Overhauling your headset

If adjustments don’t alleviate looseness or other issues with the headset, you may need to overhaul it. Headsets can take a lot of abuse, especially if you ride on challenging terrain or in bad weather, so an overhaul that replaces bearings and packs them in fresh grease can go a long way toward improving and extending the life of your bike’s steering system.

Threadless headsets

Overhauling a threadless headset is sometimes easier if you remove the han­dlebars. Do this by removing the bolts in the stem that hold the handlebars in place. It also helps to remove the front wheel from the fork (see Chapter 7). Depending on what type of brakes you have, you may need to remove these as well (see Chapter 8).

Here’s how to overhaul a threadless headset:

1. Using an Allen wrench, unscrew and remove the bolt and top cap in the top of the stem (as shown in Figure 15-11).

2. Loosen the clamp bolt or bolts holding the stem in place (see Figure 15-12).

Be sure to keep a hand on the fork if your bike is off the ground.

3. Slide the stem off the fork steering tube (as shown in Figure 15-13).

As you do this, make sure you hold onto the fork so that it doesn’t fall on the ground.

4. Remove the parts of the headset, including any washers or spacers (as shown in Figure 15-14).

Keep track of the order in which you remove things so you can put everything back together more easily.

5. Pull the fork out of the frame (as shown in Figure 15-15).

If the fork is stuck, you may have to tap it with a mallet, being careful not to damage the top of the steering tube.

Figure 15-12: Undoing the clamp bolt.

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Figure 15-13: Removing the stem.

Figure 15-14: Removing spacers.

6. Remove the bearings (see Figure 15-16).

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There is a top and bottom or an inside and outside of the bearing race. Take note of the bearing race positioning before removing the bearings. If you don’t reinstall them properly, you won’t be able to adjust the headset and you’ll damage both the bearings and the headset.

7. The bearings will likely be contained in a race with their surfaces exposed or sealed in a cartridge (see Figure 15-17 for both types):

• If the bearings are exposed, inspect them. Bearings that are pitted or do not have a shiny surface should be replaced.

• If your bearings are sealed in a cartridge, check to see that they turn smoothly. If they don’t, replace them.

8. Clean and inspect all parts.

9. When you’re ready to reinstall the headset, coat both cups with a

layer of grease.

10.

Insert one of the races into the bottom cup.

11. While holding the bottom race into place with one hand, insert the fork with the other hand.

This procedure is sometimes easier if you turn the bike over.

12. When the fork is inside the head tube, slide the other race over the fork steering tube and down into the top cup of the head tube.

13. Slide any washers or spacers over the fork steering tube in their original order.

Figure 15-16: Bearings in the headset.

Figure 15-17: Two styles of bearings.

14. Attach the top cap and screw it into place with the Allen bolt.

15. Follow the procedure for headset adjustment in the “Threadless headsets” section under “Adjusting your headset.”

16. Center the stem and secure it by tightening the clamp bolt or bolts.

If you replace a headset with the same model, you’ll be able to install it your­self in most cases — you won’t have to press the head-tube cups into the frame because you can reuse the ones currently in place. However, if you change headsets, you’ll need your local bike shop to install it. Special tools along with skill and expertise are required for removing headset parts from a bike frame and installing new ones.

Threaded headsets

When you overhaul a threaded headset, you’ll likely observe the reason for its name — the threaded steerer tube that sits at the top of a fork. You’ll also see that a threaded headset is unique with its expander bolt, something that helps keep it in place when tightened.

To overhaul a threaded headset, follow these steps:

1. Use an Allen wrench, or adjustable wrench if needed, to loosen the socket head bolt, which sits at the top of the stem.

Turn it just a few times to loosen it. Do not completely remove this bolt. It’s connected to an expander wedge at the bottom of the stem, which keeps the stem in place. Sometimes the bolt may be buried deep inside the stem and require a longer Allen wrench (see Figure 15-18).

2. After the bolt is loosened, place a small block of wood on it and give it a firm blow with a hammer to jar the wedge loose.

If the stem has not been removed for a while it may take more than one blow and/or some penetrating lubricant.

Figure 15-18: Loosening the socket head bolt.

3. Lift the stem out of the steering tube connected to the fork (as shown in Figure 15-19).

4. Remove the headset locknut by turning it in a counterclockwise direction (as shown in Figure 15-20).

5. Slide off any washers or anything else that sits underneath the locknut you just removed.

6. Unscrew the adjustable cup or cone that sits against the top of the head tube.

As you do, hold on to the fork with one hand so that it doesn’t fall to the ground.

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There is a top and bottom or an inside and outside of the bearing race. Take note of the bearing race positioning before removing it. If you don’t reinstall it properly, you won’t be able to adjust the headset and you’ll damage the bearings and the headset.

Be careful with the bearings that sit in the top and bottom of the head tube. If they’re contained within a race, you’re in good shape; if they’re loose, they may fall out when you remove the adjustable cup or slide out of the fork. In the case of loose bearings, remove the top set before you slide out the fork. Then turn the bike upside down to remove the fork and the bottom set.

7. Inspect the bearings to see if they’re pitted or worn.

If they are, they should be replaced.

8. Clean and inspect all parts.

9. When you’re ready to reinstall the headset, coat both cups with a layer of grease.

10. Insert one of the retainers into the bottom cup.

11. While holding the bottom retainer into place with one hand, insert the fork with the other hand.

This procedure is sometimes easier if you turn the bike over.

12. After the fork is inside the head tube, slide the other race over the fork steering tube and down into the top cup of the head tube.

13. Screw on the adjustable cup or cone until it presses down slightly on the bearings.

14. Slide any washers, locknut, and anything else over the fork steering tube in their original order.

15. Follow the procedure in the “Threaded headsets” section under “Adjusting your headset.”

16. Insert the stem and, when it’s at the correct height, turn the bolt clockwise.

This will expand the wedge at the bottom of the stem and hold it in place.

When you adjust the height of the stem, don’t set it higher than the safety limit marking engraved into the side of the stem. It may have faded over time, so you need to look carefully to find it.