A Guide to
In some ways, picking the right MTB headset can be rather demanding. Compared to road bikes, there are many more mountain bike headset standards out there. The headset needs to match both the head tube of your bike and also the steerer of your fork.
As far as steerer standards go, there are three main ones. Straight 1.125”, also known as 1 1/8th, is simply a steerer tube with an unchanging diameter. It’s common on older and cheaper bikes. There’s now the more modern 1.5” taper, which moves from a standard 1.125” steerer tube where the stem clamps to a wider, 1.5” diameter at the fork crown. It’s much stiffer and also lighter. Finally there’s full 1.5”, which uses an untapered steerer. It’s less common nowadays apart from on Cannondale frames.
Head tube standards vary hugely. The 1.125” standard is still common, and it uses cups which press into the head tube. The bearings then sit in these cups and can either use balls sat in a retaining cage, needing regular maintenance or sealed cartridge bearings, which are fit and forget.
On some designs, the headset bearings sit directly onto the frame or into non-removable pressed-in races. They can be known as ‘internal’ headsets as they sit inside the frame, but are also commonly referred to as ‘Campy’ headsets. This name comes from the fact that Campagnolo originally created them. They also sell headsets to fit, such as the Campagnolo Record Hidden Headset 11/8. It can be either straight 1.125” or 1.5” taper, so it’s important to get the correct upper and lower bearings, though this is easily found by looking at the steerer.
Head tube standards are plentiful, but by measuring the internal diameter of the head tube, it’s easy to tell which your frame uses and buy accordingly. Make sure you measure both the top and the bottom width, as they are different on tapered designs.
An interesting new standard is the 44mm external standard, which uses a straight 44mm internal diameter head tube. This allows you to run straight 1.125” forks with internal cups, a tapered steerer fork with a internal upper and external lower cup and a full 1.5” steerer with two external cups.
Remember that while it’s possible to run a 1.125” fork within a frame that has a tapered or 1.5” head tube with reducer races such as the Norco Reducer Crown Race, the opposite won’t work.
Headsets that allow you to change the steerer angle (‘head angle’) of your bike are also more common, allowing you to tweak frame geometry from standard for improved high speed handling. They’re available to fit a wide variety of head tube and steerer standards. The Cane Creek AngleSet ZS44/ZS56 Headset Kit is a highly popular choice.