The cyclist, a 31-year-old man from Bracknell, was with his family at Allsmoor Pond in Harmans Water when he saw a man fishing between 1.30pm and 2pm.
The victim asked the man if he was a member of the club allowed to fish at the pond and was punched three times in the face, which caused minor injuries
The pair wrestled and the victim pushed the attacker off, who fell in the pond before leaving.
The attacker is about 6ft, thin, aged between late thirties and early forties.
His head was shaven and he had some tattoos and he was wearing green combat trousers and a beige t-shirt.
Anyone with information should contact PC Louise Grinney on 101 or call Crimestoppers anonymously on 0800 555 111.