A cyclist is in hospital after a passenger in a passing vehicle is believed to have leaned out and deliberately pushed him off his bike.
Dyfed-Powys Police are appealing for witnesses to the alleged attack at Hundred House, near Llandrindod Wells, on Saturday at about 1545 BST.
It is believed the man was taking part in a time trial on the A481 when he received a broken hip and collar bone.
People with information are urged to contact the Dyfed-Powys force on 101.
The man from Northwich, Cheshire, was taken to Hereford General Hospital.
Supt Huw Meredith of Dyfed-Powys Police said: "I would urge anyone who was in the area at the time who saw anything suspicious, or has any information about this incident, to contact police immediately".
People with information can call Dyfed-Powys Police on 101 or Crimestoppers, anonymously, on 0800 555111.