Ceramic Bearings View Article. Trade Resources. Loosen stem and remove bars and stem from steering column. Pull fork from bike. It may be necessary to use mallet and tap top of steering column driving fork downward. Once fork is driven down as little as 25mm one inch , lift fork back up and remove center cone from adjusting race. Remove fork. Note orientation of bearing retainer if any.
Squeeze sides of prongs and pull tool fully into head tube. Do not press with hand on bottom of tool, as prongs will close and pinch flesh. A clicking sound will be heard as tool engages head tube cup. Use a hammer at end of RT-1 and drive cup from head tube. Use care as cup approaches end of tube, as tool may fall to ground on last blow of the hammer. Place RT-1 with small end first through remaining cup and remove. Remove fork crown race from fork. An optional procedure to the above is to drive the race off using a punch and hammer.
In some cases this may scar the fork and crown race. Determine the acceptability of the headset press fit as described above. Adjust threaded press plate of HHP-2 until top is flush with end of hex shaft thread Remove sliding press plate and install cups onto guides. Guides are used to maintain cup alignment while pressing. Before using cup guide, insert guide into cup. Do not use cup guides if guides press on any preinstalled cup-bearing unit ex.
For headsets not fitting cup guides, simply press using threaded press plate and sliding press plate. Pressure on the outer rim of aluminum head cups may visually scar the cups.
If not using the guides, it can help to press one cup at at time. Place upper headset cup on top of head tube. Hold one cup guide onto top threaded press plate and lower assembly through top headset cup. Install second cup guide onto sliding press plate, and place lower cup onto guide.
Engage sliding press plate onto hex shaft, and push plate upward until headset cup meets head tube. Release lever. Sliding press plate lever must be engaged in one of seven hex shaft notches. Pull downward on lower press plate to test engagement. Turn handle clockwise slowly and inspect alignment of cups as cups enter head tube.
Continue and press cups fully into head tube. If threaded press plate has bottomed on threads of hex shaft, turn threaded press plate counter clockwise until it is again flush with top of threads. Re-engage sliding plate to a higher notch, and continue to press cups. If cups will not press using handles, other problems are present and should be addressed. Grease bearing retainers and bearing race cups. NOTE: Do not grease steering column. Install bearing retainers into cup shaped races.
Place fork through head tube. Install adjusting race and race centering cone onto column. Press centering cone into adjusting race to help hold fork. Install spacers and accessories as appropriate. Install stem and snug stem bolts. Check for adequate clearance from top of column to top of stem.
Add spacer under stem if necessary. Liberally apply grease to the upper cup and install the upper bearing into the upper cup. Apply a thin layer of grease on top of the upper bearing. Threadless headsets use a centering cone sometimes called a compression ring that is pressed into the bearing by the top cover to achieve bearing load. Using headset spacers, determine the correct stem height.
If the steerer tube needs to be shortened, see the instructions on cutting on page The top cap presses the stem and spacers down on the top cover to achieve bearing load. To do this, the top cap is anchored to the fork using either a star nut for use with steel, aluminum, or titanium steerer tubes or an expansion plug for use with carbon steerer tubes and a long bolt that is set in the top cap.
To install a star nut, you must use a special star nut setter. This tool consists of two sleeves: the inner sleeve has a threaded post on which the star nut is threaded, and the outer sleeve slides over the steerer tube. The inner sleeve is hit with a hammer to drive in the star nut, and the outer sleeve keeps the inner sleeve straight and has a lip to stop the star nut from being inserted too far.
If you are using an expansion plug, install the plug so that the top cap has room to be adjusted both in and out. The expansion plug will have an Allen bolt that can be tightened to expand the plug in the steerer tube and hold it in place. Home Excerpts How to install a threadless headset.
To learn more about installing a headset, read Essential Bicycle Maintenance and Repair. Incidentally, the interface between bearing and fork is called the race crown race and top race because it originally acted as the raceway, with the bearing balls in the headset rolling directly on it.
Finally, preload must be applied to the bearings to ensure everything is secured and remains in place. The general rule is that preload should be enough to prevent any rocking or movement of the steerer tube, while still allowing the fork to rotate freely.
