Then explain this:
http://www.climbing-records.com/2014/07/impressive-ascent-times-on-pla-dadet.html
Pla d'Adet
2014:10,3 km@8,3%---30:32---average speed 20.24 km/h(Nibali-Peraud)
---31:50---average speed 19.41 km/h(Rafal Majka)
1982:10,4 km@8,3%---33:13---average speed 18.79 km/h(Beat Breu)
---33:48---average speed 18.46 km/h(Robert Alban)
---33:53---average speed 18.42 km/h(Alberto Fernandez)
---34:04---average speed 18.32 km/h(Bernard Vallet)
---34:05---average speed 18.31 km/h(Raymond Martin)
---34:06---average speed 18.30 km/h(Bernard Hinault)
---34:12---average speed 18.25 km/h(Joop Zoetemelk)
1981:10,4 km@8,3%---33:40---average speed 18.53 km/h(Lucien Van Impe)
---34:04---average speed 18.32 km/h(Sven-ake Nilsson)
---34:07---average speed 18.29 km/h(Hinault-Anderson)
---34:28---average speed 18.10 km/h(Jos De Schoenmaecker)
---34:33---average speed 18.06 km/h(Alberto Fernandez)
---34:33---average speed 18.06 km/h(Alban-Martin)
---34:43---average speed 17.97 km/h(Lucien Didier)
1978:10,4 km@8,3%---33:29---average speed 18.64 km/h(Mariano Martinez)
---33:34---average speed 18.59 km/h(Bernard Hinault)
---33:34---average speed 18.59 km/h(Michel Pollentier)
---33:48---average speed 18.46 km/h(Joop Zoetemelk)
---34:57---average speed 17.85 km/h(Joaquim Agostinho)
---34:58---average speed 17.85 km/h(Hennie Kuiper)
---35:50---average speed 17.41 km/h(Christian Seznec)
1974:10,4 km@8,3%---33:20---average speed 18.72 km/h(Raymond Poulidor)
---34:01---average speed 18.34 km/h(Vicente Lopez-Carril)
---34:22---average speed 18.16 km/h(Michel Pollentier)
---34:37---average speed 18.03 km/h(Alain Santy)
---35:09---average speed 17.75 km/h(Eddy Merckx)
---35:25---average speed 17.62 km/h(Wladimiro Panizza)
---35:54---average speed 17.38 km/h(Roger Pingeon)