, .... There's nothing in the CP testing protocol that calls for any specific duration. The only requirements is that there be at least two tests and one be short enough and the other long enough.
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Old 10-20-07, 03:50 PM   #8
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Note nothing about 20 minute tests.
http://lists.topica.com/lists/wattag...?mid=910289158
And #6 mentions "the power that you can routinely generate during long intervals done in training." A 20 minute interval counts as a "long interval." If after your test, you end up with a number you can't routinely do in training, then modify it accordingly.

Note that, as per the test in _Training and Racing ..._, it's a good idea to do a 5 minute all-out effort, then a 5 minute rest, then the 20 minute test. This minimizes the affect of your AWC on the 20 minute test.
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Old 10-20-07, 04:02 PM   #9
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And #6 mentions "the power that you can routinely generate during long intervals done in training." A 20 minute interval counts as a "long interval."
All elephants are mammals, I am a mammal, therefore I am an elephant.
See my previous post regarding duration. Aside from that, I don't think anyone would classify multiple intervals done over a period of time as "a test." In fact, the language quoted is pretty clear this is not a (maximal) "test" but routine (i.e., unexceptional) efforts in training.

As to minimizing AWC, why not just do a Monod test and calculate it directly rather than try to remove it as a factor?
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Old 10-20-07, 04:15 PM   #10
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Aside from that, I don't think anyone would classify multiple intervals done over a period of time as a "test."
Quote:
Originally Posted by Andy Coggan
Ah, the great beauty of owning a powermeter: training is testing, and
testing is training. ;-)

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Monod tests are good too, if that floats your boat. And if you want to do 37 minute tests instead of 20, fine. There's no One True Test. There are lots of sources of information, all diagnostic but none prescriptive.

To the OP: if you had an hour at NP287 and didn't feel exhausted, I'd say try setting your FTP at 295 and see how that feels in training. Adjust accordingly.
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Old 10-20-07, 04:40 PM   #11
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Monod tests are good too, if that floats your boat. And if you want to do 37 minute tests instead of 20, fine.
It's not that you choose to do a 37 minute test, but rather you don't choose any specific time. The idea behind doing a Monod and freeing up the time is that the exact duration doesn't matter. Therefore, errors in pacing don't carry forward to errors in the results. To do an accurate fixed time test, the rider has to choose the effort that can be maintained for exactly the length of the test. To do a fixed effort test, pacing falls out of the equation. Pick a power that you think you can maintain for about 20 minutes and maintain this as long as possible. If it turns out the power chosen can only be maintained for 18 minutes or can be maintained for 24 minutes, it doesn't matter. Similarly for a power that can last about 5 minutes.
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Old 10-20-07, 05:01 PM   #12
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Thanks for the info, its clear I need to spend a bit more time figuring out my FTP.

At least I'm getting closer. My first guess when I bought the PT was 230.
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Old 10-20-07, 06:05 PM   #13
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Hey tfro, any graphs from that ATC ride, or at least some numbers for the parts before the route split?
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Old 10-21-07, 01:53 PM   #14
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The route split is around 15 miles, right? I think this is the last climb before the split. You can see where I go, then get stuck slow then go again.

Also, the 26mins we rode together after the warmup was 305NP, 231AP.
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File Type: jpg atc_climb.JPG (45.9 KB, 17 views)

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Old 10-21-07, 02:25 PM   #15
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It's not that you choose to do a 37 minute test, but rather you don't choose any specific time. The idea behind doing a Monod and freeing up the time is that the exact duration doesn't matter. Therefore, errors in pacing don't carry forward to errors in the results. To do an accurate fixed time test, the rider has to choose the effort that can be maintained for exactly the length of the test. To do a fixed effort test, pacing falls out of the equation. Pick a power that you think you can maintain for about 20 minutes and maintain this as long as possible. If it turns out the power chosen can only be maintained for 18 minutes or can be maintained for 24 minutes, it doesn't matter. Similarly for a power that can last about 5 minutes.
Good point. However, IMO the difference between failing at 19min and 21min can be explained away with associated errors and differences in mental toughness/motivation rather than a real difference in physiologically or biochemically defined "fitness." Or... if the tests purpose is to isolate and measure the aerobic system a small error in pacing is insignificant as the power/time-to-fatigue curve is pretty flat in that region.

Last edited by Enthalpic; 10-21-07 at 04:24 PM.
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Old 10-21-07, 04:23 PM   #16
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This is where I come in and plug MAP testing as a means for FTP determination, as it only takes about 11-12 minutes (at most) of effort and pacing is eliminated completely.

It's also important to remember that the two uses for FTP don't require exactness to the watt, but mostly require consistency of definition.

1. Training zones - these things are HUGE in the scheme of things. If you're off by 10 watts, it's not going to have a significant long term effect on your training. The longer you train, the more you will be able to "hone the zone" by feel as you notice a particular workout rates differently on the PE scale.

2. Calculation of IF and more importantly - TSS. If you're in to using the performance management system then ATL/CTL/TSB are all defined off TSS from day to day. An underestimated FTP will artificially inflate your TSS and your ATL/CTL lines over time. BUT, if you define FTP consistently, your ATL/CTL line will always be inflated by essentially the same amount, giving you consistent calculations of your TSB.

In the case of the OP, we're talking the difference basically between 275-295 FTP. If he does a workout with a normalized power of 250, the difference in TSS between those values is ~10 points. I went back and took 10 points off every workout for my last week and at the end of the week the CTL was a whopping 1 point difference. And at the end of the day, CTL is a highly individual thing. You can't/shouldn't compare it between people other than to get a rough estimate of how much one guy is training vs the next. It tells you nothing about composition of the training program.

It's really all pretty simple. If you can consistently do rides of an IF over 1.0 for an hour, your FTP is too low. I would also say that if you're doing rides day to day that include warm up/cool down/main session of .9+, you're probably estimating too low. So, rather than estimate. Test. Very few people do the 1 hour TT test, so go out do the Hunter Allen protocol (takes about 45 minutes total), Monod's points (do at least two, like Asgelle has said), or do MAP testing (about 30 minutes in total).
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Old 10-21-07, 08:00 PM   #17
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The route split is around 15 miles, right? I think this is the last climb before the split. You can see where I go, then get stuck slow then go again.

Also, the 26mins we rode together after the warmup was 305NP, 231AP.
Awesome, thanks! So that left part with zero power at 46mph was the coast-in off the bridge, then a couple spikes to 960W? The part where you got stuck was 0 power near the end there, or was that the coast down for the light?

I guess you haven't seen it in a long time, nor do you know the course that well, but thanks for digging it up. I remember I had an attack before the turn off Southwest Pkwy, then I completely buried myself for 2nd on that sprint into Bee Caves. I'll bet our wattage was pretty similar though.

You'll have to try that ride in July or August sometime when it's really hopping. This was the easiest I've seen it in two years (I don't normally get to do so much attacking )

Thanks again.
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