Check out the main contenders at this year's Tour de France

Chris Froome may look far from his best and might say this year's route does him no favours, but the Briton is the overwhelming favourite to win his fourth Tour de France crown next month.

His main rivals - an ageing Alberto Contador, a too-cautious Nairo Quintana and an unreliable Richie Porte - all seem short of the combination of ingredients needed to unsettle Froome's Team Sky machine, and Romain Bardet looks a little green to become France's first Tour champion since 1985.

Other contenders include Italian Fabio Aru, Dane Jakob Fuglsang and Ireland's Dan Martin.

The race starts in Germany on July 1 with a 14-km (8-mile) time trial in Duesseldorf, where local rider Tony Martin will be one of the favourites to claim the first yellow jersey.

That would serve as a powerful symbol in a country that has shunned the race for many years in the wake of doping scandals and only resumed televising it in 2015.

A look at the main Tour de France contenders ahead of Saturday's first stage, a 14-km individual time trial in Duesseldorf:

Chris Froome (Team Sky)

Nationality: British

Age: 32

Notable grand tour results - Tour de France: 1st (2013, 2015, 2016), 2nd (2012); Vuelta: 2nd (2011, 2014, 2016)

Froome is the overwhelming favourite for the race as he will once again have the support of the strongest team. In recent years Sky have controlled the race, sustaining a fast pace in the climbs to prevent attacks from rivals, with Froome usually finishing the job at the end of each stage. Last year, the Briton showed he was able to attack on all terrains, dropping his rivals in descents or on the flat.

There is, however, a slight concern over his form as Froome has not won a race this season, unlike the victories he celebrated in the build-up to his previous victorious Tour rides. He seemed to lack some form during the pre-Tour Criterium du Dauphine. But his experience should make the difference even if the treacherous route this year, with very little time-trial mileage, will not favour Team Sky.

Richie Porte (BMC Racing)

Nationality: Australian

Age: 32

Notable grand tour results - Tour de France: 5th (2016); Giro d'Italia: 7th (2010)

Porte has been the most impressive stage-race rider this season, winning the Tour Down Under and the Tour de Romandie before taking second place in the Criterium du Dauphine. He looked in top shape on the climbs.

Porte's track record in grands tours is, however, rather poor. He often suffers an off day that kills his chances and may not fare well in the most chaotic stages in this year's race.

Nairo Quintana (Movistar)

Nationality: Colombian

Age: 27

Notable grand tour results - Tour de France: 2nd (2013, 2015), 3rd (2016); Giro d'Italia: 1st (2014), 2nd (2017); Vuelta: 1st (2016), 4th (2015)

One of the best climbers in the world and one of very few able to drop Froome in the mountains. The lack of time trials this year will play in his favour.

But having ridden the Giro d'Italia, Quintana might struggle to keep his form during the three weeks of the Tour. He has also shown in previous editions that he is quickly happy to settle for second or third.

Romain Bardet (AG2R-La Mondiale)

Nationality: French

Age: 26

Notable grand tour results - Tour de France: 2nd (2016), 6th (2014)

Had a difficult start to the season, being kicked out of Paris-Nice for taking a team car tow, which forced him to change his schedule.

The French climber, second overall last year, has however improved and the route, with several stages suitable to his swashbuckling style, could help him challenge Froome.

Alberto Contador (Trek-Segafredo)

Nationality: Spanish

Age: 34

Notable grand tour results - Tour de France: 1st (2007, 2009); Giro d'Italia: 1st (2008, 2015), Vuelta: 1st (2008, 2012, 2014)

Contador's last Tour title dates back to 2009 and while he certainly does not have the same condition, the Spanish daredevil still has the spark. He is feared by all his rivals for his ability to launch long-range attacks.

Has made the Tour his only goal of the season.

Fabio Aru (Astana)

Nationality: Italian

Age: 26

Notable grand tour results - Giro d'Italia: 2nd (2015), 3rd (2014); Vuelta: 1st (2015)

A very good, aggressive climber, Aru will lead Astana during the Tour for the first time and can hope for a decent result. His lack of Tour de France experience could prevent him from challenging Froome all the way to Paris, though.

Jakob Fuglsang (Astana)

Nationality: Danish

Age: 32

Notable grand tour results - Tour de France: 7th (2013)

The rider of the moment. Fuglsang beat Porte to win the Criterium du Dauphine thanks to an impressive attack in the final stage.

He may have peaked too soon, however, and may find himself having to work for teammate Fabio Aru.

Alejandro Valverde (Movistar)

Nationality (Spanish)

Age: 37

Notable grand tour results - Tour de France: 3rd (2015), Giro d'Italia: 3rd (2016), Vuelta: 1st (2009), 2nd (2006, 2012), 3rd (2003, 2013, 2014)

After an ominous start to the season with titles in the Fleche Wallonne and Liege-Bastogne-Liege classics, victories in the Tour of Catalunya, Tour of the Basque Country and Tour of Andalucia, Valverde took some time off and came back for the Dauphine. He launched long-range attacks but failed to unsettle the best. A potential podium finisher in Paris even if Quintana is expected to be the team leader.

Photographs: Getty Images