Image 1 of 5 Chris Froome signs on (Image credit: Jayco Herald Sun Tour) Image 2 of 5 Team Sky's Chris Froome with Richie Porte (BMC) at the Cadel Evans Great Ocean Road Race in January (Image credit: Tim de Waele/TDWSport.com) Image 3 of 5 Chris Froome ahead of his short effort (Image credit: Jayco Herald Sun Tour) Image 4 of 5 Chris Froome out on the Romandie time trial course (Image credit: Tim de Waele/TDWSport.com) Image 5 of 5 Chris Froome and Alberto Contador ride to the line of stage 5 at Volta a Catalunya

Chris Froome has named Richie Porte (BMC Racing), Alberto Contador (Trek-Segafredo) and last year's runner-up Romain Bardet (AG2R La Mondiale) as his main contenders for the Tour de France. Froome did not, however, point to Nairo Quintana (Movistar), saying that the Colombian may suffer from the challenge of doing the Tour and the Giro d'Italia in the same season.

"My biggest threats come from guys who did not do the Giro, Richie Porte, Alberto Contador and Romain Bardet," Froome told Reuters. "I think it is going to be tough for Nairo to do the Giro and the Tour."

Quintana embarked on a Giro-Tour double attempt this season but fell short of the mark last month when he was beaten by Tom Dumoulin by just 31 seconds. Froome told Reuters that he did not see much of the Giro d'Italia due to altitude training in Tenerife, but admitted that Quintana could be in better shape come July.

"He may then be doing better on the Tour because he is a rider who is better in the second than the first grand tour," said Froome.

It is his former right-hand man Porte that has been the leading light of the general classification lot so far this season. Porte opened his account at the Tour Down Under, and despite a failed GC bid at Paris-Nice, he came home with a stage win. His last outing was the Tour de Romandie, where he beat Simon Yates to the title by 21 seconds. Froome suffered from back problems during Romandie, eventually finishing 18th overall.

"Richie has been amazing this season, winning the Tour Down Under and recently the Tour of Romandie. I think this year's Tour suits Richie really well," said Froome. "He's definitely got a chance to be up there for the win. This season he has been showing what he is capable of. I always believe in Richie."

Porte finished fifth in last year's Tour de France after losing time in the in the opening week due to a mechanical problem.

Without Porte behind him, Froome looks to Geraint Thomas and Wout Poels to be his last men in the mountains these days. Neither will be with Froome at the Criterium du Dauphine, which starts later this week. Thomas was given an opportunity to lead a Grand Tour for the first time at the Giro d'Italia. However, he left in the second week after injuries he sustained in a heavy crash on stage 9 to Blockhaus. Froome sympathises with his teammates but says that it could prove beneficial for the Tour de France.

"On the one hand, it was a huge setback for Geraint that he was not able to finish the Giro, but for the Tour, it will be only a good thing for the team because he will be fresher and have more time to prepare," he said.

After a lengthy spell training at altitude, Froome will begin the final stages of his Tour de France preparation at the Criterium du Dauphine. It has been a quiet season so far for the Team Sky rider, but he is happy with how things have panned out thus far.

"I think it has been a build-up similar to what I had last year. I think it worked well and I was able to do the Tour and the Vuelta," he said, adding that the Vuelta was not yet a certainty on his programme. "After the Tour, if everything goes well, I'd love to do the Vuelta."