Contador, winner of all three grand tours, set a new Strava record over 3.29km, riding the distance in 15 minutes 01 seconds – one and a half minutes faster than the previous best time.
"Today, it was time to ride the famous Bola del Mundo climb," said Contador on Instagram.
"Luxurious day for the bike through Madrid's Range, today was time for the famous climb to 'The World Ball'. I've given a good squeeze with the 39x25!"
"I'd recommend a 34x30 gear ratio and better not to have so much tyre pressure, that way your tyres will skip less! By the way, the discs are appreciated in such a steep descent!"
The climb comes off the Navacerrada pass. The Bola del Mundo averages around 12 per cent and is said to include a 23 per cent section. The final 400 metres runs nearly straight and touches 16 per cent before reaching 2247 metres altitude.
The Vuelta a España brought the climb in the 2010 edition, when Vincenzo Nibali survived to win his first grand tour the next day. In 2012 it returned, again the penultimate climb before Contador won the next day in Madrid.
Exact climb time comparisons are hard to come by. In 2010, Spaniard Ezequiel Mosquera won the stage. He covered the final 3km in 12-53. His results in the Vuelta were later stripped for doping. In 2012, Joaquím Rodríguez had the fastest time, covering 3.4km in 13-29.
Contador won the 2012 Vuelta, one of the three editions he won. He won the Tour de France twice and the Giro d'Italia twice as well. He had one edition of the Tour and one of the Giro stripped due to a doping case.
The 35-year-old continues to ride and clearly stays in form. Contador isn't the first ex-pro to turn his attentions to Strava.
Since retiring, Phil Gaimon has been travelling to different climbs to set the KOMs, calling the challenge the "Worst Retirement Ever".
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