Replacing the Headset

If you're going to replace a headset "by the book," you should have a headset reaming and cutting tool, a headset press, and other weird stuff. In other words, you need a bike shop. But what the heck... Life's an adventure. And lots of bikers replace their headsets at home without disaster.

Good quality headsets have sealed bearings to keep out dirt. Replace your grit-laden old headset with one of these babies, and you're set for life. Headsets are sized to the fork's steerer tube:  the standard fork with a 1-1/8 inch steerer needs a 1-1/8 inch headset. A 1-inch fork needs a 1-inch headset.

Pieces of a headset.
Pieces of a headset.
What's in a headset: The fork crown race sits on the crown of the fork, holding the weight of the bike on the fork. The upper and lower cups hold the bearings that let the fork turn easily. The top cap and adjusting bolt determine how much the headset is compressed.
Taking off the top cap.
Taking off the top cap.
Banana Thunder has run through mud, snow, and rain for four winters. The bearings have been cleaned and repacked twice, but are no longer round. The headset rumbles when the fork is turned.

We're going to treat this old bike to a new sealed-bearing headset. First step, remove the adjusting bolt and top cap with a hex wrench.

Removing the stem.
Removing the stem.
Now we loosen the bolts on the stem. The stem should easily slide up and off the steering tube of the front fork. Be careful what you do with the handlebars -- the cable housing could get bent and trap the brake or shifter cables.
Dropping the fork out of the headset.
Dropping the fork out of the headset.
Now we drop the front fork out of the headset. In a non-sealed headset, there's a row of bearings between the top of the fork and the frame. Have a pan or clock under the fork to catch these bearings as the fork drops away from the frame.

If the fork won't go easily, place a piece of wood on top the steering tube and tap gently until it drops away.

Removing the top bearing cup.
Removing the top bearing cup.
Now remove the top cup. Lift the upper cover off the bearing cup. Using a pipe wrench, twist the cup until it turns free and comes out of the head tube of the bike.

(There aren't any threads. The bearing cup just sits in the tube, but it will be tightly stuck.)

Take out the bottom bearing cup in the same way.
Freeing up the crown race.
Freeing up the crown race.
Now get the old fork crown race off your front fork. Put a screwdriver on the underside, and gently tap the screwdriver with a hammer as you move the screwdriver around the crown race. Once it's loose, slide it off.
Installing the new crown bearing race.
Installing the new crown bearing race.
Install the new fork crown race from your headset. Slide it down, curved shiny side up. To seat it tightly at the bottom of the steerer tube against the fork's crown, use the old crown race as a "pusher." Turn the old crown race upside down, and slide it down against the new crown race. Tap down on the old crown race, moving around from side to side, until the new crown race is seated. Then remove the old race again.
Using a piece of wood and a mallet as a "headset press."
Using a piece of wood and a mallet as a "headset press."
This is where you really should have headset tools. But if the receiving hole in the frames head tube is smooth and round, and the fit of the new headset seems perfect, you can get by.

Apply a tad of grease to the first half-inch of the inside of the head tube, top and bottom. Slide the headset's bearing cup into the head tube. (Be sure you kept track of bottom versus top bearing cups.) Place a block of wood over the cup, and use a mallet or 2x4 to gently tap it into position.

Putting in the bottom bearing cup.
Putting in the bottom bearing cup.
Do the same thing for the bottom bearing cup. If you get into trouble here, you can destroy the new headset, so be careful!

Here's a nice method for getting the bearing cups into place: Get a large (such as 1/2 inch) threaded bolt, two nuts, and a large fat washer (or two) that's big enough to cover the bearing cup. Put one nut on the bolt, then the washer, then the second nut. Position the bolt so the big washer sits on the bearing cup, and tap the head of the bolt gently with your hammer until cup slides all the way into the head tube.

Lubing the bearing cartridges.
Lubing the bearing cartridges.
If you can't get the bearing cups seated properly into the headset, go to the bike shop.

Lube the bearing cartridges with heavy grease. Also lube the top surface of the fork crown race, and the treads of the headset adjusting bolt.

Putting the bearings into the bearing cups.
Putting the bearings into the bearing cups.
Install the bearings into the cups.
Inserting the steerer tube of the fork.
Inserting the steerer tube of the fork.
Slide the fork's steerer tube into the new headset. Make sure everything is seated properly.

Put the spacers (if any) back, and slide the stem onto the steerer. If necessary, replace the star nut (located inside the fork's steerer tube). If the headset has a different height than your old one, you may need to add or remove a spacer.

Tighten the top cap down BEFORE tightening the stem.
Tighten the top cap down BEFORE tightening the stem.
Put the top cap on. Screw in the adjusting bolt -- not tightly. Double-check the fit of the pieces. If it all works, tighten the adjusting bolt until it just begins to compress the headset: no up-and-down play, but no resistance to turning.

When the tension is right, tighten the stem back onto the steerer. Your fork should now turn Like Buttah!