Power Data Estimates for the climbing stages

[Red Rick]

ammattipyöräily ‏@ammattipyoraily 7 min.7 minuten geleden
#Giro, Stage 19. Risoul

Nibali 33:36
Chaves 34:29
Majka, Valverde 34:58
Kruijswijk 36:17


In 2014, they went (jens blog)

Station de Risoul
2014:12,6 km@6,9%---31:45---average speed 23.81 km/h(Vincenzo Nibali)-RECORD
---32:20---average speed 23.38 km/h(Rafal Majka)

Note, they give different lenghts for the climbs. In the Giro they give 12.85 instead of 12.6. They also finish 7m higher.

 

[SeriousSam]

The relative climbing of Nibali against the others obviously varied a lot over this Giro. I'm curious about the extent to which this is because Nibali's absolute level went from good to horrid to best whilst the others remained at roughly the same level

 

[Red Rick]

Re:

The relative climbing of Nibali against the others obviously varied a lot over this Giro. I'm curious about the extent to which this is because Nibali's absolute level went from good to horrid to best whilst the others remained at roughly the same level

I think Majka was the most consistent with his level. So he might a decent reference.
Kruijswijk was totally consistent until his crash.
Chaves was quite consistent, but faded the last 2 days.
Valverde had 2 bad days when they raced like a mofo on high altitude.


I'd say Nibali regressed back to the level he was going toward. I think he paid for the long solo on the Corvara stage somewhat during his TT, which was about equally as terrible as Andalo. I'd say Kruijswijk would've been with Nibali had he not crashed.

Anyway, power estimation for today was 5.64 for 57 minutes on the Lombarde. Do note that

- There was tail wind
- Drafting
+ Climb was started pretty slow
+ Wasn't a MTF

I have that from the ammattipo something twitter

 

[Red Rick]

Posting here in anticipation of mutant stuff tomorrow

 

[Ryo Hazuki]

Re:

That's not the full climb. Also, what was the wind like yesterday? Looked to be cross/head wind on the final part at least

I really wonder if guys like you have ever been on a bike. when you ride 9%, wind has virtually no effect.

 

[Red Rick]

Re: Re:

That's not the full climb. Also, what was the wind like yesterday? Looked to be cross/head wind on the final part at least

I really wonder if guys like you have ever been on a bike. when you ride 9%, wind has virtually no effect.

Small differences happen to matter a lot uphill

 

[Irondan]

Re: Re:

That's not the full climb. Also, what was the wind like yesterday? Looked to be cross/head wind on the final part at least

I really wonder if guys like you have ever been on a bike. when you ride 9%, wind has virtually no effect.

I don't believe that. Even the slightest head wind will slow me down on a 9% grade, why would wind not affect a top pro? They are human after all.

 

[Alex Simmons/RST]

Re: Re:

That's not the full climb. Also, what was the wind like yesterday? Looked to be cross/head wind on the final part at least

I really wonder if guys like you have ever been on a bike. when you ride 9%, wind has virtually no effect.

What?

 

[Alex Simmons/RST]

Wind matters a lot when determining cycling power from speed, no matter the gradient.

Conversely, wind has a sizeable impact on speed for a given power, no matter the gradient.

 

[Alex Simmons/RST]

Here's the difference in climbing speed up a 9% gradient for a given power for a 1m/s headwind compared with a 1m/s tailwind for a rider total mass including bike of 73kg.

 

[Alex Simmons/RST]

e.g. at 400W (6.15W/kg) the speed difference between head and tail winds that you cannot even feel on your skin when standing still is 0.87km/h (a 4.4% speed variance) and equates to 8.5 seconds per kilometre time difference.

 

[Le breton]

Re:

Here's the difference in climbing speed up a 9% gradient for a given power for a 1m/s headwind compared with a 1m/s tailwind for a rider total mass including bike of 73kg.

ANYWAY, no wind today up Mont Chéry (twisting road).
For a 67 kg cyclist + 8 kg equipement 3,9 km X 9,7%
analyticcycling gives 448 watts + 2.5% transmission losses = 459 watts => 6.85 watts/kg

459 watts <==> roughly 5.9 l/mn
5.9 /67 = 88 ml/mn.kg

Hence need about 90 ml/mn.kg or a bit more to win. Barely less for Porte/Froome

Since Pinot is @ 93% of Contador and claims 85 ml/mn.kg VO2 max
I get a reasonable agreement since 85/0.93 = 91.4 ml.

