How to fit and adjust a headset on a road bike

First of all, here are the steps for correctly assembling a headset.

Slide the lower bearing over the steerer tube and onto the top of the fork. The tapered face on the inner race of the bearing is designed to fit onto the angle that is tapered onto the top of the fork.

If the bearing doesn’t fit onto the top of the fork, you may have inserted the bearing the wrong way round.

Slide the steerer tube through the bottom of the head tube. Once fully inserted, the lower bearing at the top of the fork should slot into the bottom of the head tube.

Slide the upper bearing over the steerer tube and place it into the top of the head tube. The bearing needs to be inserted the correct way round and should sit flush inside the top of the head tube.

Slide the collar/compression ring onto the top of the bearing and then add the bearing top cap.

This sits on top of the bearing to provide another layer of protection.

Insert the spacers over the steerer tube. These will affect how high the handlebars are, so make sure you use the correct number.

Once you’re happy, slide the stem onto the steerer tube, but don’t tighten the bolts yet.

Regardless of whether you decided to use lots of spacers or none at all, you need to make sure there are enough spacers covering the steerer tube, with an excess of about five millimetres on the top. This is so you can tension the headset correctly in the next step.

Presuming the expander plug or star nut are already in place, attach the top cap and bolt and secure everything together to the recommended torque limit. Getting the torque right is important. The top cap applies preload to the whole system, removing any unwanted play in the bearings. You want the fork to turn freely and smoothly in the frame, but any movement in the collar of the headset suggests the system is too loose.

Finish by securing the stem clamping bolts, but be careful not to exceed the recommended torque limits. This will usually be indicated near the bolts on the bike or can be found in the bike’s handbook.

If your headset is already assembled, you may need to make some adjustments to remove any play.

You can identify if there is any play in your headset by holding the front brake lever and rocking the bike backwards and forwards, with the stem bolts loose. Hold the bike around the bearings to feel for any play and listen as it will sometimes make a small knocking sound.

If there is any play, it will often only require small adjustments.

Usually, there will be play because the top cap bolt isn’t tight enough.

With the stem bolts loose, use an allen key to further tighten the top cap bolt. Only tighten it incrementally, checking each time to see if it has removed the play. Be careful not to exceed the recommended torque limit.

If there is still play once you’ve reached the torque limit, there may be another issue. Here's how to resolve the most common issues:

Make sure that you secure the top cap before tightening the stem bolts, otherwise it won’t be able to preload the headset.

Double check everything was correctly assembled. You may have placed a bearing the wrong way round.

If everything is assembled correctly and you’ve followed the above process, the play may be caused by worn bearings which may need replacing.

If the bearings aren’t the problem and the headset appears to be assembled correctly, it’s best to take your bike to a local bike shop for further investigation.