Thomas will take aim at the Giro (May 5-28) for the first time in his career, sharing leadership duties of the British WorldTour team with Spaniard Mikel Landa.
Thomas has not raced the Giro d'Italia since 2012, and it will be the first time he has appeared in the Italian Grand Tour since he switched his focus from classics to stage racer last winter.
"It's interesting with 'G'," team boss David Brailsford told Cycling Weekly last winter. "He's ridden for Bradley [Wiggins], Chris [Froome] a lot. He's ridden so well. He's got all the attributes, all of the leadership skill that he's using already in the team."
Thomas's appearance at the Giro is a break from the routine of his recent seasons, where he has raced in the past four Tours de France and supported Chris Froome to three victories.
Speaking to the Evening Standard, Thomas said that when he eventually retires from the sport and turns up at his local pub in Cardiff, he can face his friends without regret that he didn't aim for a Grand Tour.
"I’d like to go in there and not be the grumpy guy in the corner and to say I gave it a go, I gave my all and I don’t regret anything. I don’t want to be the grumpy guy regretting this or that, that maybe I didn’t go for the podium in the Giro d’Italia in 2017."
Team Sky shifted gears last year with Thomas, who took aim at more stage races and limited his classics schedule. He won the Volta ao Algarve and Paris-Nice overall classifications. The only classics he took part in were Milan-San Remo and the Tour of Flanders.
His steady ride in the Tour de France earned him a 15th overall, backing up his same placing from 2015.
The 2017 Giro route should suit Thomas more than the Tour – The race features four summit finishes and more time trial kilometres, 67.2, than the Tour de France.
Thomas will face competition from defending Giro champion Vincenzo Nibali, backed by a new team at Bahrain-Merida, and rapidly emerging Grand Tour talent Esteban Chaves (Orica-Scott).
Landa led Sky during the 2016 Giro, but suffered stomach problems and abandoned the race. He won two summit finish stages and placed third overall in 2015.
Thomas and Sky kick off their WorldTour campaign at the 2017 Tour Down Under in Australia over January 17-22.
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