Power Data Estimates for the climbing stages

[V3R1T4S]

So you know precisely the rolling resistance of each section of road, and every breath of breeze that may have floated across the rider?

+/- 20W maybe.

Sorry Alex, but as you somewhat smugly note later, this is the Clinic - not ApJ or Physics Review - and so I didn't feel I need to list all of the a priori assumptions beforehand.

Needless to say, on extended 12+% gradients with little wind, you can be can get extremely close. The climb the other day was mostly sheltered by trees and had good pavement during the steep segment that I make an *estimate*, and I did not note any appreciable wind on first glance.

Finally, I don't pass judgment when making a 5 min calculation or even a more detailed one. These are just fun, back of the envelope exercises.

 

[martinvickers]

W/kg is determined from the amount of work done.

In terms of climbing, work done is (simplistically) how much weight was raised how far. Hence rider + bike.

When calculating W/kg, you are looking at the weight (kg) that did the work (W). Only the rider did the work - the bike did not expend any energy. Hence divide work done by the rider's weight.

Hope that makes sense.

So am I right in thinking that the effort of dragging the bike upwards against gravity is already figured in the basic calculation of W, and therefore doesn't need to be reentered for W/kg, as that would just be double accounting?

And secondly, and at the risk of sounding stupid, does inertia fit into this anywhere (for simplicity's sake the effort of getting acceleration going)?

thanks

 

[Dear Wiggo]

So am I right in thinking that the effort of dragging the bike upwards against gravity is already figured in the basic calculation of W, and therefore doesn't need to be reentered for W/kg, as that would just be double accounting?

No. It's pretty much as I explained it. If "double accounting" were an issue, you'd get that happening because the rider's weight is used in both calculations.

And secondly, and at the risk of sounding stupid, does inertia fit into this anywhere (for simplicity's sake the effort of getting acceleration going)?

thanks

Because we are looking at the time for the rider to complete the climb as part of the calculation, inertia would only play a part if the rider was rolling (ie not pedaling) after the line itself. [ie they have spent energy propelling the bike and the bike is still moving despite the fact that the climb has finished]. Any time they roll during the climb (including just before the summit) will affect their climb time and hence be (mostly) accounted for. Riders definitely provide more energy to the bike+rider system, as they often roll for some time (no pedaling) after the finish line, but rarely are they crossing the line using inertia alone.

They're rarely rolling at the start of a climb either, so that initial acceleration is paid for by the inertia pre-climb start.

The post-finsih inertial energy would not be a significant factor in the equation.

 

[pepcalais]

If the average wattage of a climb is obtained from a powermeter on the actual bike then the power figure has taken total mass and loads experienced on climb into account ie rider mass, bike mass, wind etc.
Then a W/Kg figure is a valid one
If the average wattage is derived from a model calculator then ALL variables must be accurately nominated such as bike mass and vind speed and direction
so as to be considered accurate.

 

[Dear Wiggo]

If the average wattage of a climb is obtained from a powermeter on the actual bike then the power figure has taken total mass and loads experienced on climb into account ie rider mass, bike mass, wind etc.
Then a W/Kg figure is a valid one
If the average wattage is derived from a model calculator then ALL variables must be accurately nominated such as bike mass and vind speed and direction
so as to be considered accurate.

Noone considers the model-based calculation as accurate. Noone. Ball park at best.

Incorrect offsets, square chain rings and lack of calibration pre-climb can affect power meters too.

 

[Alex Simmons/RST]

Noone considers the model-based calculation as accurate. Noone. Ball park at best.

However, one can get very accurate values (to within +/- 2 watts even with a simple online calculator) by only looking at very steep segments and/or periods where a rider is solo or with one other rider, like today.

So which is it?

 

[V3R1T4S]

So which is it?

You can’t conflate two different poster’s words to attempt a “Gotcha!”. That just doesn’t work rhetorically.

I know you’ve done some work with calculations like these, such as the Alpe d’Huez ascent times, the TT pace simulator, etc. I think that it’s foolish and perhaps irresponsible to insinuate the innocence or guilt or a rider based on any single performance, with which you probably but may not necessarily agree.

However, for extremely steep segments the estimates can be quite good. Of course if you are on severely broken pavement or there is an extreme sustained wind it will be off.

Take Mt. Washington for example, 7.4 mi at 12.0%. I’ve done it in perfect weather as well as awful, windy weather - one of the worst in recent years, to be exact. So two different extremes. For the perfect weather the estimate came out barely a watt off and for the windy day it came out 19 watts off (but within 2 watts before reaching timberline). For that length and steepness mass obviously makes a big difference, so you have to be judicious in weighing yourself right before setting off (as well as knowing how much you lose per hour due to sweat, respiration, etc.), but if you do, you can get accurate values. If there is a 50 mph wind obviously that is going to throw things off. Before any more minutiae is brought up, I calibrated the SRM two days before both times with a known weight and in the gear ratio I expected to use most of the time up.

