Bardet, second in the 2016 Tour de France behind Chris Froome (Sky) and sixth in 2018, could not resist his home race after seeing the route announced.
"Until then, doubts remained," he told L'Equipe.
"But when I put the two race routes side by side, it was very clear. This is one of the first times I really saw the many opportunities available for our team.
"And as we know that the challenge of doubling Giro-Tour, playing for places on the podium, remains very difficult for me. I still prefer to focus on the Tour de France."
Bardet has never raced the Italian Grand Tour with so many mountain passes that could suit his climbing physique.
French and with a home team, the Tour de France is too big of a race to ignore. For the 2019 edition, announced in October, the organiser included a low amount of time trialling: 27 kilometres plus a 27-kilometre team time trial. The Giro d'Italia has 58.5 kilometres of time trials in 2019.
Dutchman Tom Dumoulin (Sunweb), second in the Giro and Tour this year, said that he is unsure about racing the Tour.
"There are several elements," Bardet continued. "The mountains come soon in the race with the Planche des Belles Filles [stage six], the time trial is quite early , there are seven passes over 2,000 metres, an Alpine triptych which will serve as the last battle, roads that I know very, very well, mythical arrivals like the Tourmalet..."
The French team will use Merckx bikes in 2019, another important aspect with the Grand Départ in Brussels, Eddy Merckx's city.
"It's nice that the Tour 2019 is a tribute to Eddy Merckx," Bardet added. "That gives extra motivation to put everything on the Tour. "
Sky's Chris Froome, the 2018 Giro winner, and Geraint Thomas, the Tour winner, have yet to announce their plans.
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