THREADED HEADSETS Threaded headsets are adjusted using a top locknut and threaded adjusting race. The stem does not have to be removed to adjust the bearings, and can stay on the bike. The best bearing adjustment is to make the headset as loose as possible, but without bearing play or knocking. To do this, the following procedure will first create play in the adjustment, and then proceed to incrementally tighten the race adjustment until play is gone. 1. Use a headset wrench to hold lower race. 2. Using a large adjustable wrench or headset wrench, turn locknut counter-clockwise to loosen. Lower race is now free to turn. 3. By hand, turn lower race clockwise until it contacts ball bearings. Turn race back counter-clockwise at least 1/4 turn from this setting. Hold adjustable race with headset wrench and tighten locknut. Tighten locknut fully. This initial setting is intended to have play. 4. Check for play by pulling back and forth on fork. A knocking sensation indicates play. Turn the handlebars in different directions while checking for play. There should be play at this initial setting. If headset feels tight, loosen adjustment further until play is found. Use care with suspension forks, because the legs may have play in sliders. Grab upper portion of fork to help correct for this. 5. If play is present, grab front wheel between knees and hold it in line with top tube. Lower adjustable race will need to be adjusted SLIGHTLY clockwise. Use a wrench to hold lower race and note orientation of wrench. 6. Loosen locknut and move wrench holding adjustable race clockwise 1/32nd of a turn only. Do this in small increments. Front wheel must be kept straight to get proper adjustment. 7. Hold adjustable race from moving and tighten locknut fully. Check again for play, rotating fork and checking different positions. 8. If play is present, repeat steps "6" and "7" above until play disappears. Adjustment is finished when there is no play in any position as the fork rotates. OTHER: Another test of play is to place the bike on the ground and grab the front brake tightly. Press downward on the handlebars and rock the bike forward and back. A knocking sensation or wiggling may indicate a loose headset.. However, play in the brake caliper arms may also cause a knocking, so rule this out. Front suspension forks may also have play in the legs, which can cause a knocking. If the adjustment seems very tight after adjustment, there may be other problems in the headset. Bearing surfaces may be worn out, or the ball bearing retainers may be upside down, or a seal may be improperly aligned. You may need new parts… If play always seems present no matter the adjustment, the threaded steering column may be too long for the locknut, and need to be shortened. Add headset washers under the locknut in this case as needed. If this is not the problem, cups may be loose in their press fit in the frame, and need to be repressed. If you experience any difficulty with your headset, let a shop repair it!! ******************************************************** THREADLESS HEADSETS Threadless headsets work on a similar principal as threaded headsets. The bearing races press against the bearings. The bolt in the top cap will put pressure on the stem, which presses on washers below the stem, which press on the bearing races, which press against the bearings. All of this should be under the proper tension. NOTE: The cap and bolt at the top of the stem do not secure the stem onto the steering column, so don’t just tighten this randomly. The bolt or bolts on the side of the stem keep the stem from moving once the adjustment is made. The cap is used for bearing adjustment only. Remove the adjusting bolt in the center of the steering column, and remove the top cap. There may be a star-shaped nut or other fittings inside the steering column. The bolt threads into this fitting and pulls on the fork against the headset bearing surfaces, which acts to tighten the adjustment. Note the height of the steering column relative to the stem. It should be about 3-4mm (1/8") below the level of the stem. The stem needs to press down on the spacers properly in order to adjust the bearings. If the steering column is level with the top of the stem, another spacer is needed below the stem. 1.Remove bolt and top cap to inspect steering column. Lubricate adjusting bolt and re-install cap and bolt by hand only, do not over tighten. 2.Loosen stem bolt(s) that secure stem to the steering column. Lubricate these bolts if they are dry, but do not lubricate the stem! 3.Move the stem side to side to see that it is loose. If the stem is jammed or rusted frozen to the steering column, no adjustment can be made. 4.Align stem straight to wheel and gently secure the top bolt. Stop when any resistance is felt. 5.Tighten stem bolt(s). 6.Check for play by pulling back and forth on fork. Turn the handlebars in different directions while checking for play. There may be play at this early setting. Use care when grabbing suspension forks, because the legs may have play. Grab upper portion of fork. 7.To adjust bearings, loosen the stem bolt or bolts. 8.Turn adjusting bolt in center cap only 1/8th turn clockwise. 9.Secure stem bolts, check for play again. 10.Repeat adjustments as above until play disappears. Remember to loosen stem bolts before turning adjusting bolt in cap. 11.Check alignment of stem and tighten stem binder bolts fully. |
