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| No. 5 ~ NOVEMBER 03, 2001 | ||||
| Threadless
Headset Adjustment by Carlos |
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I'm going to limit this to threadless headsets since they are the most common these days. threadless simply means that there are no threads, on the steertube of the fork, for the headset to grip. in the case of a threadless headset, the headset only has one job, to provide a medium on which the front fork can turn. the gripping action is done by the stem and the adjustment is done by the top cap found on the top of the stem. many problems can occur from running a loose headset and the solutions can include everything from replacing a few bearings to replacing a whole frame. Before adjusting a headset, though, you'll need to know if the headset needs adjustment. there are many ways to do this so i'll only mention the easiest way i know. with the bike set on the ground, grab the front break with 3 or more fingers and depress the lever very firmly. while doing this rock the bike back and forth as opposed to up and down. if you accidentally compress the front fork, it will make it impossible to feel for play in the headset. so again, rock back and forth. if you feel a knocking sensation you may have a loose headset. i use the word "may" because several things can cause this sensation, they are: worn fork bushings, a loose QR on the front wheel, a loose hub, brakes with excessive play in the pivots, a loose handlebar, or loose stem. if you're not sure about any of the other factors mentioned, have the bike looked over by a mechanic at your favorite bike shop. On to the adjustment. this is very easy and usually doesn't take more than 15 minutes. ~start by loosening the stem bolts that clamp the stem to the steerer tube of the fork. ~once these stem bolts are loosened, you can use the bolt located in the center of the top cap to adjust the headset. the torque that you'll apply to the top cap bolt should never exceed the torque you would use to tighten the plastic cap on a milk jug. over tightening the top cap will crush the bearings or pit the raceways and lead to shortening of the headsets service life. a lack of sufficient headset spacers may prevent adjustment as well. make sure that there is a gap (refer to
pic below) between the top of the stem and the top of the steerer tube between 3 and 5 mm. headset spacers are available in heights from 1 mm to
10mm ~after the adjustment is made, snug down the stem bolts, grab the front brake, rock the bike back and forth, and feel for play in the headset. ~if the headset needs further adjustment make sure you loosen the stem bolts before making an adjustment. ~once all play is removed, tighten down the stem bolts and check for play one last time. |
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