Power Data Estimates for the climbing stages

[Cyivel]

Has anyone calculated nibali's numbers for today?

vetooo ‏@ammattipyoraily 7h

Giro del Trentino, St. 4, Sega di Ala (11.15km, 9.71%, 1083m). Vincenzo Nibali: 37 min 46 sec, 17.71 Kph, VAM 1721 m/h, 5.79 W/kg. #Trentino

 

[Parrulo]

So not particularly remarkable. To be honest it looked more impressive on TV.

 

[Bavarianrider]

vetooo ‏@ammattipyoraily 7h

Giro del Trentino, St. 4, Sega di Ala (11.15km, 9.71%, 1083m). Vincenzo Nibali: 37 min 46 sec, 17.71 Kph, VAM 1721 m/h, 5.79 W/kg. #Trentino

How/Where did you calculate that
Using those numbers i get 6,0 Watt/Kilo!

 

[Cyivel]

How/Where did you calculate that
Using those numbers i get 6,0 Watt/Kilo!

Not me, this person

https://twitter.com/ammattipyoraily

 

[iZnoGouD]

5.9w/kg here

 

[Bavarianrider]

Not me, this person

https://twitter.com/ammattipyoraily

2peak says 6 which i found more believable to be honest

 

[Cyivel]

2peak says 6 which i found more believable to be honest

I was expecting higher than 5.8 honestly but they seem generally reliable and often have the calculations quoted on here fwiw

 

[Big Doopie]

Nibali has been connected to Ferrari.

Nibali is a fraud. Just like schlecklet, clentadope, scarponi, valverde and Armstrong.

Here's hoping he fails and spends time in prison.

 

[V3R1T4S]

More accurate, perhaps

I did the same calculation earlier, but to be honest, due to Astana driving it for the first third during the shallow part of the climb the accuracy is probably not better than +/- 5%.

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.

I did this using Google Maps street view and Strava to calculate Nibali's w/kg from when he attacked right before the tunnel to when he crested and started down the short downhill. Here is what I got:

Elevation: 1151 ft / 350.8 m
Distance: 1.57 mi / 2.53 km
Duration: 10:40
Mass of rider: 61 kg
Mass of equipment: 8 kg
Power: 399.9 watts / 6.56 w/kg

Here is what I got from when Nibali attacked until the finish:

Elevation: 1565 ft / 477.0 m
Distance: 3.28 mi / 5.28 km
Duration: 17:08
Mass of rider: 61 kg
Mass of equipment: 8 kg
Power: 364.8 watts / 5.98 w/kg

Source: http://www.rst.mp-all.de/bergauf.htm

 

[Ferminal]

I was expecting higher than 5.8 honestly but they seem generally reliable and often have the calculations quoted on here fwiw

Yeh I got 5.8 - 5.9 Ferrari. It's still pretty high considering almost half of that was no drafting (it was rather inconsistent, were some flatter sections). Again, it's basically a 40 minute Alpe d'Huez (Siutsou the other day sub-40').

 

[Alex Simmons/RST]

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 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.

 

[xcleigh]

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.

When working out watts, bike and rider weight is used as part of the calculation it seems. To work out w/kg is watts then divided by the total mass of rider and bike or just rider mass? It appears to be just the rider in the above calculations. Any reason for that? Just seems odd. Sorry if this is a fundamentally stupid question

 

[Dear Wiggo]

When working out watts, bike and rider weight is used as part of the calculation it seems. To work out w/kg is watts then divided by the total mass of rider and bike or just rider mass? It appears to be just the rider in the above calculations. Any reason for that? Just seems odd. Sorry if this is a fundamentally stupid question

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.

 

[Le breton]

So you know precisely the rolling resistance of each section of road ....?

Come on! Why even mention rolling resistance uncertainties? Did he have to ride over cobbles or muddy dirt roads sections?

 

[Alex Simmons/RST]

Come on! Why even mention rolling resistance uncertainties? Did he have to ride over cobbles or muddy dirt roads sections?

Presumably not, but then that would just throw the estimates out by more if he did.

But seriously guys, put some error bars on your estimates, as you simply cannot makes such claims of precision when you do not know all of the details necessary to make such a claim.

Even the barest of breezes impacts the speed - power relationship when climbing more than the precision claimed here.

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.

 

[Alex Simmons/RST]

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.

Of course the work done is not solely that to lift a mass up a certain height, but also includes that required to overcome other resistance forces such as rolling resistance, air resistance and drive train friction.

Of course when climbing the energy demand to overcome gravity is dominant, but wind speed and direction can and does play a sizeable role in the speed-power relationship when climbing.

So any estimates should account for the wind vector.

e.g. 2.5m/s would give an error range of approx +/- 7% in W/kg estimates on an 8% gradient with a 5.7W/kg rider.

