The German has been subject of strong rumours linking him to Trek-Segafredo in 2017 to head up their Classics team after Fabian Cancellara retires, having won both Milan-San Remo and Paris-Roubaix in his time with Giant.
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The 27-year-old has also taken 11 Grand Tour stage wins since joining the team after HTC folded in 2012, and came to the decision to leave after protracted talks with Giant’s bosses.
“This has been a tough decision,” Degenkolb said in a statement released by his agent on Friday, “but it has been a thorough and deliberate process to be sure we end up in the best possible situation.”
Watch: A day in the life at Giant-Alpecin
Degenkolb has only just worked his way back to full fitness, as he currently takes part in the Tour de France, having suffered serious injuries including a severed finger in a training ride collision with an on-coming car in January this year.
But despite not having appeared much this season, two teams appear to be in line to fight for his signature next season, with the deal set to be finalised by the end of the Tour.
“We have narrowed negotiations to two teams for next year and beyond,” the statement continued.
“My next contract will be about much more than money. Besides considering the best team fit, it will also be about image rights, my protection as a sportsman, and other details which have not historically been part of rider contract negotiations.”
No official announcement will be made until at least August 1, as per the UCI rules regarding transfers of riders.