Bike headset types and sizes

While a bike headset may not be the most visible part of your bike, it plays a crucial role in ensuring smooth steering and stability. Acting as the connection between the frame and the fork, it allows you to control the direction of your bike with ease. In this article, we’ll delve into the different bike headset types, examining their unique characteristics and functions. Understanding the various headset options available will help you to select the right replacement.

So, let’s dive in and uncover the fascinating world of bike headsets!

Two main bike headset types

Bicycle headsets are available in two main types: threaded and threadless.

Threaded headsets have a classic design with a threaded fork and headset, while threadless headsets feature a simpler, modern design. Understanding the differences between these two types is essential when it comes to choosing the right headset for your bike.

Threaded headset

A threaded headset is a classic bicycle headset that has been around for many years. They are recognisable by their threaded fork and headset design. Here are some key characteristics of threaded headsets:

• Threaded headsets have a lock nut at the top of the headset. This is used to tighten the bearings, making sure that there is no play in the headset.

• Threaded headsets feature a threaded steerer tube on the fork, allowing the headset to be adjusted and secured using threaded lock nuts.

• Threaded headsets typically have a quill stem that inserts into the steerer tube and is secured with a bolt.

How to measure an external cup headset

Threaded headsets come in two common sizes: 1″ and 1-1/8″.

To determine what size is on your bike, you can follow these simple steps:

• Remove the stem. 

• Remove the lock nut 

• Using a vernier caliper measure the outer diameter of the steerer tube.
  • If the measurement is approximately 1 inch (25.4mm), then it is a 1″ headset.

• If the measurement is around 1 1/8 inches (28.6mm), then it is a 1 1/8″ headset.

Parts of a threaded bike headset

Threaded bike headsets consist of the following parts:

• Threaded headsets may differ from each other however most of them will include:
• Fork crown race
• Caged bearings
• Bottom headset bearing cup
• Top headset bearing cup
• Caged bearings
• Top headset bearing race
• Locknut washer
• Locknut

Threadless headset

Threadless headsets are the most common type of headsets found in modern bikes. Unlike threaded counterparts, threadless headsets do not require threads on the fork steerer tube. Instead, they utilise spacers and a threadless stem to secure the bearings.

To identify a threadless headset, simply examine the top of the headset. If there is no lock nut present, it indicates a threadless stem configuration.

Threadless bike headset types

Threadless headsets divide into these categories:

• External
• Semi-integrated
• Integrated
• Tapered

Bike headset types: External cup bike headset

External cups headsets have cups that are pressed into the frame’s head tube, just like threaded headsets.

When it comes to maintenance, the external cups allow easy access for cleaning, inspecting, and servicing the bearings. These headsets come in two common sizes: 1″ and 1 1/8″.

How to measure an external cup headset

To determine if a bike headset is 1″ or 1 1/8″, you can follow these simple steps:

• Remove the stem: Loosen the bolts on the stem using an appropriate tool and slide it off the steerer tube.

• using a vernier caliper measure the outer diameter of the steerer tube: Use a caliper or ruler to measure the outer diameter of the exposed steerer tube.
• If the measurement is approximately 1 inch (25.4mm), then it is a 1″ headset.

• If the measurement is around 1 1/8 inches (28.6mm), then it is a 1 1/8″ headset.

Parts of an external bike headset

The external headset is made up of various parts that work together to ensure stable and smooth steering. For an external headset with caged bearings, these include:

• crown race
• bottom dust seal
• bottom caged bearings
• bottom headset cup
• top headset cup
• top caged bearings
• top headset bearing race
• compression ring
• spacer

For an external headset with sealed bearings, parts include:

• crown race
• bottom sealed bearing
• bottom headset cup
• top headset cup
• top sealed bearing
• compression ring
• dust seal

Bike headset types: Semi-integrated headset

Semi-integrated bike headsets, also called zero-stack headsets, provide a clean and streamlined appearance since the bearing cups are not visible from the outside.

Semi-integrated headsets are pressed into the bike frame’s head tube, just like external cup headsets. However, unlike external cup headsets, they don’t require cups to be pressed in from the outside. Instead, the bearing races sit directly inside the head tube, hence the “zero-stack” name.

