So, in terms of what that means for Wiggins and co at the front of the stage, it predicts about 6.4 to 6.5 W/kg. Over 16 minutes, that's not at all unreasonable. To give you some context, calculations of climbing power output in the Tour de France in the 1990s and 2000s often estimated that top riders maintained power outputs of 6.4 to 6.5W/kg on the Tour's HC climbs, most of which take over 40 minutes to climb. So in other words, there was an era where the best riders were maintaining similar power outputs to what we saw on Saturday, for three times the duration. Put differently, all those riders would probably have been a minute clear of this current generation on this climb...
Another point is the physiological implications of this performance. I try to explain this every year, but every year it seems to invite the (obvious) criticism, of which I'm well aware, that assumptions have to be made. Every year, I try to explain that if you control the assumptions, and make sure you always take "best case scenarios", you get a very clear and accurate picture of the physiological requirements behind a performance. So we'll try this again...
I've written before that I believe a sustained power output of above about 6.1 W/kg on the longer (40 min or more) climbs is not physiologically 'plausible'. I know that this is a view that Aldo Sassi shared (independently, I might add), and the reason for it is that to produce that kind of work, there are physiological requirements. Think of them as specifications in a car, and unless you have a certain engine, you can't achieve certain speeds. In cycling terms, the performances of 6.2 W/kg and higher simply cannot be met by any plausible combination of VO2max, cycling efficiency and thresholds. I describe this theory and the assumptions in this post from back in 2010.
Back to the 2012 race, the assumptions one might make for a 17 min climb are that a rider with efficiency 23% (high case assumption) can sustain 90% - 95% of maximal intensity for this short duration. Then, you can estimate that riding at 6.2W/kg (again, this is Brajkovic), the VO2 on the climb will be 77 ml/kg/min. Given the 90-95% of max estimate, this rider has a predicted VO2max between 81 ml/kg/min and 85 ml/kg/min (I realise there are 'errors' in the assumption, but I compare across generations to illustrate a point)
If you take lower case assumptions (efficiency of 24%, which I think is probably a more reasonable assumption), then the estimated VO2max falls to between 77 and 81 ml/kg/min.
Obviously, you can infer from these numbers what the implications are for the top 5 on the day, and you'll see that they're not too different. You're predicting physiology that says that the world's best cyclists have a VO2max of 85 to 87 ml/kg/min, that they're 23% efficient, and riding at 90% of maximum. Or, they could be 24% efficient with a VO2max of 81 ml/kg/min. That is, on paper, normal physiology for the best cyclists in the world in peak condition.
The "abnormal" physiology of years gone by came from guys who were sustaining 6.4W/kg for 45 minutes. That points to a human that has a VO2max of 97 ml/kg/min on the bike, or an efficiency of 28%, or can sustain 95% of max for 45 min at the end of five hours of racing. That just doesn't happen.
There's a risk of running away with physiological implications here. Let's simplify it into the obvious metrics - power and
time. The difference between the current era and previous eras is startling. In the last four years, none of the Tour's decisive HC climbs have been done at greater than 6 W/kg. Even the Contador-Schleck showdown on the Tormalet, with the Tour title at stake, was ridden at 5.9 W/kg.
