MartinGT said:
So when someone says "Climbing speeds are lower" it means nothing due to the tactics, weather, what par cours, where the climbs are etc.
One has to take things with a pinch of salt, for the reasons you state, but there's not a huge variation from one year to the next in tactics, weather, route etc. So when one can observe with one's own stopwatch that the ascent of Alpe D'Huez in 2011 took the top guys 3-4 minutes longer (*), when they were racing seriously (**) than during the EPO years, one would be unwise to ignore the information.
(*) EPO years ascent times: 37:30 to 38:30 approx. In 2011, Rolland was fastest (~41 minutes) with Evans and the Schlecks ~42 minutes. Berto and SS were somewhere in between. For reference, the 2011 times are on a par with the fastest achieved in the late 1980s, though there are more riders in that range now than there was then.
(**) as evidenced by the state Contador (pedalling squares) and Franck S (slumped against barriers) at the end of the stage.
It should be noted that the 2011 ADH stages was unusual, being both short (110k) and subject to Berto's attack with 100k to go. These factors would work in opposite directions on the final climb speed, one would think. Short stage = good; fast early pace = bad.