On a threaded headset, the bearings sit in cups that are pressed into the top and bottom of the head tube. A race sits on the fork crown, completing the bearing assembly at the bottom of the head tube. The steerer tube of the fork is threaded and a threaded race is screwed into the top of the fork to snug up against the top bearing.
The top race will generally incorporate a bearing cap with seals to shield the bearings from debris and the elements. Tightening this allows you to set the preload. This assembly is then secured with a locknut, holding the fork in place. The stem — known as a quill stem — attaches separately, sliding inside the steerer tube. It is secured by tightening the top bolt, which engages an expanding wedge at its base to clamp the stem in place.
Depending on the length of the quill, you can adjust the height of the stem easily by sliding it further up or down inside the steerer and fixing it in the correct position. The adjustment of a threaded headset also requires specific spanners sized to the large dimensions of the threaded race and locknut — not something you would necessarily want to take with you on rides. Threaded headsets can sometimes have an annoying tendency to undo themselves due to a phenomenon known as precession.
Regular care and maintenance can combat this, but still, it can be an issue. Because threaded headsets comprise multiple overlapping components, they have increased weight over modern threadless designs, which are now more commonplace. As a result of this nostalgia, threaded headsets are going through a bit of a resurgence in the custom-bike market.
The threadless headset is a much simpler and arguably superior design. As with the threaded headset, bearings are fitted at the top and bottom of the head tube. A crown race sits at the bottom of the steerer tube and mates with the lower bearings. But, unlike the threaded design, the fork is not captive to the headset and is only held in place by a stem clamped to the steerer extending through the head tube.
The stem is clamped to the outside of the steerer tube, and its height can be adjusted with spacers. Star nuts are only really used with metal steerer tubes. For carbon forks with a carbon steerer , an expander also known as a bung is installed, which spreads the load across a wider area inside the steerer. The conical crown race locates the steerer with respect to the lower bearing at the base of the head tube.
The top bearing interfaces with a slotted conical compression ring. As preload is applied, the compression ring effectively gets wedged between the top bearing and the steerer tube, tightening around the steerer as preload is applied and the slot closes. This secures the steerer tube with respect to the top bearing. On high-end headsets, the compression ring is often a captive element of the headset cap that sits on top of the headset to seal it from the elements. With preload applied, the stem can be tightened, clamping things in place.
There are a few different types of threadless headset available, but they all follow the same basic assembly principle. The differences are mainly in how the bearings are fitted into the frame. It is perfectly OK though to use a top and bottom headset of different makes, models and types, as long as the fit to the frame and fork is correct. For example, when replacing a threaded front fork with a threadless one, you could keep the bottom headset, if it fits and is in good condition.
You could cut off the threaded section of a fork steerer to use the fork with a threadless headset on a frame with a short head tube, though the fork's geometry may not produce optimal handling. You can install a threadless headset on a threaded fork, if the fork steerer is tall enough and you use a quill stem. The threads should end above the headset top race.
Use two locknuts tightened against each other to hold down the threadless top race, plus spacers as needed. In most cases, you'll have to grind away the inner lip of a top nut so you can thread it down past the top of the fork to serve as the second locknut.
The Raleigh Twenty fork in the photo below already came with a second locknut for its original Nylon-sleeve-bearing top headset, and so no grinding was needed. More about this mod If the crown race is loose, sometimes you can fix it by using a hammer and centerpunch to create a series of "craters" in the side of the surface that locates the crown race.
The raised edges of the craters may be just enough to remove the slop. Or, better, you may go to a different size headset. In particular, if you are working with a J. Since ISO. You might also use "plastic steel" epoxy glue with a filler of steel particles, available at hardware stores to build up the space between a bearing race and its seat.
Be sure to clean off the excess, so steel particles don't get into the bearing. Assemble and adjust the headset before the epoxy sets, so the races will seat fully. Threadlock compound may also work.
