Steering Head Bearings - a bicycle maintenance guide

This article describes procedures to identify and correct common steering head bearing problems on everyday, ordinary bicycles. The procedures do not cover every related problem on every bicycle. The article is intended for adults with average mechanical ability, but assumes no previous bicycle repair experience. If you have any doubts that the procedures apply to your bicycle or of your ability to carry out the procedures, please consult with your local bicycle shop.

If your steering head bearings (or "head bearings") are well adjusted and in good condition, the front fork will turn from side to side smoothly, easily and quietly. The fork will not feel notchey while turning and will not rattle when braking or riding over bumps.

The head bearing outer races are pressed into the bicycle frame; inner races are fitted to the front fork "steering tube". The inner and outer races are separated by balls or rollers.

Head bearing problems include incorrect adjustment, lack of lubrication, wear and physical damage.

Checking head bearings

1. Raise the front wheel of the bicycle approximately 2" off of the ground. This is easiest using a bicycle stand (we sell them for under $14), but you can lift the front of the bicycle with one hand holding the top frame tube (or "top tube").
2. Grab the front wheel with your free hand and try to shake the wheel up and down. Listen for a knocking noise and look for movement between the front fork and lower head bearing. Also try this - with both wheels on the ground, apply the front brake and rock the bicycle forward and back. Look for movement at the upper head bearing between the steering stem and the frame.

Movement at the head bearings indicates looseness. See "Adjusting head bearings", below.

3. Check that cables or accessories will not interfere with turning the handlebars. With the front wheel raised 2", hold the handlebars with two fingers and slowly turn the fork back and forth through the steering centerpoint. The fork should move smoothly and with slight resistance. Once the fork is turning from the centerpoint, it should fall slowly to the side under its own weight, but should not flop over freely. There should be no sudden resistance or notchiness while turning near the centerpoint (a condition known as "indexing").

If the fork does not continue moving away from the centerpoint under its own weight, the head bearing adjustment is too tight. If the fork flops over freely, the head bearing adjustment is too loose.

Slight indexing can be caused by the head bearing adjustment too tight. Indexing can also be caused by head bearings that are worn or physically damaged. If adjusting the bearings does not correct indexing, confer with your local bicycle shop.

If the fork squeaks while turning, the head bearings may need regreasing. You can try spraying white lithium grease into the side of the head bearings, but if squeaking persists the fork must be removed and the bearing inspected. Removing the fork does not require a high degree of special skill or tooling, but it is beyond the scope of this article. If in doubt, visit your local bicycle shop.

There are two steering head bearing systems (called "headsets") in general use, threaded and threadless. Refer to both procedures to determine which type you have.

The fasteners and adjustment nuts for these procedures have standard right-hand threads; turning to the right (clockwise) makes things tighter, turning to the left (counter clockwise) makes things looser.

If you are unable to obtain a correct adjustment using one of these procedures, for safety's sake have your bicycle checked at the local bicycle shop.

Threaded headset adjustment

Tools required: headset wrenches of the correct size and type (an adjustable wrench is too thick, we sell headset wrenches for $9 to $15). You can use a brass or aluminum punch instead of a hook spanner for notched adjustment nuts.

Procedure

Note: Your bike may have a plate between the top lock nut and adjustment nut (e.g.; reflector mount, brake cable stop). The procedure is not effected but there will be limited access to the adjustment nut.

1. Loosen the top lock nut.
2. Tighten or loosen the adjustment nut, as indicated in the checking procedure. Make only a small change (less than 1/8 turn).
3. To prevent losing the setting, hold the adjustment nut against turning with the top lock nut. Tighten the top lock nut and recheck the head bearing using the Checking procedure.
4. Repeat until the adjustment is correct.

Tools required: Allen wrench - 4, 5 and/or 6 mm (we sell a set for $6)

Procedure

1. Loosen the clamp bolt(s) on the steering stem. Wiggle the steering stem left to right while holding the front wheel to loosen the clamp on the steering tube.
2. The top bolt adjusts the head bearings; it does not secure the steering stem. Overtightening the top bolt may pull the fastener out of the steering tube. Tighten or loosen the top bolt (maximum of 6 ft-lbs. tightening torque) to change the head bearing adjustment. In practice, you usually can tighten the top bolt to 5 ft-lbs and leave it at that.
3. Align the steering stem so the handlebars point straight ahead with the front wheel.
4. Tighten the steering stem clamp bolts and recheck the head bearing using the Checking procedure.
5. Repeat until the adjustment is correct.