The 29-year-old Briton attacked key GC players Jai Hindley (Bora-Hansgrohe), Richard Carapaz (Ineos Grenadiers) and Vincenzo Nibali (Astana Qazaqstan) with just 5km to go to the finish in Turin opening an advantage of 15 seconds and holding it to the line.
It was a day of redemption for Yates, motivated to make up for the massive disappointment of losing 11 minutes on stage 9's Blockhaus climb last Sunday and falling out of GC contention.
Hindley outsprinted 2019 Giro champion Carapaz for second place on the day.
"I tried a few times in the beginning but it wasn't possible. I made a couple of moves but maybe the group was too big or I wasn't allowed to go, I don't know," Yates said.
"So we had to change tactic and to go after the stage normally. It was lucky that Bora tried to chase for the stage or for the GC. From there onwards I did my best.
"Not really. I mean not to put a downer on the day but I came here to win the race. For me it's another stage. I have five already and it's number six.
"I hope the legs stay as good as today. Today was a really big effort, not just for me but for everybody. The gaps are enormous, so if this heat sticks around it's going to be a very hard final week."
Carapaz had an excellent ride, having attacked on the Superga at 28km to go, eventually provoking the final, decisive splits in the lead group. He now leads the Giro d'Italia by seven seconds ahead of Hindley.
How it unfolded
Slated as of the most demanding, condensed stages of the Giro at 147km – with a stinging bonus of 3,000 metres of climbing – stage 14 was comparable to a high mountain stage, with all the chaos of a one-day race.
After the 7.7km neutral section through Santena, tension was already in the air as the flag dropped, marking the start of the stage. Never the one to follow convention, Mathieu Van Der Poel (Alpecin-Fenix) was the first to strike. Pascal Eenkhoorn (Jumbo-Visma) and Eduardo Sepúlveda (Drone Hopper-Androni Giocattoli) tried to bridge across, but Matthew Holmes (Lotto Soudal) dragged the peloton back up to the duo.
Rein Taaramäe (Intermarché-Wanty-Gobert) successfully joined forces with van der Poel, but the extra firepower wasn't enough to keep the two off the front, and both returned to the peloton at kilometre 133.
As teams continued to trade attacks, Nico Denz (Team DSM) took a tumble around one of the many corners of the technical route, adding to the bumpy 24 hours Team DSM has had at this Giro, with Cees Bol also abandoning before the start of the day.
Alessandro Covi (UAE Team Emirates), Alessandro Tonelli (Bardiani-CSF-Faizanè), Anthony Perez (Cofidis), Simone Ravanelli (Drone Hopper-Androni Giocattoli) and Oscar Riesebeek (Alpecin-Fenix) were the next riders to have a go. Still, there was no letup in the bunch, and the door closed on the move before they arrived at the first unclassified climb of the day.
The speeds remained high as the riders continued to fight for the breakaway, causing even the peloton to split at times. Another dangerous group containing a determined Yates and Chris Hamilton (Team DSM) formed before the start of the il Pilonetto – 6.4km kilometres long with an average of 5.4% – the first of five categorised climbs packed into the relatively short distance.
The lead changed hands as the attacks persisted on il Pilonetto. American Joe Dombrowski (Astana Qazaqstan) attacked in the final kilometre of the KOM and prompted Ignatas Konovalovas (Groupama-FDJ) to follow. The KOM leader, Diego Rosa (Eolo-Kometa), had to dig deep to come around both riders to add nine points to his lead in the king of the mountains competition.
The pace was all a bit too much for Tom Dumoulin (Jumbo-Visma), who called it a day at the top of il Pilonetto with 100km to go. The 2017 Giro d'Italia winner had been rumoured to be suffering from back issues and couldn't carry on.
On the descent off il Pilonetto, Dombrowski, Konovalovas, Rosa, Iván Ramiro Sosa (Movistar), Alessandro Covi (UAE Team Emirates), Nans Peters (AG2R Citroën), Ben Zwiehoff (Bora-Hansgrohe), Sylvain Moniquet (Lotto Soudal), Filippo Zana (Bardiani-CSF-Faizanè), Diego Andrés Camargo (EF Education-EasyPost), James Knox (QuickStep-AlphaVinyl), and Oscar Riesebeek (Alpecin-Fenix) built a gap of 40 seconds.