I’ve had similar success with other steep climbs. Again, after being judicious with the total mass going into the equations and recognizing if it is calm or unusually windy that day.

Edit: Because I would rather be watching LBL with my free time than continue this debate, I will summarize that I stand by my original statement that for steep segments you can get good estimates. I will let others make his or her own judgement on the validity of this statement.

 

[Alex Simmons/RST]

You can’t conflate two different poster’s words to attempt a “Gotcha!”. That just doesn’t work rhetorically.

I know you’ve done some work with calculations like these, such as the Alpe d’Huez ascent times, the TT pace simulator, etc. I think that it’s foolish and perhaps irresponsible to insinuate the innocence or guilt or a rider based on any single performance, with which you probably but may not necessarily agree.

However, for extremely steep segments the estimates can be quite good. Of course if you are on severely broken pavement or there is an extreme sustained wind it will be off.

Take Mt. Washington for example, 7.4 mi at 12.0%. I’ve done it in perfect weather as well as awful, windy weather - one of the worst in recent years, to be exact. So two different extremes. For the perfect weather the estimate came out barely a watt off and for the windy day it came out 19 watts off (but within 2 watts before reaching timberline). For that length and steepness mass obviously makes a big difference, so you have to be judicious in weighing yourself right before setting off (as well as knowing how much you lose per hour due to sweat, respiration, etc.), but if you do, you can get accurate values. If there is a 50 mph wind obviously that is going to throw things off. Before any more minutiae is brought up, I calibrated the SRM two days before both times with a known weight and in the gear ratio I expected to use most of the time up.

I’ve had similar success with other steep climbs. Again, after being judicious with the total mass going into the equations and recognizing if it is calm or unusually windy that day.

Edit: Because I would rather be watching LBL with my free time than continue this debate, I will summarize that I stand by my original statement that for steep segments you can get good estimates. I will let others make his or her own judgement on the validity of this statement.

Fair enough. Fun to chew the fat though.

I also stand by my suggestion that estimates posted in this thread should provide a range of W/kg numbers, and not an absolute number.

If a poster considers their estimate to be nailed with a high degree of precision, then they should state reasons for that (as per your example) and show a narrower range accordingly.

 

[Le breton]

........
I suggest as a standard including a +/- 2.5 m/s wind assumption into the estimates unless you are able to provide data to better nail this.

When I head towards my favorite mountain pass, which I will do in the next half hour, I just turn around if I encounter such a strong wind.

Right now, the airport, 4 km away mentions an average wind of 12 km/h, ie 3,3 m/s, with a direction implying it could be sometimes unfavorable and sometinmes favorable and presumably blowing at roughly 3.3 m/s divided by 2 at a cyclist height, ie 1.65 m/s.

However, I am pretty confident it will be barely noticeable.

I shall be back to let you know, time permitting.

 

[V3R1T4S]

Fair enough. Fun to chew the fat though.

Most definitely!

Some of the other super steep climbs that fall into the category of fun ones to calculate that are probably reasonably accurate due to good shelter are the Kitzbuheler Horn (after it kicks up to a sustained >12% under the powerline into the forest), the Zoncolan, and the upper 2/3 of the Mortirolo. I checked Bassos power against what Sassi said on for the Zoncolan, Mortirolo and Plan de Corones TT. The Zoncolan and Mortirolo came out within 0.1 w/kg; for Plan de Corones Sassis gave a 0.2 w/kg range the estimate came out in, but it's harder to pinpoint how close or far off the true value was unlike the Zoncolan and Mortirolo where an explicit value was stated.

You are right that wind can affect things drastically even on steep climbs. A local climb has the middle third at 1.1 mi and 10.6%. I did it a month ago twice on the same ride - once right on the front of a T-Storm rolling through (15-20 mph tailwind on exposed parts) and again right after it cleared up. My first climb was 30 seconds faster than the second one even though I produced more power the second time up!

Anyways, for sure it can be tentative to claim any sort of precision on a climb that has wind. Climbs like Ventoux and the Angliru I wouldn't even attempt to start a calculation.

 

[Le breton]

today's final climb

The last climb of the day seems quite suitable for accurate power estimation.

For a description of the climb in French you have this website

http://www.guillaumeprebois.com/l-actualite/preview-giro-altopiano-del-montasio.html

 

[BigBoat]

One would have to have picked a short sample of that climb due to the variable grades it had, and know the exact grade of the sample section which is very hard.

That said Uran seems to do around 6.0 w/kg based on his past power data, 6-6.2 FTP range seems to be the necessary requirement for a top 3 grand tour right now, along with unreal recovery abilities.

