Marcel Kittel says he's not surprised Tom Dumoulin wanted to leave Sunweb

Marcel Kittel has said Tom Dumoulin leaving Sunweb mid-season was "no surprise" to him.

The German raced with Dumoulin for four seasons from 2012 to 2015, when Sunweb was called Giant-Alpecin, and his final season with the WorldTour team was similarly marred by injury and a lack of form, just as Dumoulin's 2019 has been, with a crash in the early stages of the Giro d'Italia derailing his season.

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Kittel has placed the blame with Sunweb CEO and owner Iwan Spekenbrink, claiming he was good at bringing young riders through the ranks but couldn't fully unlock their potential as team leaders.

The 31-year-old says this applies to not only himself and Dumoulin, but also Warren Barguil and John Degenkolb. Barguil left the team in 2018 for Arkéa-Samsic, the season after taking the polka dot jersey at the Tour de France, and Degenkolb departed in 2017 for Trek-Segafredo having enjoyed his most successful season in 2015 when he won Paris-Roubaix and Milan - San Remo.

"That Dumoulin wanted to leave was no surprise to me," Kittel told In De Leiderstrui. "Spekenbrink forges a team for young riders and they are guided very well. But if riders become leaders then you have to give them some freedom. They apparently find that very difficult for the team.

"It started with me, but you saw the same problem arise with Warren Barguil and John Degenkolb. Then it was Tom."

Speaking on his own struggles with the team, Kittel relived his painful 2015 when he was plagued by a virus in the early season, struggling to finish races, before not being selected for the 2015 Tour de France. His transfer to Etixx - Quick-Step was then announced in October later that year.

"I suffered the most in 2015. I had renewed my contract after four stages in the Tour, but suddenly nothing worked. I had a lot of pressure that year. That eats on you, haunts you.

"I was depressed. Until the Tour, team boss Iwan Spekenbrink and I tried to find a solution, but it didn't work out. I no longer felt good with the team and applied for a contract termination in September. It started with Pfeiffer's disease, then we grew apart."

Kittel is currently enjoying retirement and preparing for the birth of his son, while also speaking openly about the mental health issues he dealt with during his professional career.

Dumoulin, meanwhile, is currently recovering from the knee injury that thwarted his 2019 season, and will race in 2020 at a Jumbo-Visma squad packed with GC talent, including Vuelta a España winner Primož Roglič and Steven Kruijswijk, who finished on the podium of this year's Tour.