For anywhere from 100 to 1000 baht, depending on the size of the bike, motorbikes can be rented in any beach town on Koh Samui. While the roads on Koh Samui are considerably better than those on other Thai islands (particularly neighboring Koh Phangan) renting a motorbike is a risky venture. In addition to the risk of injury, a common occurrence for foreigners on the island, there are occasionally scams involving rental motorbikes. As you must typically leave your passport as a deposit for a motorbike it is best to look for a reputable motorbike dealer even if the price is slightly higher.