Gold medal-winning cyclist Simon Richardson, 44, was airlifted to hospital after a hit-and-run incident with a van yesterday morning.
The cyclist was thrown from his bike after a crash on the A48 outside Bridgend.
Police said he was apparently struck by a van travelling in the same direction.
A 59-year-old man from the Cowbridge area has been arrested. Police are appealing for witnesses to the incident.
Mr Richardson was left disabled after a serious car accident in 2001, with no feeling on the left side of his body.
He took up cycling again in 2005 on a specially-adapted bike powered by his right leg.
He won two cycling gold medals and one silver in the Beijing Games in 2008.
He received an MBE in 2009.