Bearings allow a bicycle front wheel to spin smoothly around its axle. These bearings are housed on either side of the hub, which houses the wheel's axle. Bearings may become worn if their protective grease has dried out. The lack of grease causes the bearings to rub against one another, causing pitting on the surface of the bearing. Bearings are replaced with the wheel removed from the bicycle.
Lay the front bicycle wheel on a flat surface with the left, non-drive side face up.
Fit a 13-mm cone wrench to the cone. The cone is the "cone-shaped" nut between the side of the hub and the outer locknut.
Hold the 13-mm cone wrench and attach a crescent wrench to the outer locknut.
Rotate the crescent wrench counterclockwise against the 13-mm cone wrench, loosening the locknut.
Unthread the locknut, cone and any spacers the remainder of the way. Keeping these parts in order reduces potential confusion during reinstallation.
Lift the wheel and carefully slide the axle from the right side of the wheel.
Use tweezers to remove each of the bearings from both sides of the hub.
Use a rag to thoroughly clean each cup. The "cup" is the portion of the hub on which the bearings are seated.
Apply a layer of waterproof bicycle grease to each cup.
Press the new bearings into the grease. Replacement bearings must be identical in size and number to the old bearings. Cover the bearings with grease. Repeat for both sides of the hub.
Apply fresh grease to the axle threads and slide the axle through the right, drive side of the hub. Be careful not to dislodge any bearings.
Thread the spacers, cone and locknut back onto the left, non-drive side axle. Install these parts in the reverse order of removal. Tighten the locknut using just your fingers.
Lay the wheel down with the left, non-drive side face up. Attach the 13-mm cone wrench to the cone and the crescent wrench to the locknut.
Rotate the crescent wrench clockwise against the cone wrench, tightening the locknut further.
Hold the wheel up. Holding either end of the axle, shake the axle to check for play inside the hub. If there is lateral movement from the axle, continue to tighten the locknut.
Spin the wheel while holding both ends of the axle. The wheel should spin freely. If the wheel binds, loosen the locknut slightly.