 

[Escarabajo]

Le Breton, so are you putting Contador with 91.4 VO2 max?

 

[Le breton]

Re:

Le Breton, so are you putting Contador with 91.4 VO2 max?

Of course with a little grain of salt.
Just saying that those numbers seem consistent.
A bit over 90 ml/mn.kg needed to be a top level pro.
Not 95 to 100 ml/mn.kg like in a fairly recent past.
Or occasionally more (Rominger 55.921 for example) a few years earlier.

 

[Merckx index]

Re: Re:

ANYWAY, no wind today up Mont Chéry (twisting road).
For a 67 kg cyclist + 8 kg equipement 3,9 km X 9,7%
analyticcycling gives 448 watts + 2.5% transmission losses = 459 watts => 6.85 watts/kg

I assume you mean for Contador's time.

459 watts <==> roughly 5.9 l/mn
5.9 /67 = 88 ml/mn.kg

You can’t convert watts to oxygen intake without knowing fractional utilization at threshold and efficiency. Moreover, since this was such a short ride, the fractional utilization during this ride should be a little higher than that determined in a conventional threshold test. So even if you knew utilization at threshold and efficiency, you could not use those values to determine V02 max from the ride, unless you had data showing power over various time intervals (as Pinot has published).

Hence need about 90 ml/mn.kg or a bit more to win. Barely less for Porte/Froome

Since Pinot is @ 93% of Contador and claims 85 ml/mn.kg VO2 max
I get a reasonable agreement since 85/0.93 = 91.4 ml.

Beyond the problem that this ride was shorter than a threshold exercise, you can’t assume that Pinot and Contador are the same in sustainable utilization and efficiency. E.g., two riders with the same utilization could have the same 6.85 watts/kg if one rider had a V02max of 90 and an efficiency of 24%, and another had a V02max of 85 and an efficiency of a little more than 25%. The rider with a V02max of 85 could have a higher power output than the rider with a V02max of 90 if his fractional utilization was greater.

 

[Alex Simmons/RST]

The VO2max values estimated from a TT effort depend on one's assumptions for the individual rider's gross efficiency and for the fractional utilisation of VO2max for the effort (and in this case, a rider's anaerobic work capacity). If we take 6.85W/kg at face value, then:

TT power/kg = Energy per litre O2 (J) x VO2max (ml/kg/min) x Fractional VO2max at threshold (%) x GME (%) / 60 (seconds/minute) / 1000 (ml/litre)

hence:

VO2max (ml/kg/min) = (W/kg x 60000) / (energy per litre O2 x Fractional VO2 utilisation x GME)

energy per litre of O2 varies a little depending on a few things but let's say 20900J/l

so if GME is 24% and fractional VO2max utilisation is 95% say, then
VO2max = (6.85 x 60000) / (20900 x 0.95 x 0.24) = 86.3ml/kg/min

Naturally estimates for GME and fractional VO2max utilisation can vary somewhat.
e.g. change GME by 1% (absolute) and VO2max estimate changes by ~4ml/kg/min.

It also get's a little tricky when considering these shorter supra threshold efforts as there is a not insignificant contribution from anaerobic work capacity, which for this effort would supply ~ 5% of total energy demand give or take a % or two. That is also individually variable. IOW about 5% of the power (~23W) was not powered via O2 utilisation. So the aerobic component of power production for estimation of VO2max should be reduced from the total power output accordingly.

So if anyone can tell us what his GME is, what his fractional utilisation of VO2max was for the effort, and what his anaerobic work capacity is, then we can, assuming the power estimate is correct, make an estimate of VO2max.

Otherwise it's just speculating on VO2max within a range of about 15ml/kg/min.

 

[Alex Simmons/RST]

Didn't see your post MI until after I'd posted mine. We're basically saying the same thing.

 

[Merckx index]

Re:

Didn't see your post MI until after I'd posted mine. We're basically saying the same thing.

I always get my numbers on power - V02max relationship from your blog, specifically the one called Looking Under the Hood, which has three graphs that give you the relationship at a glance. I highly recommend it for others here who want to discuss this.

http://alex-cycle.blogspot.com.au/2013/08/looking-under-hood.html

 

[Alex Simmons/RST]

Re: Re:

Didn't see your post MI until after I'd posted mine. We're basically saying the same thing.

I always get my numbers on power - V02max relationship from your blog, specifically the one called Looking Under the Hood, which has three graphs that give you the relationship at a glance. I highly recommend it for others here who want to discuss this.

http://alex-cycle.blogspot.com.au/2013/08/looking-under-hood.html

Ah, OK, yes. those charts are graphical representations of the formula I posted above.

