Quintana begins the Volta a Valenciana stage race in Spain today with Team Sky and Orica-Scott's Yates twins, Adam and Simon.
Movistar confirmed his 2017 programme last week at the team presentation in Madrid. The 26-year-old Colombian – winner of the 2014 Giro and the 2016 Vuelta a España – will try to accomplish what no one has done since Marco Pantani won the double in 1998.
"Yes, that is a challenge. Complicated," Quintana told La Gazzetta dello Sport newspaper last week.
"Cycling is different today. I don't know if it's harder than before because I didn't live in that era, but it's different. The impression that I have is that the time differences at the end of a Grand Tour used to be more significant. Now, every day is a fight. Often stages are decided by seconds.
"For this reason, the double motivates me even more, it's a challenge that attracted us and we are accepting the 'risk' involved."
Alberto Contador (Trek-Segafredo) was one of the last stars to "risk" it and try to win both the Giro in May and the Tour in July of 2015. He succeeded in the first, but tired and up against a specifically-tuned Chris Froome, he placed fifth in the Tour.
"I'm wondering how much the Giro took out of him," Froome said in the 2015 Tour. "I really don't think it is the best preparation for the Tour. The best way to get ready for the Tour de France, in my opinion, wouldn't include doing the Giro d'Italia."
Contador, then 32, said that he was mentally fresh, but that his body was tired after the Giro.
Quintana believes it is possible based on his age and his fitness. He placed second in his first Tour in 2013, raced and won the Giro in 2014, and second in the Tour in 2015, he nearly toppled Froome on the final mountain finish on Alpe d'Huez.
In 2016, he focused on the Tour again. He appeared off, which the team said afterwards was partly due to allergies. He placed third and one month later, won the Vuelta in a tight battle with Froome.
"There'll be serious rivals, [Vincenzo] Nibali and [Fabio] Aru in Italy, and the usual Froome in France, but I think that we can take advantage of the moment, I'm speaking of age and form, and try to complete this complicated thing," Quintana added.
"The decision is from the heart. I won the Giro, which morally obligates me to participate in the 100th edition. It's a form of recognition for the big race that gave me my first big win.
"With the Tour we have a big debt that we have to pay off, both for the team and for me it's a very important race. We decided on the Giro based on emotions and the Tour due to the obligation."
The Giro, May 5 to 28, celebrates its 100th edition this year with a course that hits both big islands, Sardinia and Sicily, and travels south to north with the usual big mountain final week.
The Tour starts 33 days afterwards with rivals like Froome, Romain Bardet (Ag2r La Mondiale) and Richie Porte (BMC Racing) preparing specifically for the race.
"The Giro is hard, I can't start with a big load of racing otherwise I'll risk also compromising the Tour," Quintana said.
"You need to know how to recuperate [in between], how to manage the transition, profiting from the full month that separates the two races."
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