(CNN) - Rohan Dennis' unexplained withdrawal from the Tour de France midway through the 12th stage has left the cycling world perplexed, with his team director saying he is "confused and disappointed" by the Australian's decision. "It was his decision today to stop at the feed zone," Bahrain Merida team director Gorazd Stangelj told reporters. When asked if Dennis' withdrawal was about his physical condition, his mental well being, or his dissatisfaction with his bike, Stangelj said he didn't think these were issues. The Bahrain Merida team initially released a message saying it was concerned for the "welfare" of its riders and would be launching an investigation into what happened to the 29-year-old Australian. "I am very disappointed to leave the race at this point," Dennis, who won the first stage of the Tour in 2015, told the Bahrain Merida website.