The main road along the west coast is paved and in decent shape, connecting all the major beaches from White Sand in the north to Bang Bao in the south. The road around the southern tip and up the east coast is also paved now, though steeper and quieter.
Songthaews (shared pickup trucks) run along the west coast and will pick you up or drop you off anywhere along the road. Agree on the price before you get in.
Renting a scooter is the most popular way to get around. The roads are hilly and have sharp curves, so take it easy, especially if you are not an experienced rider. Wear a helmet — accidents on Koh Chang's roads are common.