Bora-Hansgrohe take control
It was the first semblance of order in 60km, but it didn't take long for the Bora Hansgrohe trio of Wilco Kelderman, Emanuel Buchmann and Hindley to decimate the leaders' advantage, blowing the peloton apart in the process by the time they reached the second-category Superga climb.
Out of the GC riders, Alejandro Valverde (Movistar) was the one who struggled the most from Bora's tactics and eventually lost more than seven minutes in the overall classification.
With 65km to go, the situation in the front group was in constant flux, but most of the GC riders were there, including Juan Pedro López (Trek-Segafredo), Richard Carapaz (Ineos Grenadiers), João Almeida (UAE Team Emirates), Jai Hindley (Bora-Hansgrohe), Mikel Landa (Bahrain Victorious), Domenico Pozzovivo (Intermarchè-Wanty-Gobert), Emanuel Buchmann (Bora-Hansgrohe), Pello Bilbao (Bahrain Victorious), Wilco Kelderman (Bora-Hansgrohe), Vincenzo Nibali (Astana Qazaqstan), Jan Hirt (Intermarchè-Wanty-Gobert) and Simon Yates (BikeExchange-Jayco).
The leaders were 12 strong going over Superga and gained a 30-second advantage over chasers Dombrowski, Konovalovas and Guillaume Martin (Cofidis). The gap grew to a minute and 20 seconds by the time they reached the lower slopes of second-category Colle della Maddalena for the first time.
Kelderman, who started the day tenth overall 2:51 behind López, continued to drive the pace in what was left of the massively diminished peloton that contained the top 10 in GC, save for Valverde. Kelderman led the group over Colle della Maddelena first, collecting maximum points.
By the time the Bora trio led the front group into Turin for final circuit, they had a fairly comfortable three minute advantage on Dombroski, Martin and Konovalovas, who added Thymen Arensman (Team DSM), Lorenzo Fortunato (Eolo-Kometa), Santiago Buitrago (Bahrain Victorious), Diego Ulissi (UAE Team Emirates) and Filippo Zana (Bardiani-CSF-Faizanè) into the chase group.
With 32km to go, Kelderman pulled off, and Hindley immediately attacked on the lower slopes of second passage up Superga. Nibali also sensed the group was tired and pushed the pace to put Landa, Hirt, Pozzovivo and Bilbao on the back foot.
The group gradually reformed after the initial testing attacks from Hindley and Carapaz. Still, the pace was too much for the López, who dropped out of maglia rosa contention after a gutsy fight.
Just before the top of the climb, and with 28km still left to run, Carapaz launched a strong, yet risky attack and gained daylight on his rivals. The move put him into the virtual maglia rosa lead with less than 30km to go, but he still had to contend with a strong chase group containing two animated Bora-Hansgrohe riders, Buchmann and Hindley, and Bahrain Victorious teammates, Landa and Bilbao.
Carapaz crested Superga with a 20-second advantage on Almeida, Hindley, Landa, Pozzovivo, Buchmann, Bilbao, Nibali and Yates with the maglia rosa clearly on his mind. The Ecuadorian was, without a doubt, one of the strongest climbers in the race but still appeared nervous, looking back multiple times for a glimpse at his chasers on the descent.
Nibali went after Carapaz at the base of the final climb, taking Hindley with him on the steepest section of Colle della Maddalena. Hindley springboarded off Nibali's wheel and was the first to join Carapaz, Nibali and Yates, joining with one kilometre left to the top.
The four leaders had a slim 13 seconds on chasers Almeida and Pozzovivo starting the descent to the finish. Yates launched under the intermediate sprint point with five kilometres to go and had enough left in the tank to arrive in Turin the victor.
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A former professional and two-time cyclo-cross US national champion, Beard is also an award-winning journalist and cycling commentator. Since leaving competition, she has written for several major cycling media outlets, worked as media director for major US stage races and consulted with men's and women's professional cycling teams.