26-year-old Australian cyclist James Williamson, who won the 2008 World Solo 24 hour mountain bike Championships in Canmore, Canada, died in his sleep on Tuesday while participating in the eight day, 723km Absa Cape Epic mountain bike race.
James, who edited the Australian Enduro mountain bike magazine, was declared dead at 6.47am in the Ceres Private Hospital, where he was taken when his riding partner Shaun Lewis, 28, could not wake him, the organisers said in a statement.
Describing Williamson as a "strong young athlete", the race organisers said he had an uneventful ride on Tuesday and had felt "completely well with no complaints" at the end of the stage.
"He and his partner ate well last night and everyone who spent the afternoon and evening with him said that he was perfectly fine. After the first two stages they were in 18th overall position."
Best wishes to his family.