The Bicycle Headset and Its Function
Small, inconspicuous and yet enormously important: the headset sits hidden in the steerer tube of every bike, consisting of two stable layers at the top and bottom of the steerer tube. The steerer tube is located in these layers. The headset ensures that the fork sits firmly in the frame, but still allows you to handlebars. This is why the headset is also called the headset bearing or steering bearing. Due to the high load, it is a wearing part. Therefore, if the layers become stiff, you need to replace it.
However, this is anything but easy - at least when it comes to buying the right headset. This is because numerous designs and dimensions have developed over the years. In short, there are many different headsets and you need to pay attention to a few things when buying a new headset.
Threaded Headset Vs. Ahead Headset
The first basic distinction you should know when it comes to headsets is between a threaded head set and an Ahead headset. The following applies:
- Ahead headset: All modern headsets - including the road bike headset and the mountain bike headset - are Ahead headsets. This means that the bearing play is adjusted by means of a screw located at the top of the headset cover. The headset is fixed via the stem clamp. The headset is covered by the so-called Ahead cap.
- Threaded headset: Here, the headset is fixed to a thread in the steerer tube with a nut. This design used to be common, but today it is mostly found on retro bikes.
S.I.H.S. - The Types of Headset
In all likelihood, you have an Ahead headset on your bike. But there are differences here too. To help you find the right type of Ahead headset, the Standardized Headset Identification System - S.I.H.S. for short - has been in place since 2021. This system is designed to make it easier to classify headsets, with the following three main types being distinguished:
- External Cup (EC): In this traditional design, two bottom bracket cups are pressed into the steerer, in which the two headset bearings then rest. The headset is located outside the frame and the steerer becomes longer depending on the height of the two cups.
- Zero Stack (ZS): With the semi-integrated headset, two bottom bracket cups are pressed into the frame. However, apart from a narrow ring, these are completely inside the steerer. They do not change the steerer length.
- Internal Stack (IS): The integrated headset does not require any bottom bracket cups. The bearing seat is precisely preformed in the steerer and the headset bearings are located directly in the steerer. There is no protrusion whatsoever.
Bicycle Headset - What Else You Need to Look Out for When Buying
In addition to these three main groups, the dimensions of your headset are essential. In particular, the steerer tube diameter and the layers diameter are the two most important parameters here.
- Steerer tube diameter: The steerer tube of forks comes in different diameters. This dimension is crucial when looking for a headset with the right layers. In the past, all steerer tubes had one diameter (straight). 1 1/8 inch is common, but 1.5 inch is also not uncommon. Nowadays, however, there are also steerer tubes with a diameter that increases towards the fork crown (tapered). Common here are 1 1/8 to 1 1/4 inch, 1 1/8 to 1 ½ inch and 1 1/8 to 1 3/8 inch.
- Bike headset bearing diameter: If you only want to buy individual bearings, the inner and outer diameter must match: inside to the steerer tube, outside to the bearing seat.
How to Find the Right Headset at BIKE24
If you want to buy a new headset, you need to know exactly which headset you need. The dimensions of the steerer tube that the headset should accommodate are particularly important. This information will help you find the right model. You can use the filter menu on the left to conveniently pre-sort the headsets in our range, which should make your search much easier. Our customer service team will also be happy to advise you on buying a headset.