However, fate intervened and his plans were derailed by a knee injury which prevented him from taking the start line in his home Island.
His sights were then adjusted on recovery and a ride at the Tour de France. He raced steadily if unspectacularly against Richie Porte (BMC) and Chris Froome (Sky) at the Critérium du Dauphiné to finish 5th overall, but to close watchers, the signs for a strong Tour performance was there.
“After the difficult moments I've gone through in recent months, it's fantastic to win a stage at the Tour de France. That was missing in my career," Aru said after taking the stage ahead of Dan Martin (Quick-Step Floors) and new race leader Chris Froome.
The 27-year-old is a somewhat mercurial rider often prone to explosion, but what cannot be denied is his attacking panache. You get the impression that with Aru, it's everything or nothing. Win, or die trying.
On Stage 5 it was a win and third place overall.
"I felt really good, so when we reached that point in a quite small group, I decided to go away," he said. "I did my all during these kilometers and I succeed. At the final kilometre I realized that I still have a good gap, so for the first time I started to believe I can do it till the end. "
His motivation on the 160.5km stage from Vittel to La planche des belles filles contained a bit of history. The performances of the man ahead of him on the general classification, Froome, and an absent compatriot, Vincenzo Nibali (Bahrain-Merida).
"When I got back on my bike after the injury that prevented me from riding the Giro starting in Sardinia, thinking of the Tour de France put a smile back on my face," he said.
"I never climbed to La Planche des belles filles before. I looked at the videos of Chris Froome winning in 2012 and Vincenzo Nibali in 2014. That's what convinced me to attack with 3km to go. I've always tried my best to deliver some spectacle to the fans.
"That was my intention today but giving spectacle and winning is an enormous satisfaction.”
The big question now for Aru is following through with an overall win. Something he's done once at the Vuelta a España in 2015 but has failed to do since.
"I have stage wins at the Giro and Vuelta, but I always wanted to take a victory here at the Tour de France. Last year gave me a lot in understanding of this race. And today this experience helped me a lot," he said.
His win on La Planche des belles filles now clearly marks him as an existential threat to the pre-race narrative of a Froome - Porte showdown. Both riders should be wary.
