SERVICE YOUR BIKE’S HEADSET
Start by checking the current feel of the headset, so that you have a benchmark for any changes. Lift the front wheel off the ground and turn the handlebar. You’re looking for a smooth feel in the bearings. Any grittiness suggests the headset needs lubing or the bearings need replacing.
Remove the headset bolt and top cap, then slide the stem and spacers off the steerer tube. Put the spacers to one side, keeping them in the order you took them off. Lie the stem and bar on a stool or similar, so that the gear/dropper cables and brake hoses aren’t under strain.
Lift the head tube away from the fork and lie the fork/wheel down. The lower bearing will either drop out or will need prising out of the lower cup. Once removed, take time to clean the cups and the steerer tube.
Regrease the bearings and crown race (the washer at the bottom of the steerer tube). Add some fresh grease to the headset cups built into the frame, too, as this will help hold the bearings in place while you reinstall the fork. Refit the headset collar and replace the dust cap and remaining parts.
Loosen the bolts on the rear of the stem. These hold the stem tight to the steerer tube of the fork. Undo the headset bolt at the top of the stem. This runs between the headset top cap and the star-fangled nut in the steerer tube, and is used to tension the headset.
Hold the underside of the head tube and lift it off the fork crown so you can remove the upper headset assembly. Keep the parts in order so you know how to put them back. There’s generally a dust cover, a collar that sits snugly between the steerer tube and the upper bearing, and the bearing itself.
Run your finger inside the bearing to see whether the ‘race’ feels smooth and buttery. If it does, you can simply regrease and replace. If not, check the headset specs in the manufacturer’s tech docs or measure with a vernier calliper and headset gauge to find a replacement.
Tighten the headset bolt until it’s snug. Place the front wheel against a wall, hold the front brake and place your finger and thumb over the dust cap to see if it moves when you push the bike forwards. If it does, tighten a bit more. Finally, do up the rear stem bolts to the recommended torque setting.