Motorcycle wheel bearings can last a very long time depending on how you take care of them. With proper maintenance the bearings will stay in good shape. If you are constantly running your bike through water and debris, you increase the chances of getting water and debris in the bearings. This is when the bearing life starts to shorten. Water and debris combined with the rotation of the wheel will wear out the bearings. This is why keeping your bearings properly greased while avoiding water and debris will allow the bearings to function properly and last a long time.