Giro d'Italia

The team entered the 2015 Giro d'Italia with Porte installed as team leader in the hope that he would continue his good run in stage races and claim the Maglia Rosa. In order to do this and in the team's quest for 'marginal gains' Porte slept in a motorhome which followed the race, rather than hotels like the rest of the team.^[12] After limiting the time loss in the stage 1 team time trial Elia Viviani secured the first win for the team in a Grand Tour since the 2013 Vuelta a España on stage 2, also taking over the Maglia rossa.^[13] After enjoying a successful first week Porte entered the second week of racing in third position overall, however on stage 10 an untimely puncture (outside of the 3 km ruling) caused him to lose 47 seconds to overall race leader, Alberto Contador.^[14] Porte was left isolated due to the puncture and accepted a wheel swap with Team Jayco–AlUla and close friend Simon Clarke, contravening UCI rule 12.1.040, which prohibits "non-regulation assistance to a rider from another team".^[15] Porte and Clarke were subsequently docked two minutes each and faced a 200 Swiss Franc fine.^[15] This resulted in Porte dropping down to 12th on the general classification, three minutes and nine seconds behind Contador.^[16] The implementation of the penalty caused outcry on social media; David Millar praised the sportsmanship shown between the two riders^[17] as well as Jonathan Vaughters, Chris Horner, Chris Boardman and Tom Domoulin.^[18] Team Principal, Dave Brailsford criticised the decision, saying that the "spirit of the law" had not been recognised^[19] and that there was a lack of common sense.^[20] Giro d'Italia race director Mauro Vegni claimed the rule had to be enforced^[21] whilst UCI President Brian Cookson agreed that it was the correct decision.^[22] Porte then lost further time on the uphill finish at Monte Berico on stage 12^[23] and a further two minutes on stage 13 after being caught behind a crash,^[24] leaving him in 17th spot, five minutes and five seconds behind new overall leader, Fabio Aru.^[25] Stage 14 saw the riders tackle the 59.4 km time trial from Treviso to Valdobbiadene, where Vasil Kiryienka claimed the stage win, whilst Porte conceded a further four minutes and six seconds to Contador, leaving him in 17th position, eight minutes and 52 seconds behind the race leader.^[26] On the next stage Porte lost a further 27 minutes and abandoned on the second rest day,^[27] team leadership being handed over to Leopold König.^[28] König would finish the Giro in sixth position, over ten minutes behind victor, Alberto Contador.

Tour de France

The team went into the 2015 Tour de France with their "strongest team ever"^[29] seeking to improve on their poor 2014 edition of the race. The team entered with Froome leading the title challenge, along with Poels, König, Kennaugh, Porte and Roche for the hillier stages as well as Stannard, Rowe and Thomas for the flatter days, in particular stage 4 from Seraing to Cambrai which featured no less than seven cobbled sectors.^[30] After a strong performance on the Mur de Huy Froome took over the race lead, and general classification by one second over Tony Martin. The previous time he had held the yellow jersey he won the race.^[31] Froome refused to wear the yellow jersey after Tony Martin abandoned the race due to a broken collar bone sustained on stage six.^[32] Froome then received the yellow jersey at the end of the seventh stage by virtue of being in second place overall. During the evening of the first rest day of the Tour, it emerged that some of Froome's data files had been hacked and released onto the internet.^[33] As the Tour entered the second week of racing stage 10 saw the first mountains stage, the summit finish of La Pierre-Saint-Martin, where Froome went on to take the stage win, putting significant time into his general classification rivals as well as Porte finishing second and Thomas finishing sixth.^[34] During the remainder of the race the team faced intense scrutiny regarding their dominant performances; Porte was punched in the ribs by a spectator in the Pyrenees,^[35] and Froome claimed he had urine thrown at him by another spectator,^[36] and blamed the incident on the French press for 'irresponsible' reporting^[37]

On the first rest of the Tour de France Porte confirmed he would leave the team at the end of the season.^[38] This would later, in August, be confirmed to be CCC Pro Team.^[39]

La Vuelta a España

On 10 August, Chris Froome announced his intention to compete in this years Vuelta a España,^[40] becoming only the second reigning Tour winner to ride the Vuelta in the same season.^[41]