[2] In the 1912 Summer Olympics, he competed in the Canadian men's eight boat but did not win a medal.

In 1907, Riddy joined the Toronto Argonauts, rowing in the winning fours boat in the Junior, Intermediate, and Senior Canadian Championship held in St. Catharines, Ontario.

Also in 1907, Riddy rowed in the winning senior four and eight boats at the U.S. Championship held in Philadelphia, Pennsylvania.

During 1909 and 1910, Riddy was the Argonauts Rowing captain, winning the club championship (The Hammond Cup).

Riddy was the oldest living Canadian Olympian when the 1976 Summer Olympic Games were held in Montreal, Quebec, Canada, though he was not invited to attend.