They are designed for frames specifically built to accommodate this type of headset. The head tube of the frame needs to have the right dimensions and geometry to work with the semi-integrated headset.

To check if your headset is semi-integrated, take a look at the head tube. If you see protruding lips on the head tube, then it indicates a semi-integrated headset. 

Parts of a semi-integrated headset

A semi integrated headset with caged bearings is composed of various components:

• crown race
• bottom seal
• bottom caged bearings
• bottom semi-integrated headset cup
• top semi-integrated headset cup
• top caged bearings
• top seal
• top bearing race
• compression ring

A semi-integrated headset featuring sealed bearings consists of:

• crown race
• bottom sealed bearing
• bottom semi-integrated headset cup
• top semi-integrated headset cup
• top sealed bearing
• compression ring
• top seal

Bike headset types: Integrated bike headset

Integrated headsets offer a sleek design by incorporating sealed bearings directly into the frame’s head tube, eliminating the need for external cups.

To find out whether you have an integrated headset on your bike look for a smooth head tube without external cups, indicating an integrated headset.

Measuring integrated headset bearings

To ensure you get the right replacement for your integrated headset bearings, it’s essential to take accurate measurements. There are five important measurements to consider:

• the inner diameter. To measure the inner diameter of the bearing, use a vernier caliper and position its jaws at the widest point inside the bearing.

• Outer diameter. For the outer diameter, place the jaws at the widest point outside the bearing.

• Depth. The depth of the bearing refers to its thickness.

• internal bevel angle,
• and outer bevel angle of the headset bearings.

Integrated bike headset bearings typically have beveled edges on the inside and outside. The most common angle is 45 degrees, but some may have a 36-degree angle.

Sealed headset bearings might have different angles on the inside and outside (36 degrees/45 degrees).

To measure the inside angle of the bearing, you can use a set square or something with a 90-degree angle. Place the corner of the square into the bearing and see if the walls touch the inner edges completely. If they do, it’s a 45-degree angle.

If they don’t touch fully, it’s a 36-degree angle.

To measure the outer angle, you’ll need to find a corner with a 90-degree angle. This could be the edge of a piece of furniture or any other object. Choose a spare bearing with a 45-degree outer bevel angle. Then, put both the spare bearing and your old bearing together so the outer walls touch each other. If they fit in the corner, the outer wall has a 45-degree angle. If they don’t then then the outer bevel angle is 36 degrees.

Bike headset types: Tapered headset

A tapered headset refers to a type of bike headset where the steerer tube of the fork has a larger diameter at the bottom and gradually tapers down to a smaller diameter at the top. This design allows for increased strength, stiffness, and responsiveness, especially in the lower portion of the headset.

To determine if your bike has a tapered headset, you can visually inspect the steerer tube. Look for a noticeable taper where the diameter decreases from bottom to top.

Tapered headsets come in different sizes, typically referred to as “1.5-inch to 1-1/8-inch”. The first measurement represents the larger diameter at the bottom of the steerer tube, while the second measurement represents the smaller diameter at the top.

Mixing headsets

Mixing headset standards refers to using components from different headset systems on the same bike. Just like in this example where the semi-integrated bearing cup is fitted at the top and the external bearing cup at the bottom.

Conclusion to different bike headset types

In conclusion, it’s important to have a good grasp of the various types of bike headsets. Whether you’re a beginner or an experienced cyclist, understanding the characteristics and functions of threaded, threadless, integrated, and external cup headsets will help you make informed decisions when it comes to maintenance, upgrades, or replacements.

Knowing the sizes, parts, and measurements of each headset type ensures compatibility with your bike frame, fork, and other components. This knowledge empowers you to choose the right headset for your specific needs and make adjustments or replacements confidently.

Now that you have a comprehensive understanding of the different types of bike headsets and have identified which type is on your own bike, it may be time to consider replacing your old headset. If you’re unsure about how to proceed with this task, we have another helpful article available that provides guidance and step-by-step instructions for replacing a bike headset.

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