The Belgian had said his status in the team had "increased enormously" when he turned down advances from other teams to extend his contract with Bahrain McLaren earlier this month.
However, he has been overlooked for the Tour in a team that is built around Mikel Landa but also sees support for sprinter Sonny Colbrelli, who was preferred to Mark Cavendish. Pello Bilbao, Wout Poels, Damiano Caruso, and Rafael Valls will support Landa, while Marco Haller is there for Colbrelli and Matej Mohoric rounds out the squad.
Teuns, who won a stage of last year's Tour on La Planche des Belles Filles, suggested his performance at the Critérium du Dauphiné, where he finished 91st overall, led to the decision.
"I got a phone call on Tuesday. [Team manager] Rod Ellingworth informed me that I will not be with the Tour. I appreciate that he called me personally to share the news. He also finds it very annoying himself," Teuns told Het Nieuwsblad.
"The team indicates that I rode a lesser Dauphiné. The fact that I had problems with my back apparently did not contribute to the decision. I am of course very disappointed."
Teuns had previously indicated he was fully invested in going to the Tour to support Landa's bid for the overall title, while also taking any opportunities for himself when they arose.
However, he now as to adjust his plans and turn his focus to the Classics in October after Tirreno-Adriatico in the second week of September. He could still ride a Grand Tour in the form of the Vuelta a España but it starts just two days after the Tour of Flanders
"It's not nice that I'm not allowed to come along now. It is not a good start to the second half of the season, but I do not gain anything by crying in a corner.
"Hopefully the races can be held in the last months of the season. The Classics are then the big goal. I have very few race days this year and so there are few opportunities to show yourself. After the Dauphiné there was no Belgian Championship to prove that I am in shape. A great pity, because I could certainly have been valuable to Landa."
Bahrain McLaren made no specific mention of Teuns or Cavendish in their Tour announcement but Ellingworth gave an explanation for the general selection.
"This year's parcours is very well suited to Mikel, and his form is strong. The group we have chosen to support him represents our riders who are most suited to the parcours and Tour-ready," he said.
"The past few months have been challenging for all riders to be race fit, and it’s a credit to all of our guys that we had such a strong line-up to choose from."
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