MOTORCYCLE groups fear thousands of riders who will travel to Phillip Island for this weekend's motorcycle grand prix are at risk because of the many potholes on the major roads to the island.

Riders familiar with the roads of South Gippsland say they are in poor condition, including the Bass Highway to Melbourne, with many rough patches that are dangerous to motorbike riders.

Danger: A rider negotiates potholes on the Bass Highway. Thousands of motorcyclists will travel along the route to Phillip Island this weekend. Credit:Leigh Henningham

More than 100,000 people are expected to attend the three-day grand prix this weekend, with thousands of motorbike riders likely to make an annual pilgrimage to the island in huge convoys.

Rider Darren Impey, who commutes along the Bass Highway, said sections of the road were broken up between the towns of Koo Wee Rup and Anderson.