in the 90s and 2000s, the data say that the best climbers were regularly riding at 6.5W/kg or even higher on the long HC climbs at the end of stages. The goal that riders then set for themselves was based on what they were able to observe in the race, when men like Riis, Pantani, Ullrich, Armstrong were going up Alp d'Huez in under 39 minutes, corresponding to around 6.3 to 6.7W/kg.
Since the biological passport has been introduced, that power output has dropped considerably, and in the last 4 years (the
time where I've been documenting the climbing power), the highest I've seen was Contador vs Schleck on the Tormalet where they rode at about 5.9W/kg.
SO I think the new target is probably 6W/kg. Obviously, on a shorter climb (20 min) they can go higher (6.5W/kg), and of course if a climber is fresh, they'll go higher, but at the end of a 4 hour stage, to hit a 30 to 45 min climb at 6.5W/kg just does not happen. Also, the physiological implications of this kind of power output are just not plausible. There is not a combination of physiology that would allow this effort, whereas 6W/kg points to a guy with a high VO2max, high efficiency, so I thin these are all good signs for the sport.
They don't prove that it is clean, of course, but they do suggest that it's better than ever. The emphasis now shifts to catching the micro-dosing that the riders might use to help them recover better, because the other thing that factors into all this is the ability to do this every day for 3 weeks!