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Power Data Estimates for the climbing stages

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04 Jul 2018 12:42

Sky released this:

http://downloads.bbc.co.uk/england/pdf/froome_stage19.pdf

With notes, including this one:

Notes:
Due to the use of Osymetric rings, Chris's power numbers over-report by approximately 6% - so comparisons with other riders need to consider this.
User avatar Alex Simmons/RST
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19 Jul 2018 15:47

So what's the time adjusted for the trackstanding towards the end?
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Re:

19 Jul 2018 18:34

SeriousSam wrote:So what's the time adjusted for the trackstanding towards the end?


41'15" is the time I read in a tweet posted on the Top 100 site.

http://www.climbing-records.com/2013/07/all-time-top-100-fastest-rides-on.html
Cookster15
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Re:

19 Jul 2018 18:42

SeriousSam wrote:So what's the time adjusted for the trackstanding towards the end?


41:15 total. Quintana finished 47 seconds back after being 1:00 down with 3km to go. I think if they rode hard that gap would’ve gone out to 1:10 or before the climb flattened out. I think Quintana probably would’ve lost 1:15 if everyone went full gas. So many 30 seconds lost? I think the times are comparable to 2011.
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Re: Re:

19 Jul 2018 18:46

Durden93 wrote:
SeriousSam wrote:So what's the time adjusted for the trackstanding towards the end?


41:15 total. Quintana finished 47 seconds back after being 1:00 down with 3km to go. I think if they rode hard that gap would’ve gone out to 1:10 or before the climb flattened out. I think Quintana probably would’ve lost 1:15 if everyone went full gas. So many 30 seconds lost? I think the times are comparable to 2011.


2011 times were about 42+minutes for the GC group (Evans, Schlecks etc). Fastest was about 41:30.
Cookster15
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20 Jul 2018 06:13

I did my usual TDF ADH post examining the average ascent rate for the 5 fastest:
https://wattmatters.blog/home/2018/7/20/alpe-dhuez-tdf-fastest-ascent-times-1982-2018

This year was 12th fastest out of the last 14 visits to the Alpe by the TDF.

Image
User avatar Alex Simmons/RST
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20 Jul 2018 06:26

41:15 is ~ 5.7 W/kg
User avatar Alex Simmons/RST
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Re: Power Data Estimates for the climbing stages

20 Jul 2018 10:36

Interesting data. By comparison what were some of the numbers like back in the Armstrong era pre-ABP? How about in Big Mig's heyday?

Is this a good indication that things are clean(er) now? Has cycling finally turned the corner?
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Re: Power Data Estimates for the climbing stages

20 Jul 2018 16:09

I got close to what Alex has just using the rough VAM formula.

About the time lost doing to slowing down, jockeying for position: I agree with the other poster who suggests 30" max. I went back and looked at the "as it happened" report. Beginning with 10 km to go, these are the times that various km were raced (sometimes determined from a longer or shorter specified distance):

3:50
4:04
3:24
2:58
4:54
3:14
2:24
3:06
3:10
3:10
1:58

There are two outlier values. The 1:58 for the final km is presumably because the riders were sprinting at that time. The 4:54 time, going from 5 to 4 km left, corresponded to the steepest part of the stage. All the other values are fairly consistent, and don’t suggest any significant slowing down. In particular, over the last four km, the slowest time for a km was a little over three minutes, and the time from 4 km to 1 km was 8:44. Of course, there could be 20-30 seconds hidden in there somewhere, but not a lot more.

Regarding comparisons to the past. Even assuming 30" from slowing down, and a time of 40:45, this is much slower than the heyday of the 90s and early oughts. But not that many times since 2006 have been faster. They include two by Quintana, who was well off his 2013 and 2015 times yesterday, two by Valverde, also a little slower than before, and two by Froome, who was close to his 2013 and 2015 times, about the same if it was effectively 40:45. The view of many that high level blood doping has been curtailed seems supported, and the W/kg estimate is certainly plausible given known values of parameters like V02max and efficiency. That said, I don't think times like these are evidence that no one is evading the passport by raising his HT a few points. These times would be have been very unusual prior to the 90s (there may have been a few similar times in the late 80s, can't remember now), though how much that is due to different tactics, and better equipment, training and roads, who knows.
Last edited by Merckx index on 21 Jul 2018 19:31, edited 1 time in total.
Merckx index
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Re: Power Data Estimates for the climbing stages

20 Jul 2018 20:25

Merckx index wrote:I got close to what Alex has just using the rough VAM formula.

I didn't even bother putting the time/speed into my version of the Martin et al model, I just used an old chart of mine showing W/kg vs climb time:

Image

From this blog post of mine from 2010:
https://wattmatters.blog/home/2010/07/ascent-rates-and-power-to-body-mass.html

Merckx index wrote:The 1:58 for the final km is presumably because the riders were sprinting at that time.

The final km is pretty flat, even a section of negative gradient.
https://veloviewer.com/segment/4286076/Alpe+d'Huez+-+Tour+de+France
User avatar Alex Simmons/RST
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Re: Power Data Estimates for the climbing stages

21 Jul 2018 21:12

Alex Simmons/RST wrote:The final km is pretty flat, even a section of negative gradient.
https://veloviewer.com/segment/4286076/Alpe+d'Huez+-+Tour+de+France


Yes, I wondered about that. Looking at the profile at CN, I now see that the gradient drops off quite a bit at the end, a little more than 5% over the final 3 km. Your link does indicate a flat stretch at the very end, but it’s not clear to me exactly how long it is, and the CN profile doesn’t show this at all. Also, from the “as it happened” record, the final km was done in 1:58. If it had been flat, the leaders would have been considerably faster than that—unless, of course, they were slowing down intentionally. If they were, and it was flat, as much as 40-45 seconds could have been lost.

