Danilo Wyss (BMC) led home the chase group at 55 seconds, with Sergey Lagutin (Katusha) in third. Conti's win is the first for an Italian rider in the race.
Quintana finished in the bunch 33 minutes and 54 seconds behind Conti to hold on to the red jersey. The Colombian continues to lead Chris Froome (Sky) by 54 seconds with Alejandro Valverde (Movistar) in third at 1-05.
In a complete change to the previous stage's frenetic pace from the gun, a 12-man escape group formed quickly at the start of the day and were allowed to stretch out an enormous 30-plus-minute lead over the peloton by the stage end.
The dozen escapees navigated the hilly stage – the longest of the 2016 race at 213.4km – slowly but surely extending their advantage over the bunch, which contained all of the GC contenders. Movistar sat at the front for Quintana, but there was visibly no urgency to chase with all 12 men up front well down the overall standings.
As the riders dipped over the border from Spain into France, the break retained its composure. It wasn't until the final 30km when Jelle Wallays (Lotto-Soudal) clipped off the front of the break, followed by Michael Gogl (Tinkoff), that the fight for the stage win commenced. Vegard Stake Laengen (IAM) spearheaded the chase to catch the duo, which was successful.
Conti then waited for an unclassified climb inside the final 19km to launch what would be the race winning move. Using his superior climbing power, he distanced the rest of the break and opened up a minute's gap leading into the finish at Urdax-Dantxarinea. Behind, a group of five chasers were left to scrap for the minor stage placings.
Lagutin had secured the lion's share of the mountains points over all of the day's four third category climbs, and took the lead from Quintana in the mountains classification for his efforts.
On Saturday, it's time for the general classification riders to come to the fore. Stage 14 goes for a longer excursion into France, a day of high mountains culminating in a final climb to the line atop the Col d'Aubisque. The gruelling 15km ascent will inevitably force a selection at the front of the race, and there will be no place to hide for any rider not in top form.
Vuelta a España 2016, stage 13: Bilbao to Urdax-Dantxarinea, 213.4km
1. Valerio Conti (Ita) Lampre-Merida in 5-29-04
2. Danilo Wyss (Sui) BMC Racing at 55 secs
3. Sergey Lagutin (Rus) Katusha
4. Michael Gogl (Aut) Tinkoff
5. Vegard Stake Laengen (Nor) IAM Cycling
6. Yves Lampaert (Bel) Etixx-QuickStep at same time
7. Cesare Benedetti (Ita) Bora-Argon 18 at 1-02
8. Jelle Wallays (Bel) Lotto-Soudal at 1-04
9. Gatis Smukulis (Lat) Astana at same time
10. Stephane Rossetto (Fra) Cofidis at 1-08
General classification after stage 13
1. Nairo Quintana (Col) Movistar
2. Chris Froome (GBr) Team Sky at 54 secs
3. Alejandro Valverde (Esp) Movistar at 1-05
4. Esteban Chaves (Col) Orica-BikeExchange at 2-34
5. Alberto Contador (Esp) Tinkoff at 3-08
6. Leopold König (Cze) Team Sky at 3-09
7. Simon Yates (GBr) Orica-BikeExchange at 3-25
8. Michele Scarponi (Ita) Astana at 3-34
9. David de la Cruz (Esp) Etixx-QuickStep at 3-45
10. Samuel Sanchez (Esp) BMC Racing at 3-56
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Nigel Wynn worked as associate editor on CyclingWeekly.com, he worked almost single-handedly on the Cycling Weekly website in its early days. His passion for cycling, his writing and his creativity, as well as his hard work and dedication, were the original driving force behind the website’s success. Without him, CyclingWeekly.com would certainly not exist on the size and scale that it enjoys today. Nigel sadly passed away, following a brave battle with a cancer-related illness, in 2018. He was a highly valued colleague, and more importantly, n exceptional person to work with - his presence is sorely missed.
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