subject: Threaded bike headsets [print this page] Threaded bike headsets Threaded bike 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.
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.
3. Lift the stem out of the steering tube connected to the fork .
Remove the headset locknut by turning it in a counterclockwise direction.
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. 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. 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.