Going with CN, here are some numbers:

1) From the “as it happened” record, 6:41 for the last 2.5 km.
2) From the CN profile, an average gradient of 5.35% over the final 2.8 km, which I assume is the same for the final 2.5 km.
3) From the profile and “as it happened”, plus the VAM formula, the leaders were averaging about 5.9 W/kg prior to the last 2.5 km.
4) Based on 5.9 W/kg and 5.35%, the riders should have been averaging about 1500 VAM over the last 2.5 km.
5) Based on a rise of about 135 meters over the last 2.5 km, and the VAM of 1500, the riders should have done this stretch in about 5:22

This is about 1:20 slower than what they actually did according to the record. They supposedly did wait for Nibali during this time, but it’s not clear how long. They may have slowed down again near the end, but I would have thought Quintana would have gained back more time if they were this slow.
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Re: Power Data Estimates for the climbing stages

21 Jul 2018 21:56

Merckx index wrote:The 4:54 time, going from 5 to 4 km left, corresponded to the steepest part of the stage.


Anyone who has climbed it will confirm that the steepest part is at the start.
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Re: Power Data Estimates for the climbing stages

22 Jul 2018 15:27

vedrafjord wrote:
Anyone who has climbed it will confirm that the steepest part is at the start.


You should inform CN that their profile is wrong. And whoever surveyed it apparently could save a lot of money just by riding up it.

Everyone really slow on the PdN, roughly 4.5 W/kg if the speeds shown in the video are correct.
Merckx index
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Re: Power Data Estimates for the climbing stages

22 Jul 2018 21:56

Merckx index wrote:
vedrafjord wrote:
Anyone who has climbed it will confirm that the steepest part is at the start.


You should inform CN that their profile is wrong. And whoever surveyed it apparently could save a lot of money just by riding up it.

Everyone really slow on the PdN, roughly 4.5 W/kg if the speeds shown in the video are correct.

Someone I coach rode up ADH the other day - as part of a Haute Route event.

I did a quick grab of their elevation data and while it may not be perfect data you can see the key attributes of the steeper initial two kilometres and the flatter section near the top.

Image
User avatar Alex Simmons/RST
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Re: Power Data Estimates for the climbing stages

25 Jul 2018 14:09

I get 5.9 W/kg for Kangert up the first climb. He shouldn't have much left for the rest of the race. Same with the chasers, who weren't far behind. MJ group was about 5.40, which isn't very restful, either.

Averaging 5.9 W/kg on the final climb would be about 50 minutes.

Now I see that Quintana did the final climb in about 50 minutes.
Merckx index
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Re: Power Data Estimates for the climbing stages

26 Jul 2018 08:52

Merckx index wrote:I get 5.9 W/kg for Kangert up the first climb. He shouldn't have much left for the rest of the race. Same with the chasers, who weren't far behind. MJ group was about 5.40, which isn't very restful, either.

Averaging 5.9 W/kg on the final climb would be about 50 minutes.

Now I see that Quintana did the final climb in about 50 minutes.


#TDF2018 Incredible performances. Power data based on measured numbers in Strava (Ten Dam, Gesink). PC = Perfect Cyclist: FTP = 6,4w/kg and Riegel's power curve

Image

Source: https://twitter.com/Xav3r1us/status/1022396251826991104
Image Quack!
User avatar Lequack
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26 Jul 2018 12:42

Quintana broke the record for the first 8 kilometers of the climb which was set before on Pla d’Adet without the extension.

And new record on Col de Val Louron-Azet

http://www.climbing-records.com/
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Re: Power Data Estimates for the climbing stages

27 Jul 2018 21:19

Lequack wrote:Power data based on measured numbers in Strava (Ten Dam, Gesink). PC = Perfect Cyclist: FTP = 6,4w/kg and Riegel's power curve

Image

Source: https://twitter.com/Xav3r1us/status/1022396251826991104


:confused:

I don't understand why there is a difference between the "Perfect Cyclist's" assumed FTP of 6.4 W/kg and their estimated (using Reigel's formula) power of 6.15 W/kg for 47:15.

If somebody's FTP is indeed 6.4 W/kg, then at at least when fresh (as apparently assumed here) they would be able to sustain very close to that for that duration.

IOW, I don't that the original author really understands the physiology here (although this really only impacts the first row/last column of the table).
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28 Jul 2018 03:32

If the assumption is that FTP is power over exactly 45 minutes, power over 47.25 minutes would fit the Riegel formula with an exponent of 1.25, which seems way too high. If one uses an exponent of 1.10—still higher than the original formula, but apparently in the range of what others have used—one gets almost exactly 47 minutes.
Merckx index
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Re:

28 Jul 2018 16:23

Merckx index wrote:If the assumption is that FTP is power over exactly 45 minutes, power over 47.25 minutes would fit the Riegel formula with an exponent of 1.25, which seems way too high. If one uses an exponent of 1.10—still higher than the original formula, but apparently in the range of what others have used—one gets almost exactly 47 minutes.


IOW, the numbers/assumptions are whack.

(Note for others: based on analyzing data from runners,zctt Riegel came up with an
exponent of -0.07, or 1.07 as expressed above.)
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