Before you start replacing the belt on your upright bike, you will need to choose the right replacement belt. There are several types of belts available, including rubber, polyurethane, and Kevlar. The type of belt you choose will depend on your specific bike and riding style. Rubber belts are the most common and are suitable for most casual riders. Polyurethane belts are more durable and provide better grip but are also more expensive. Kevlar belts are the most durable and are ideal for high-performance riders.