This article is about the Class III road numbered C109 maintained by DfI Roads. For other roads numbered C109, see C109.
The C109 forms a loop through the northern suburbs of Ballymena. The road starts at a roundabout on the A26 and follows Grove Road around the north of the town. Soon the road is intersected by the C60 (Doury Road) after which houses appear on both the inside and outside of the loop. The road crosses the A43 via a roundabout and continues eastwards as Frys Road. Following Frys Road, the road initially heads south east before suddenly swinging south west to meet the A42 at a roundabout near St Patrick's College.