• Threaded
  
• Threadless
• Low Profile (Zero-Stack)
• Integrated System (IS)-angular contact without cups
• Microtech®
• Perdido®
• Columbus®-type (Integrated- angular contact)
• Campagnolo® Hiddenset(Integrated- angular contact)
• One-Point-Five Standard (oversized steering column)

.

There are also several bicycle manufacturers using proprietary headsets of unique design. Adjustment procedures will not be discussed here directly. See also related articles:

• Visit our Headset 101 page 2 to read about Working with Traditional Threaded Headsets.
• Visit our Headset 101 page 3 to read about Working with Threadless Headsets.
• Visit our Tool Use Tips page 1 to read about Reaming and Facing Tips.
• Visit our Tool Use Tips page 2 to read about Fork Crown Cutting Tips.
• Visit our Tool Use Tips page 3 to read about Fork Column Cutting Tips.
• Visit our Tool Use Tips page 4 to read about Fork Column Star Fangled Nut Tips.

The threaded headset was once the common headset design for most bicycles. The "threaded" in the name refers to the external threading at the top of the fork steering column. Bearing cups are pressed into the bike head tube. 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 threaded standards are 1 inch, 1-1/8 inch, and 1-1/4 inch headsets. The various standards are generally not interchangeable. For more on threaded headset including the various standards see Threaded Headsets.

Threadless headsets have many of the same features as Threaded Headsets. Bearing cups are pressed into the bike head tube. The bearings, which may be loose ball bearings, retainer ball bearings, or cartridge bearings, sit above and below the pressed races. 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. The threadless standards are 1-inch and 1-1/8 inch diameter steering column. For more on conventional threadless headset including the various standards see Threadless Headsets.

This type of headset system has, unfortunately, several names. Cane Creek® uses ZS or Zero Stack, while FSA® uses the Orbit Z series. 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 head tube. The head tube is a relatively large outside diameter, approximately 50mm, and cups allow the bearings to sit flush or even inside the head tube. The headset bearings sit "internally" to the top and bottom of the head tube. 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. Other types have the cartridge bearing and cup/holder as a unit. 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 head tube will vary between brands and type. If the bike was designed for a shallow cup, a deeper cup will not properly fit. This lack of consensus in depth makes reaming the inside of the head tube problematic.

The Low Profile type of headset is adjusted in a similar fashion as threadless headsets. Pressure is applied from an adjusting cap and bolt in the stem. The Low Profile headsets, even the "zero stack", do have some stack height, in spite of their name. The steering column is commonly 1-1/8 inch diameter.

Park Tool offers the 690-XL facer for some of the Low Profile head tubes. This facer is used with the 768 Pilot to machine the top and bottom surfaces of the head tube.

Below is a photograph of a Low Profile headset using a cup and bearing as one unit. These systems align bearings to the top and bottom on the head tube faces, there is no angular contact inside the head tube. Note image below with cup pressing into frame. Lip of bearing cup presses against head tube face.

   

The integrated system uses cartridge bearings that are supported by machining in a specially shaped head tube. The frame may also use pressed rings or retainers inside the head tube. A cartridge bearing slips into these "cups" or supports, and is simply lifted out for replacement. There is no contact with the head tube face. The bearing sits inside the head tube, and references the angular contact. There are different standards within this integrated-angular contact family, and these are not interchangeable. A table at the end of this article summarizes the various standards.

The "IS" system is considered the most common. The name Integrated System is not a registered trade name. The system uses the 45-degree bearing contact in the frame. The bearings for the 1-1/8 inch steering columns use a 41mm outside diameter with a 45-degree bearing contact in the frame. The bearing may be marked "36-45". The first number refers to the inside bearing contact with the headset race or centering cone. The second number refers to the frame contact.

The less common 36-degree angular contact standard uses a bearing for the 1-1/8 inch steering columns with a 41.5mm outside diameter. The bearings may be marked "36-36".

Bearing adjustment in these systems similar to the threadless headset. Pressure is applied from an adjusting cap and bolt in the stem.





The picture below shows the inside of the specially designed and machined head tube. The inside bevel acts as the bearing "cup". Cartridge bearing are used which drop directly into the head tube as a slip fit. There is no pressing involved. All integrated system headset bearings use the internal bearing support inside the frame, not the top face of the head tube, for proper alignment reference.

    
Internal shoulder "cup" for cartridge bearing of the 45-degree and 36-degree angular contact frames.

Use the Park Tool 756-S cutters for the 45-degree angular contact IS frames.

The Campagnolo® Hiddenset is a proprietary design, and is basically an integrated-angular contact type without cups. The frame must be compatible with this design for this headset to be used. The bearings cone races do not press into the frame. The frame has a specially machined head tube to accept the bearings. However, this standard is not interchangeable with the Integrated System described above. Adjustment is similar to a conventional threadless headset.

Steering columns may be either 1-inch or 1-1/8 inch in this standard. The bearings are a slip fit into the frame. The common 1-1/8 inch standard has a bearing outside diameter of nominally 41.8mm with a 45-degree bearing seat. Campagnolo® brand bearings use a caged ball bearing inside the bearing unit. The unit can be pulled apart to be cleaned and regreased. Some other brands use a non-serviceable bearing, which are simply replaced, not serviced.

    

The Perdido® headset is a type of low-profile system, but uses different tolerances. The Perdido® system uses pressed cups into the frame head tube. The bearings are fitted into the cups, and are not a simple slip fit like some of the low profile systems. The Perdido® standard requires a very specific head tube inside diameter. The outside diameter of the Perdido® pressed race is 44.5mm, and the recommended inside diameter of the head tube is 44.4mm. The low profile pressed cups use a 44mm OD. This means a bike designed for Low Profile (zero stack) is not directly compatible with the Perdido® system without first reaming. A bicycle made for the Perdido® can only use Perdido®, it cannot use the Low Profile types.

The Perdido® headset is adjusted like threadless headsets. Perdido® is a registered trade name of the Chris King® Company.

The Columbus type headset uses a cartridge bearing holding-cup that is pressed into the frame. The frame has no special seat machined inside the head tube. The frame head tube has an outside diameter of 45mm and a machined inside diameter of approximately 39.9mm. A cup of 45mm outside diameter is pressed into the frame. The cartridge bearings sit above and below the frame in these cups. The bearings are nominally 41.5mm outside diameter and are a slip-fit into the cups. The bearing seat of the cups is 36 degrees. This headset allows the "image" of an integrated system by matching the head tube diameter with the cup outside diameter. The Columbus®-type headsets are not interchangeable with other types. Cups are typically painted with the frame, which assists to hide their appearance on the bike. Adjustment is similar to threadless headsets.

Columbus® offers this system to frame builders with steel head tube inserts. These inserts are welded into the frame and are then effectively similar to the integrated system described above. The insert system is also in the 36-degree angular frame contact.

    

The various headset standards are outlined in the table below. An "interference fit" is also called a "press fit", where the head tube is smaller than the cup/bearing. The cup is pressed into the head tube with force. A "slip fit" allows the bearing to be installed and removed by hand, with no pressing required. In a slip fit, the outside diameter (OD) of the bearing is smaller than the inside diameter (ID) of the frame.