All of the other ball bearings on a bike spend their lives rotating round and round, but headsets spend most of their time pointing straight ahead. This creates the effect commonly known as "indexed steering" where the balls sort of "snap" into place, and the fork tends to stick in the straight-forward position. The dents in the races resemble the dents created by the Brinell hardness test procedure, and as a result, this type of damage is sometimes called "Brinelling. Some folks assume that the dents in headset races also result from impact, but actually that is not commonly the case.
Instead, it has to do with lubricant breakdown. Jobst Brandt has an article on this site describing the process in detail. Ideally, a "Brinelled" headset should be replaced, but you can often cure the problem by replacing the retainer with loose balls. You use the same size balls, but can usually fit more of them into the races if you leave the retainer out. As a result, the greater number of balls, closer together, no longer all line up with the dimples in the races.
A headset race can, on the other hand, become indented due to overload in a crash. The dents then will be deeper in the part of the race that took the impact. Usually, in this case, the fork will be bent too. The indented race s and the fork need to be replaced. Adjustment is easiest if you use two wrenches. You may use large end wrenches, or special wrenches made to fit the wrench flats of the locknut and top race -- but in a pinch, you can get by with a single large adjustable wrench. There is some risk of stripping out the tab of the keyed washer or of its damaging the threads of the steerer if you use a single wrench.
Older French threaded headsets use a serrated or pinned keyed washer which mates with the upper head race. With these headsets, you must back off the locknut farther so that you can rotate the upper head race. This type of headset must be used with a special handlebar stem that clamps onto the outside of the steerer, either with one or more binder bolts , or other means.
The stem is further secured by a plastic or metal cap which is bolted to the star nut. To adjust an "Aheadset"-type headset, the stem binder must be loosened, then the bolt that runs through the cap to the star nut is tightened, usually with a 5 mm Allen wrench. This presses the stem down against the tapered bushing that fits inside the adjustable cup, and takes up the slack in the system. The stem is then aligned with the front wheel and tightened with its binder bolts.
Once the stem binder bolts have been tightened, the adjusting bolt that goes to the star nut is under no significant stress, and may even be removed. The upper collar has a gap at one point, with a binder bolt to squeeze the gap together. This upper collar may also include a cable housing stop for the front brake, if the bicycle has a rigid fork and conventional cantilever or centerpull brakes. The handlebar stem is clamped tightly to the steerer, preventing the upper collar from moving upward.
As the upper collar is compressed by the binder bolt, it squeezes the lower collar downward, taking up any slack in the headset bearings. The GeForce is the only threadless headset which doesn't use the handlebar stem as part of the adjustment.
It is commonly found on Bike Friday folding bicycles made in the mids. To adjust a GeForce headset, loosen the binder bolts in the collar and the top race; screw the collar and upper bearing race together, then back off by a fraction of a turn. Tighten the binder bolt of the collar while pressing the assembly down; turn the top race to adjust it; then tighten the binder bolt of the top race.
The collar uses a 4 mm Allen wrench, and the top race, a 2. If you ride without a front fender in wet conditions, the front tire will spray filthy, gritty water right up into the lower race.
It is the lower race that supports your weight. Most headset failures occur at the lower race. To overhaul a headset, you first have to remove the stem. It usually also makes things easier if you remove the front fender, wheel and brake, or at least disconnect the front brake cable. If you have a cyclecomputer pickup mounted on the fork, you'll also need to remove one end or the other of the computer wiring.
It helps also to turn the bike upside down once the stem has been removed -- easier with a workstand. Don't rest old upward-arched drop-bar brake cables on the floor.
Once you have the fork out of the frame, you can see what kind of bearings the headset uses. The illustrations below show the assembly order for typical headsets with different types of bearings.
A headset may or may not have contact-type seals as shown under the lower bearing of the headset at the left. An integrated IS threadless headset with cartridge bearings does not have head-tube races, but instead, the cartridges install directly into recesses in the head tube of the frame. Once you have removed the fork, you can check the condition of cartridge bearings by turning them with your fingers. They should turn smoothly, though there will usually be some drag from bearing seals.
Exact replacement is needed with cartridge bearings -- or else, replace the entire headset. After cleaning a headset that uses retainers or loose bearing balls, check the bearing races for indentations and pitting.
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