Fabio Duarte (Colombia) was second at 17 seconds back, while Philip Deignan (Sky) was 37 ticks behind in third.
“After San Luis, where I won two stages, the Giro became my principal objective for the season,” Arredondo said of the Tour de San Luis, which Quintana won. “It’s going better than I could have dreamed. I have a stage, and I have the climber’s jersey. I am so happy. I still cannot believe it.”
Nairo Quintana (Movistar), who finished 10th at 2:46 back, stayed in the pink jersey and will ride in Friday’s 26.8K mountain time trial as the race leader. Rigoberto Uran (Omega Pharma-Quick Step) is 1:41 behind Quintana in second. Pierre Rolland (Europcar), who attacked the maglia rosa group late on the finishing climb, moved into third place at 3:29 back.
Cadel Evans (BMC Racing) struggled on the day and dropped from third to ninth in the GC standings and now sits 4:59 behind Quintana.
Final climb fireworks The ascent of Rifugo Panarotta saw some of the best bike racing of this Giro. With a large escape group riding off the front, the maglia rosa group containing the GC contenders and some of their teammates seemed content to let the breakaway stay right where it was.
At the base of the climb with 16K remaining, Thomas De Gendt (Omega Pharma) attacked the break and started a solo effort up the steep slope that featured gradients averaging 8.5 percent and as high as 14 percent.
Back in the peloton, Quintana was riding safely behind his teammates as both Movistar and Europcar controlled the pace on the lower sections of the mountain. Rolland, Evans, Uran, Ryder Hesjedal (Garmin-Sharp) and the other GC contenders were in the group as well.
Julian Arredondo came out on top after some of the Giro's best racing so far.
“It was a relatively calm climb, with plenty of attacks,” Quintana said. “Europcar was at the front, I controlled what was important to me, the others were fighting for what was important for them. My team was working well. Things went pretty well.”
At the front of the race, Ivan Basso (Cannondale) attacked the group chasing De Gendt with 11.5K remaining. His teeth gritted, it was clear the two-time Giro winner wanted to win the stage.
Shortly after, with De Gendt still in the lead, Dario Cataldo (Sky) broke free of the chasers and left them all -- including Basso -- in his wake. Cataldo was then joined by Deignan, Arredondo and Duarte. Franco Pellizotti (Androni Giocattoli) joined the foursome at the 7K mark.
With just over 6K to go, the chasers reached De Gendt. Arredondo then flew past him as if De Gendt was spinning on a bike trainer. Duarte matched the impressive effort and joined him, as did Deignan.
From that point, a series of attacks lit up the race. First it was Pellizotti, who surged ahead of the chasers and reached the leaders. He then went off the front, prompting a big effort by Arredondo to catch him. Arredondo reeled him in with 4.1K left and rode past. Duarte tried to match the effort and passed Pellizotti in an effort to reach his countryman up the road.
“Arredondo made a strong attack, and I couldn’t bring him back,” Duarte said. “He went very strong on the final climb. I wanted to win but it wasn’t possible.”
With just over 2.2K left and Arredondo riding away with the stage win, Rolland made his move in the maglia rosa group, which was around 3:00 back. Keeping it in the big chainring and the big rear cog, Rolland was turning the pedals hard as he distanced himself from Quintana, Uran and, more importantly, Evans.
Quintana, meanwhile, was still sitting up and looking comfortable in his pink kit, helmet, sunglasses and gloves. When it was clear Arredondo would win the stage as he passed under the flamme rouge, Duarte was still putting in a massive effort.
Fabio Aru (Astana) attacked the maglia rosa group with under a kilometer remaining, which forced Quintana and others to respond. Aru’s move paid off, as he gained three seconds on Quintana and moved from sixth to fourth in the GC.
“We wanted to control the stage today, so we were happy with how things go,” Quintana said. “Tomorrow is the time trial, and it’s a question of having the legs.”