http://www.cyclingnews.com/news/team-sky-reveal-froomes-tour-de-france-data-from-stage-10
5.78 watts/kg. at a VAM of 1602.Seems reasonable, if we accept the 6% overestimation of power due to the placebo rings.
If this is correct, certainly these numbers are not out of this world.
Well, they can’t fudge the VAM. That’s elevation and clock data. So, the question is can 5.8 watts/kg produce 1602 VAM?
What’s the consensus on a 6% overestimation with non-round rings?
I’ve heard from a few sources that an overestimation happens, but I’m curious on how valid people think 6% is.
It’s in Sky’s interest to give a conservative AP and NP for Froome’s rides.
That would depend on wind, drag, drive train efficiency, Crr etc. Right?
after races I like to go back and punch my numbers (weather, power, etc.), into bestbikesplit and compare it to my real world times. Based on recent results, the q-rings I use along with with a power2max suggest there is no boost in power for me (the 6% suggested above). The results are almost always very close to the bestbikesplit estimate. With that said, I might just be 6% more slippery than bestbike split knows about. who really knows?
That would depend on wind, drag, drive train efficiency, Crr etc. Right?
Right.
The fact that several riders reported a headwind on the climb means that those Watts will have to stretch a bit further than usual.
So you’re of the opinion that the inflation is much smaller (if there even is one)?
Do Q rings behave differently to Osymetric in terms of power meter readings? Osymetric are a much less consistent shape compared to the uniform ovals of Q rings.
http://www.cyclingnews.com/...e-data-from-stage-10
5.78 watts/kg. at a VAM of 1602.Seems reasonable, if we accept the 6% overestimation of power due to the placebo rings.
If this is correct, certainly these numbers are not out of this world.
Why do you need to subtract 6% to declare the numbers reasonable?
“It’s difficult to indicate the exact start of the climb, so I’ve analysed the last 15.3km, which is an effort of about 41 and a half minutes.
“For that 41:30, Chris had an average power of 414 watts, which gives a 1602 VAM. We know power Osymetric chainrings (used by Froome) over estimate power by about 6 per cent. That’s why it has to be considered when interpreting Chris’ power. With his weight hovering around 67.5kg that gives a correct power of 5.78 watts per kilo.”
My opinion based on only my data, is that q-rings don’t change power readings much at all. This is simply based on having my results match the bestbikesplit results.
This quote here is probably as interesting as anything else, when talking about the climb up La Pierre-Saint-Martin.
“The attack I looked at was a period where power was over 450 watts and it was about a 24 seconds duration. There’s an average power of 556 watts, with a peak power of 929 watts. Again that’s just the power metre and does not include the 6 per cent adjustment (for O-symmetric).”
The highest power that Chris averaged for 10 seconds was 652 watts, which is 60 per cent of his max power. His average speed was 25.3km/h and his maximum speed was 27.7km/h.
“To put that in context, when you look at the four-minute period when the GC contenders were largely still there, the power was 449 watts and the VAM was 1777. Four minutes after the attack, the power was 435 watts. So after that initial attack, Chris’s power was lower than in the four minutes leading into the attack, yet he continued to ride away from Quintana and the others.”
Read the article.
Motor post attack?
DB was interviewed on TV show Stade2 and he gave what I thought was a pretty believable talk. Do I find some performances suspect? Yes. Do I think there is generalized doping at Sky, and DB knows about it? I don’t think so. But I may be way off.
With that said, for the sake of fairness
““I just think that in particular what France2 did by putting out that big headline of the 7 watts/kg with a picture of Lance Armstrong, and I think Jan Ullrich, was so wildly wrong on so many levels. We thought we should correct that and give concrete facts and evidence, so hopefully people will judge for themselves. That’s what drove my decision,” Brailsford added.”
This is not really honest of him to say that. He speaks very good French, so I’m sure he understood what was said. Physiologist Sallet was interviewed and said that using ‘some mathematical models that are reliable and have been used for some time’ and with the data they have, they estimated his power at VO2max at 500w. That was based on an estimate of 425 for the climb, at 71kg. First, he wasn’t far in the power needed for the climb, especially since Froome is at a lower weight, and he said several times that 500w was his estimated power at VO2max, not for the ascension. The 7+ w/kg was his estimated power to weight ratio at VO2max also. The interview is available online (in French).
They never said that he sustained over 7w/kg for the climb. Never.
Yeah, most likely!
I am trying to tell from the photos available on the interweb if they were actually using Stages PM in stage 10. He was probably cycling harder with the other leg to be sneaky.
http://media.guim.co.uk/...2589/master/4317.jpg
(Posting link not image, because it is massive).
Read the wattage list. Placebo rings overestimate with SRM power meter because of the way SRM estimates power (avg. torque and angular velocity measured at frequencies rather than intervals in pedal stroke)
I’ve not seen it said that it’s the same with Stages or P2max or others.
See my post below. Not sure if stages or others (p2max, pioneer, garmin) over estimate. Just SRM
Also, it’s 2-6%, not “6”
Also, Froome could be 2kg lighter.
Worst case he could be at 6.2 w/kg (414/66)
Finally who knows if PM is calibrated
Not to mention digital EPO
Well, they can’t fudge the VAM. That’s elevation and clock data. So, the question is can 5.8 watts/kg produce 1602 VAM?Going up at 1600 VAM requires about 331W (mgv = 76 x 9.8 x 1600/3600). 5.8W/kg and a body weight of 68kg yields 394W so that leaves 63W (394 - 331) for aero and rolling resistance. I’ll leave the aero calcs to someone else.
VAM is probably more telling, if it can be validated. And as somebody said, take this in conjunction with the power numbers, see if it all stacks up. But yes, clouded if we don’t know accurately what he weighs. But the VAM figures quoted here are a bit lower than what we used to see in the EPO era, although historic data on that is a bit flaky, I gather.
No doubt be tonnes of analysis over the next few days.
I am not verifying the number, just directing the previous poster to the reason the number was present.
after races I like to go back and punch my numbers (weather, power, etc.), into bestbikesplit and compare it to my real world times. Based on recent results, the q-rings I use along with with a power2max suggest there is no boost in power for me (the 6% suggested above). The results are almost always very close to the bestbikesplit estimate. With that said, I might just be 6% more slippery than bestbike split knows about. who really knows?
I know this is bogus.
If you use precise and measured values for a climb, you might be pretty close. No way on random rides.