The Kirirom Mountain Challenge makes its annual return to the Kampong Speu national park this Sunday with more than 200 cyclists expected to participate in nine separate classes of age and ability.

Races will start at 8:45am and wrap up at 3pm. Registration varies between $5-$20 and can be made up until Wednesday at Flying Bikes 2 shop (St 51, No 131 ). Organisers say more than $3,000 of cash and prizes are up for grabs.