Or put another way, what one might estimate as 5.7W/kg when there is dead calm, could be anywhere in a range of 5.37W/kg - 6.25W/kg depending on wind.

 

[Ferminal]

Of course the work done is not solely that to lift a mass up a certain height, but also includes that required to overcome other resistance forces such as rolling resistance, air resistance and drive train friction.

Of course when climbing the energy demand to overcome gravity is dominant, but wind speed and direction can and does play a sizeable role in the speed-power relationship when climbing.

So any estimates should account for the wind vector.

e.g. 2.5m/s would give an error range of approx +/- 7% in W/kg estimates on an 8% gradient with a 5.7W/kg rider.

Or put another way, what one might estimate as 5.7W/kg when there is dead calm, could be anywhere in a range of 5.37W/kg - 6.25W/kg depending on wind.

Do you have to consider the path of the road when accounting for wind?

For example yesterday was an 11km road but only half of that was southerly displacement A to B.

Overall I agree about the errors and it makes the single climb sort of analysis rather pointless. If you have a 10% error either way that's basically Sandy Casar at the bottom and Marco Pantani at the top.

 

[Dear Wiggo]

Of course the work done is not solely that to lift a mass up a certain height.

Of course. Which is why I wrote (simplistically).

In terms of explaining why weight(bike+rider) is used to calculate the work done but only weight(rider) for calculating W/kg, - ie the question to which I was responding - my explanation avoids complications such as W/m^2 frontal area, rolling resistance, wind resistance, drive train losses, etc.

 

[xcleigh]

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.

Perfect. Thank you for that, it does makes sense now (I should have paid more attention in my maths and physics classes!)

 

[nogav1ca]

Don't you get with Ferrari's formula W/kg for total weight rather than just rider's?

 

[Netserk]

Don't you get with Ferrari's formula W/kg for total weight rather than just rider's?

No .

 

[The Hitch]

Nibali has been connected to Ferrari.

Nibali is a fraud. Just like schlecklet, clentadope, scarponi, valverde and Armstrong.

Here's hoping he fails and spends time in prison.

Evans also is connected to Ferrari

And you forgot to mention Millar. Oh wait forgot, it's not wrong if you like them.

 

[Alex Simmons/RST]

Do you have to consider the path of the road when accounting for wind?

Of course, which would be the bit where I said:

wind speed and direction can and does play a sizeable role in the speed-power relationship when climbing.

So any estimates should account for the wind vector.

Clearly when a rider changes direction, the relative wind vector changes.

For example yesterday was an 11km road but only half of that was southerly displacement A to B.

Overall I agree about the errors and it makes the single climb sort of analysis rather pointless. If you have a 10% error either way that's basically Sandy Casar at the bottom and Marco Pantani at the top.

Which is why such exercises are pointless as a Clinic debating topic.

As a bit of fun to discuss what it takes to climb at a certain rate or make it up your favourite col, sure, nothing wrong with that, but as a forensic tool to assess (non-)doping plausibility, well I'd put it in the same basket as "he's a pro therefore he's doping" category of forensic analysis.

Now if you start to assess the same climb, with many riders, over many years (decades), it's possible you can pull out trend data, but even then isolating one data point can be problematic if the error bars have not been included, or that you can be assured that the unknowables in the equations have in fact been nailed down.

As Rumsfeld said, there are known unknowns. So put error bars on them.

 

[Alex Simmons/RST]

Of course. Which is why I wrote (simplistically).

In terms of explaining why weight(bike+rider) is used to calculate the work done but only weight(rider) for calculating W/kg, - ie the question to which I was responding - my explanation avoids complications such as W/m^2 frontal area, rolling resistance, wind resistance, drive train losses, etc.

I think I'd put it this way:

One uses physics to estimate what's required in getting a bike + kit + rider to the top within a certain time, or uses a power meter to measure it.

However, as you said, it's only the actual rider doing the work.

Hence as an indicator of the rider's physiological capability, it is typical to normalise that power output to rider's body mass only.

 

[pepcalais]

So........
If a rider on a 7kg bike with no wind rides solo up a climb in 30mins makes ?w/kg
Then the same rider on the next day riding a 9kg bike into a slight headwind rides thr same climb in 33 mins his ??w/kg has gone down and our calculations have not taken these variables into account
W/Kg is only valid when all variables are known accounted for and kept constant and repeated.Changes in these have massive impact on final W/Kg figure.Even though we only take into account rider mass he is still obligated to shift the TOTAL mass up the climb.The total amount of mass is the predominant load.If he rides a 20kg bike we do not consider that yet it skews results to the point they dont count.
W/riders Kg is fine as long as all other variables are unchanged from one test to another.
Or have I got it wrong