Service & Repair Centre

Bristol's local bike shops since 1933

Loose Headset

Written by Mike Killa

Some modern bikes have sealed, non-adjustable headset bearings. All others require checking the adjustment even if they are sealed.

While the bike is on the floor, use two tests to check your headset adjustment. First, lift the front wheel off the ground by holding the top tube of the frame. If the headset is loose enough, the handlebar and front wheel will flop to one side or the other. Next, apply the front brake or hold the front wheel from turning, and push the bike back and forth an inch or two on the floor. A loose headset will click a little.

A headset which is loose will wear out soon. One which is already worn out will be gravelly or self-centering like an old-fashioned bar stool. This will impede safe steering. A headset which is too tight will also make steering difficult.

The headset adjusts like most bike bearings. There is an adjustable cup or cone at the top, and a locknut above that. By screwing the adjustable cone or cup closer to the bearings, the adjustment gets tighter. On many headsets there is an interlocking mechanism that means you will have to loosen the locknut several turns. On some there are two locknuts that must be loosened before you can make the adjustment. One may be hidden under a reflector bracket, or brake cable holder.

Two types of handlebar stems are in current use. The most modern type clamps around the top of the fork and is tightened with one or two allen head bolts. If you ride in all types of weather, the bolts should be removed, greased, and retightened. With any steel bolts that thread into aluminum alloy, a thin coating of grease is helpful years down the line, when corrosion would otherwise lock them together.

The older style is called a 'threaded stem,' and has an interesting design. In order to adjust the stem height, you must first loosen the top stem bolt two or three turns and then bang it down with a soft hammer. This releases an internal wedge. While the stem is loose, take it out and grease the shaft of the stem and the wedge threads. To reinstall, tighten the bolt once you are satisfied with the position. There must be at least 2-1/2 inches of handlebar stem inserted into the fork. Check to see that the stem is properly tight by trying to turn the handlebar while trapping the front wheel between your knees. Also check that the handlebar is secure in the stem.

Last Updated on Dec212020