Copyright Goodheart-Willcox Co., Inc. Motorcycles: Fundamentals, Service, Repair 330 Swingarm Axle nut Bearing spacer Hub Axle Wheel bearings Wheel hub Wheel bearing As axle is tightened, wheel bearings bind (no axle spacer). Axle Spacer Goodheart-Willcox Publisher Figure 16-7. A cast wheel is manufactured as one piece. Goodheart-Willcox Publisher Figure 16-8. The parts of this stamped scooter wheel are fastened together with bolts. Goodheart-Willcox Publisher Figure 16-9. The axle passes through the swingarm and wheel bearings. When the axle nut is tightened, the axle and wheel are locked into position. Goodheart-Willcox Publisher Figure 16-10. A spacer is needed between bearings to prevent side loading when the axle is tightened.