This year's Post TT Road Races have been cancelled, due to the postponement of the Senior TT.
Organisers say many officials, marshals and other personnel involved are also needed for duty on the Mountain Course and may not be available later for the Billown Course.
Road closures also mean they wouldn't necessarily have full medical or marshal cover.
Southern 100 Racing has apologised to all competitors.
Stop falsely accusing youngsters of vandalising skate park!
Plans to make northern school more accessible
Government fully committed to min wage rise
Airport director apologises for 'unusual circumstances' which returned flight
Garage staff get body cams to tackle abuse and theft
Manxman expected in Heysham around midday, says Steam Packet
Carbon literacy training is for legal requirements, says DEFA
Manxman returns to port following medical emergency