Cycling South Africa has confirmed mountainbike ace Burry Stander died in a crash in KwaZulu-Natal.
"He was returning from a training ride in Shelly Beach, on the KwaZulu-Natal south coast, and was hit by a vehicle," said the cycling body's spokesperson Mylene Loumeau on Thursday.
Police were investigating, according to the association.
Stander (25) was fifth in the men's cross country race at the 2012 London Olympics. Four years earlier, at the Beijing Games, he had proved his ability when he finished 15th in the cross country event at the age of 20.
The following season he rose to prominence on the global stage when he won the Under-23 title in the Mountainbike World Cup series. In 2011, Stander became the first South African to win the Cape Epic stage race in the Western Cape, with Swiss partner Christoph Sauser, and the pair defended their title in 2012.
"This is the saddest news I've received since I began my involvement in South African cycling 10 years ago. Burry was our brightest star," said Cape Epic founder Kevin Vermaak.
"I'm upset that the world has been deprived of a true legend in the making. Now we'll never know just how great he was destined to be."
Sauser posted a distraught message on Twitter, saying: "Never felt so empty since my dad passed away when I was a kid. @africanmtbkid I will never forget you."
Stander was married to elite road cyclist Cherise Taylor in May last year, just three months before he narrowly missed out on a medal at the London Olympics.
An emotional Loumeau said Stander, who was raised in KZN, would be missed by the South African cycling community.
"I had seen him come through the ranks since 2006," she said. "He was a fantastic role model, and at the same time he was humble at it."
Gideon Sam, the president of the South African Sports Confederation and Olympic Committee (Sascoc), said he was "shattered" by the death of Stander, a three-time national champion in his specialist discipline.
"Burry was the epitome of an Olympic athlete – talented, ultra-competitive but at the same time extremely humble and a true gentleman," Sam said.
"Sascoc, the cycling fraternity, and the entire South African sporting community mourns his passing and sends our prayers to his wife and family."
Sam said a concerted effort needed to be made to protect athletes using South Africa's roads.
"I've said this time and again but it is really time to work even harder at protecting both our runners and cyclists who use the roads daily to do their training." – Sapa