Which threaded headset

The bearings, which may be loose ball bearings, retainer ball bearings, or cartridge bearings, sit above and below the pressed races. The top most bearing-race has internal threading, and is held in place by a threaded locknut. The stem has no effect on the headset adjustment. Threaded headset sizes are designated by the outer diameter of the steering column.

This can seem confusing, because the head cups do not measure the named standard. The various standards are generally not interchangeable. For more on threaded headsets including the various standards see Threaded Headset Service. Threadless headsets have many of the same features as Threaded Headsets. Bearing cups are pressed into the bike headtube. The steering column has no threading.

The top race uses an internal centering sleeve on the column to maintain alignment to the bearing cup. Pressure is applied to the top race from the stem. Threadless Headsets must use a compatible stem that matches the steering column diameter. The stem binds to the outside of the column, and holds the top race in adjustment. For more on conventional threadless headset including the various standards see Threadless Headset Service.

This type of headset system has, unfortunately, several names. The low-profile, zero-stack, integrated-with-cups, semi-Integrated, or internal-headset systems use pressed frame cups that act as a holder for the bearings. The cups have a flange, or lip, and sit adjacent to the outer edge of the top and bottom of the headtube. The headtube is a relatively large outside diameter, approximately 50mm, and cups allow the bearings to sit flush or even inside the headtube. Some models use a cup that holds a cartridge bearing.

The cartridge bearing is a slip fit into the cups. The cups act as a bearing holder and do not take bearing movement or wear directly. These are simply replaced as a unit when it is worn out. Still another version of this type uses a cup and cone system with caged ball bearings, similar to the conventional threadless headsets. Additionally, the depth of insertion into the headtube will vary between brands and type. If the bike was designed for a shallow cup, a deeper cup will not properly fit.

The headset is the interface between the fork to the bike frame, holding it securely in place while allowing it to rotate to steer. While the interface requires lateral stiffness to withstand riding loads, including cornering, braking and potholes, it also needs to be rotationally free for steering. The two bearings at either end of the head tube are what make things work. Traditionally, these have been held in pressed cups, but modern bikes also see bearings fitted directly into the frame.

The fork steerer slides into these bearings, but requires fittings to be held securely. A crown race at the base of the steerer mates with the bottom bearing. The conical shape of the race is centred on the fork steerer.

This means it is self-centring on the bearing and, when preload is applied, the angled shape ensures it supports both axial and lateral loads. A top race performs the corresponding duties for the upper bearing. Almost all of the axial load experienced by the fork during riding will be carried by the lower bearing, because this is effectively sitting on top of the fork.

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. A cup removal tool is the right way to remove threaded headset cups.

You can use a flat-headed screwdriver, though. The technique requires continually moving the screwdriver to an adjacent point, giving a few light taps, then moving to the next point in succession. If you hammer away for too long in the one spot, the cup may wedge at an angle in the head tube—very difficult to move should it jam sideways. The crown race sits firmly on the fork crown at the base of the steerer.

To prise it clear, you need the right tool. This is a crown race removal tool and looks a bit different to the Park Tool crown race puller, to say the least! And 5x more expensive than the model we use—both are available on Amazon by the way. You could go tool-free on this of course, using a broad-head screwdriver or something similar to lever the race free. This method is also very clumsy.

Investing in a tool is the way to go. Or take the fork to a bike shop. Slide the tool down the steerer; the blades sit next to the crown. Tightening the bolts—alternating each side to keep them in balance—moves those wedge-shaped edges under the crown race gently lifting it away from the crown. The removal complete, we can now turn to installing the new threadless headset. Bang the cups in, drop the bearing in the top, slide the fork on with the crown race beaing, tighten.

Mostly correct except the part about banging in in the cups! You need a headset cup press tool to install the headset cups gently and evenly into the head tube.

A hammer and a block of wood is an option, but very clumsy. The risk of damage to the cups or the bike frame is high. No need for hammers at any point in the installation.

You firstly slip the top cup into the appropriate step on the tool shaft, the one that naturally catches the cup. The foot is next. You mount the cup onto the appropriate step then insert the shaft with the top cup into the head tube.

You slide the foot up towards the head tube until the cup makes contact. The objective is to lock the foot onto the notch closest to the head tube. At the right notch, slide the piece across into the notch. Tightening the Allen bolt ensures the foot will not move as you rotate the tool from the top. Since the force exerted during the installation is enough to hold the foot firmly in place, using the Allen bolt is not essential.

Adjustable type bearing systems use two opposing races which can be moved relative to one another. If the adjustment is too tight there will be too much pressure on the bearing surfaces and balls and the system will quickly wear out. This will cause a knocking in the bearing surfaces and again they will wear out prematurely. Generally, the bearings should be adjusted as loose as possible without play or knocking in the system.

The upper and lower bearing surfaces are connected by the steering column. The two bearing surfaces need to be parallel in order to operate smoothly. If the upper and lower surfaces of the head tube are not cut parallel, the bearings will tend to bind as the fork is rotated. This can lead to premature bearing wear and a less than desired adjustment.

The head tube can become deformed by welding or simply less than adequate manufacturing techniques. The base of the fork steering column should also be cut square to the fork. If it is not properly machined, the fork crown race will not sit square to the steering column and will add to the binding effect. This process is best left to professional mechanics. Threaded headsets consist of four bearing races, two sets of bearings, spacers and a locknut.

Two bearings races are called cups and are pressed into the head tube. Generally, the more massive looking head tube cup is the lower cup of the headset.

There will be one race for the fork crown. It is pressed onto the base of the steering column. The last race is threaded onto the steering column and is for bearing adjustment. This race opposes the top most head tube cup.

A set of bearing is located between the adjustable race and the head tube race. Another set of bearings is located between the fork crown race and the lower head tube race. One or more spacers are placed above the threaded race and a locknut is finally threaded on top to secure the adjusting race. Threaded headsets do not rely on the stem for the bearing security or adjustment.

A typical threaded headset and parts are seen below. NOTE: If you are not removing bars completely, use care not to kink or damage housing when hanging bars on bike. Headset bearing races are held by an interference fit into the head tube. An interference fit occurs when parts are held together by internal and external surfaces forced together.

There must be a slight diameter difference between the two pressed surfaces. Typically, the pressed headset race outside diameter should be between 0. When the cups are pressed, the head tube will flex and enlarge slightly to allow the cups to press. This tension is what keeps the cups tight in the frame. Use a caliper to measure the outside diameter of the cups.

Next, measure the inside diameter of the head tube in two places, each 90 degrees from the other. Average the two reading. If the head tube more than 0. If the race is between 0. If the race is equal to or smaller than the head tube, a different race should be used. See discussion of press fit standards below. The fork bearing race is pressed to the fork crown race seat.

The fork race is smaller than the crown race seat. It is the race that expands as it is pressed. Races are commonly made of bearing steel, which tend to be very hard and brittle, and do not expand to the same tolerances as the head tube. The crown race seat should larger then the race by 0. Much more difference may stress and crack the bearing race.