 

[Ferminal]

Nothing really special from Uran. Definitely not on the Siutsou level!

 

[the sceptic]

6.0w/kg? who would have guessed

 

[V3R1T4S]

I get 5.96 w/kg over 24:28 (for the solo part from when he attacked coming out of the tunnel to the finish) using CyclingPowerLab as well as Google Maps and Strava to get as accurate distance and elevation coordinates as possible.

He did 389w for 35:50 in the Paris-Nice TT a few years ago: http://home.trainingpeaks.com/races/team-sky-races/paris-nice-2011/stage-6---rigoberto-uran.aspx

Note if you click to view the actual file you can deduce that his weight - at least entered into TrainingPeaks - is 63 kg.

 

[Merckx index]

Not a climbing stage, but interesting to try to compare TJVG’s time in the ToC ITT today with Floyd’s in 2006. Not much doubt that Floyd was juiced then. Is TJVG clean? If so, one wouldn’t expect him to be as fast as Floyd.

The first 14.5 mi. of the course were the same for 2006 and 2013, at which point they diverged. In 2006, there was 2.5 mi of additional riding up Santa Teresa Blvd, all of it I believe fairly flat. In today’s course, the riders made a right turn on Bailey Ave. off Santa Teresa Ave. at the 14.5 mi. mark, then rode 3.5 mi of mostly flat road, followed by the final 1.6 mi. of climbing.

Floyd’s time for the 17 mi course in 2006 was 35:58, which suggests he passed the common 14.5 mi portion of the course at around 30:40. I don’t know what TJ’s time up the climb was, but I understand the record is 10:03, so presumably it took him at least that long. His time for the entire ITT was 48:49, so at worst I assume he got to the base of the climb at about 38:45, probably a little faster. I think there was a time check there, anyone have information on that?

The base of the climb was 18 mi from the start, so if he hit that at 38:45, I estimate he would have passed the common 14.5 mark at about 31:10, a little slower than Floyd. We can tentatively conclude that his average power was about 5% less. Significant, but not nearly as great as the claimed differences in power (per kg in this case) for climbers in the 90s vs. today. Moreover, as noted earlier, that 38:45 is probably an overestimate, in which case his time at the 14.5 mi mark would be faster. And since there was the climb at the end, riders today were probably holding back just a little on the flat portion of the course, relative to the way the course would have been ridden in 2006.

So I tentatively conclude that TJVG put out nearly as much power as Floyd. These are rough estimates, of course, assuming the riders are similar in body weight and shape, and also neglecting wind conditions, which could have been significantly different these two years. But like time checks, these are data that could be obtained and factored in. It seems to me that cycling officials should be making every effort to do so.

 

[Big Doopie]

Scientific...

 

[Alex Simmons/RST]

I don't know about when Landis rode but accounts I heard said there was quite a bit of wind this year which means any estimate is prone to large error.

the times posted by the women were a lot slower than I expected, so wondering what actual conditions were like

 

[roundabout]

Van Garderen's time was 39:05 at the split.

 

[iZnoGouD]

Training is advancing, in the past the main priority was getting the best doping and training was left behind
There is a lot of edge to be gained in training, and cycling nature itself enables you to push the body harder than the other sports.
While a runner may only do 3, 4h max a cyclist may reach 8h...
In cycling you have to have passion for it cuz it's a lot of hours training, in running you can just have external motivation and still be an elite athlete.

It's my opinion that with all the advances in training performance levels will keep improving and improving...
What's the limit? Is there even a limit? If there's a limit it clerealy isn't 6.2w/kg for an hour

 

[the sceptic]

the sky is the limit

 

[meat puppet]

Training is advancing, in the past the main priority was getting the best doping and training was left behind
There is a lot of edge to be gained in training, and cycling nature itself enables you to push the body harder than the other sports.
While a runner may only do 3, 4h max a cyclist may reach 8h...
In cycling you have to have passion for it cuz it's a lot of hours training, in running you can just have external motivation and still be an elite athlete.

It's my opinion that with all the advances in training performance levels will keep improving and improving...
What's the limit? Is there even a limit? If there's a limit it clerealy isn't 6.2w/kg for an hour

gains to be made, yes, but only marginal. literally.

WRT the lower para: Neil young once sang that numbers add up to nothin', and was right. Without context there's simply no telling. After a 5hr GT stage on the 2nd or 3rd week in a GT 6,2 is more than enough.

Any info on the Giro climbs? How's the pace been? Hasn't seemed stratospheric to me in any way. Till now I'm actually considering that I buy what I see.

 

[Netserk]

http://www.cyclismas.com/2013/05/analysis-giro-ditalia-stage-10-climbing-performance/

 

[iZnoGouD]

That's cool, more please!

 

[Netserk]

http://www.cyclismas.com/2013/05/giro-climbs-performances-in-pictures/