If a bicycle pulls to one side when you ride it hands off, the fork is bent. Have a bike shop replace it. Once a year, or whenever the fork binds or clicks as you steer, inspect and grease the bearings. If any bearings are worn, pitted, or discolored, replace them all.
Each set of bearings rides between a cup and a cone. The balls may be loose or held in a frame called a cage. Tightening the upper cone will eliminate play in both sets of bearings. If the top cone is set too tight, the fork will bind and be hard to turn. Tightening the locknut may cause the cone to rotate too, requiring its readjustment (see Step 9).
1. Remove handlebar and temporarily hang bar on frame. Unscrew locknut, which may be either a hexagonal nut (left) or a slotted C-nut (right).
2. Lift off locknut and headlamp bracket (if any). You may then disconnect the cables to free handlebar completely or let bar remain hanging from frame.
3. Unscrew top bearing cone and remove upper bearings. Replace pitted or flattened bearings with a new set of the same size. Clean old grease from parts with kerosene.
4. Holding frame tightly to fork, lay bike on its side atop newspapers. Separate fork and frame, catching loose bearings in folds of paper. Clean cup and cone.
5. It bearings are not worn or dam aged, clean each set of them separately in kerosene. Dry them between the palms of your hands or in clean, lint-free toweling.
6. Fill the lower bearing cup with multipurpose grease, sold in bicycle shops. Press the correct number of bearings well into the grease so that they will not fall out.
7. Spread grease on bearing cone and lower the cycle frame over the fork column, being careful not to dislodge any of the bearings. Inspect and clean any balls that drop.
8. Partially fill top cup with bicycle grease and install upper bearings, taking care to install the right size and number of balls and not to drop or damage any of them.
9. Grease top cone and screw it on finger tight. Replace bracket and locknut. Adjust cone to eliminate all play. Tighten locknut; check for binding. Readjust if necessary.
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