Yes, you are basically correct. However, here is some more information.
Your rear wheel is composed of four parts: hub, sprocket carrier, spokes, and rim. The hub is the central component to which all other parts attach. Your RS3 bike has the same hub as our RX3 motorcycles in North America.
The sprocket carrier inserts into the left side of the hub, and connects the drive chain to the rear wheel. Your RS3 bike also has the same sprocket carrier as our RX3 motorcycles in North America.
The rim is the outer portion of the wheel which holds the inner tube and supports the tire. Your RS3 bike has a 15-inch rim, and our RX3 bikes have a 17-inch rim.
The spokes connect the rim to the hub. Your RS3 bike has shorter spokes than our RX3 motorcycles, since your 15-inch rim is smaller in diameter.
If you decide to build your own wheel, you need to buy a larger, 17-inch rim, and custom 17-inch spokes. Not every rim will fit; you need to select a rim which has the same number of spoke holes as your hub. Rims cost at least $100 USD, plus the cost of shipping. Custom spokes cost at least $110, plus the cost of shipping.
After you purchase the 17-inch rim and custom spokes, you will need to pay someone to disassemble your stock 15-inch wheel, and lace the larger rim to your stock hub. Therefore, if you exclude shipping charges, the cost of building your own wheel will probably exceed the cost of buying a new wheel from CSC.
It will cost more to ship an entire wheel from California to Malaysia. However, if you decide to build your own wheel, you will
still need to pay shipping charges for the custom spokes and rim. In addition, you will also need to spend time, and pay travel expenses, to visit the other city where the custom wheel will be built.
If you have further questions about building a custom rear wheel, please do start a new thread on this topic.
