SHOWS: MALLORCA, SPAIN (FILE - DECEMBER 2018) (TEAM SKY VNR - ACCESS ALL) 1.

GERAINT THOMAS TRAINING WITH SKY TEAM CARDIFF, WALES, UNITED KINGDOM (AUGUST 9, 2018) (BARN MEDIA - ACCESS ALL) 2.

THOMAS RIDING THROUGH CARDIFF AFTER WINNING THE 2018 TOUR DE FRANCE 3.

THOMAS SPEAKING ON STAGE 4.

THOMAS BEING INTERVIEWED PARIS, FRANCE (FILE JULY 2018) (REUTERS PICTURES - ACCESS ALL) (MUTE) 5.

STILL - THOMAS IN THE LEADER'S YELLOW JERSEY AND TEAM MATE CHRIS FROOME CROSSING THE FINISHING LINE TOGETHER AT THE END OF THE TOUR DE FRANCE 6.

STILL - THOMAS AND FROOME SHAKING HANDS ON THE PODIUM 7.

STILL - THOMAS CELEBRATING THE VICTORY WITH THE WELSH FLAG STORY: Tour de France champion Geraint Thomas crashed on the fourth stage of the Tour de Suisse on Tuesday (June 18) and abandoned the race, his team said, putting a question mark over his participation in the July 6-27 French race, the biggest in the cycling calendar.

"Geraint Thomas has been forced to abandon the Tour de Suisse.

He was alert and speaking to the team after the crash and will be taken to hospital for checks," his Team Ineos wrote on Twitter.

Ineos are already without four-time Tour de France champion Chris Froome for the three-week race around the country, after he suffered a heavy crash at the Criterium du Dauphine.

Thomas sat up after the crash and was moving both his arms. (Production: Jim Hatley)