The original course start line was situated near Loanends Primary School on the secondary B39 Antrim to Belfast Road.

The Clady Circuit was shortened in 1947 to a length of 16.467 mi (26.501 km) with the omission of the Aldergrove section from Thorn Cottage to Greenmount.

The lap record for the short Clady Circuit is 9 Minutes and 21 seconds at an average speed of 105.94 mph (170.49 km/h) set by Les Graham riding a 500cc MV Agusta 4C during the 1952 Ulster Grand Prix.

The lap record for the 1922–1939 Clady Circuit is 12 minutes and 17.8 seconds at an average speed of 100.03 mph (160.98 km/h) by Dorino Serafini riding a 500cc Gilera motor-cycle during the 1939 Ulster Grand Prix.

The race record for the short Clady Circuit is an average speed of 99.79 mph (160.60 km/h) set by Cromie McCandless riding a 500cc Gilera also during the 1952 Ulster Grand Prix.