For anyone interested, I created a chart of same thing after the Froome VO2max test data were released last year:

http://alex-cycle.blogspot.com.au/2015/12/looking-under-froomes-hood.html

in that chart it plots Froome at 90% fractional utilisation of VO2max.

 

[Le breton]

Of course, I was perfectly aware of the criticisms that would greet my post.
Thanks Alex for your links which of course I have seen before.
I didn't explicitly take Contador as the subject and pointed out that the top 3 produced basically the same performance.
The average time for those 3 (CPF) was 11:42 or 43. If you subtract 6-7 s for the time loss due to the 0 starting velocity,
I get the average W/kg of CPF by using 11:36 as the time needed for the climb.

I would be EXTREMELY surprised if somebody proved that there is more than 0.5% difference in GME between those 3 guys which basically have very comparable characteristics as cyclists. It's also quite likely that they ended up with similar lactate levels and used amounts of anaerobic resources that are quite comparable.
Therefore we could say that I calculated things for an average of C, P and F.
There have been discussions of GME on the forum in the past; GME was used as a masking agent to dissimulate L.A. doping (remember 120 rpm)
Then Ed Coyle, in his now infamous study, produced just one reliable piece of information : LA's efficiency was no better than that of other endurance cyclists, from memory he needed 5 l/mn of O2 to produce 400 watts, while with the standard 78 W/liter of Mr Joe Cyclist he would have produced 390 watts.

Anyway, that uphill time trial is a classification based on the W/kg that the 3, C, P and F, are able to produce on about 11:40.

I think it's fun to try and estimate their VO2, either actual or max.
Then, if you don't like my method, offer your's.

But, I think it would have been important to FIRST check the altitude difference, which I intend to do at the first occasion I get.
I was implicitly hoping for help on the matter.

 

[Merckx index]

Re:

I would be EXTREMELY surprised if somebody proved that there is more than 0.5% difference in GME between those 3 guys which basically have very comparable characteristics as cyclists. It's also quite likely that they ended up with similar lactate levels and used amounts of anaerobic resources that are quite comparable.

There have been several studies of elite cyclists, links to which have been posted in the Clinic before, which demonstrate fairly wide ranges in efficiency, certainly far more than 0.5% (I assume you mean 0.5% efficiency difference, as in 22.0 vs. 22.5, rather than 0.5% value difference, as in in 22.0 vs. 22.1). While not all physiologists seem to believe some of the really high values reported, in the upper 20s, even in the well-established lower range efficiencies may vary by more than 3-4%, easily. There's really no reason that I know of to assume that Contador, Porte and Froome should have similar efficiencies.

 

[Le breton]

One of the discussions you might be thinking about :
viewtopic.php?f=6&t=8170&start=20

I have to admit that the labs view of the efficiency situation looks pretty pathetic.

 

[Alex Simmons/RST]

GE does vary somewhat between professional cyclists, plenty of science on that. Most definitely more than 0.5% in absolute terms. And VO2max varies quite a bit too (which explains somewhat the variability in GE while performance is similar as there may be a loose inverse correlation between VO2max and GE). Anaerobic capacities also have a fairly wide range of individual variance, but there impact varies depending on the duration of effort. the longer it is, the less it matters.

There's nothing wrong with estimating VO2max, but we just need to recognise that doing so from W/kg estimate on a shortish climb by definition means one needs to make guesstimates of several other attributes with sizeable individual variability.

 

[Merckx index]

Re:

One of the discussions you might be thinking about :
viewtopic.php?f=6&t=8170&start=20

I have to admit that the labs view of the efficiency situation looks pretty pathetic.

No, I was not thinking about Coyle's study of LA, which has been discussed to death here.

The studies discussed here:

viewtopic.php?f=20&t=29830&p=1773705&hilit=efficiency#p1773705

Note that in one of the studies, the SD of efficiency was 2.6%.

These are just the studies in which very high efficiencies were reported. Most literature reports somewhat lower efficiencies, but these are usually not studies of elite riders. And in any case, even in these studies, the variation of efficiencies is fairly large, e.g., 18-23% might be a typical range.

 

[Le breton]

For the Vuelta 2011, Froome's power distribution curve posted on Cyclingnews and later removed showed a power of 510-515 watts for a duration of 11:40.
512/6.85 = 74.7 kg
I had printed that curve and later posted it on the forum.