Mountain Biking

DIY Headset Tips and Tricks for Aspiring Bike Mechanics – Singletracks.com

This bike has an integrated headset, so all you can see externally is the large FSA dust cap. The bearings are seated directly against the inner head tube.

Each of the moving parts in contemporary mountain bikes uses a similar system to rotate and slide with minimal friction and maximum longevity. Learning to maintain and replace those active components can save heaps of cash and time. A few DIY mechanic skills may also provide the confidence to dig deeper into the forest with the knowledge that you can sort out most mishaps.

The headset in a modern bike works similarly to the bottom bracket in most cases, and if you understand one the other will likely follow closely behind. There are two main types of headsets used in new mountain bikes: EC or “external cup,” and IS or “integrated.” The basic difference is that the EC uses a set of metal cups that are pressed into the frame to hold the bearings, where the IS version uses the frame itself to hold the bearings by incorporating a pair of bearing seats into the frame itself. Zero stack or ZS headsets are also popular in modern frames and function the same way as an EC headset, though the cups sit further in the frame, creating less stack. Either of these options will use sealed cartridge bearings in a small variety of shapes and sizes, whereas older bikes used loose ball bearings in their headsets and bottom brackets. This helpful guide from Park Tool will help you determine which style your bike has.

The highlighted links below will lead to related headset installation videos or articles.

What’s in a headset?

This is an external cup headest. Right to left: crown race, lower bearing, lower bearing cup, upper bearing cup, upper bearing, cap or “dust seal”.

A messy pile of components fit under the headset umbrella. Beginning from the base, there’s the crown race. This is a thin ring that slides onto the fork’s steerer tube and sits against the fork crown, allowing a specific headset to interact with a fork. The lower bearing in a headset can have a different shape depending on how it’s designed, so the included crown race “pairs” these two components.

There are also reducer crown races that are designed to combine a fork with a 1″ steerer tube to a frame and headset that is designed to use a 1.5″ tapered steerer tube. The crown race takes up space where the wider steerer would be so that you can use a modern headset and frame with an older style narrow steerer. Reducer races are typically used on new bikes with steel steerer tubes where the frame can also accept the tapered steerer of a suspension fork. A Surly Karate Monkey is a common example.

A cut crown race like this one from Hope Tech makes the part quick and simple to install or remove.

Moving skyward slightly, the next element is the lower bearing. With nearly any production bike made in the last five years, this will be the larger of the two bearings, since it fits around the larger end of a tapered steerer tube. The bottom edge of it will be shaped to sit flush on the crown race, and the upper edge shape will match that of the lower bearing cup or the frame itself.

Here you can see a set of bearing cups pressed into the head tube with a second set alongside it for reference.

If your frame takes an external cup to house the bearing, this will be the next headset component in line from the floor to ceiling. The lower bearing either rests in this cup, or in an identically shaped piece of the frame.

Above all of that goodness, you have the frame’s head tube, wherein the steerer tube rotates and the bearings are seated. As you likely guessed, there’s another external cup pressed into the upper head tube, or a bearing seat in the frame, just like the lower. The upper bearing slots comfortable into that upper cup or frame seat.

Here’s another outlay of head set components in order, with bearing cups pressed and a second set alongside the steer tube for good measure. From left to right: Fork, crown race, lower/larger bearing, lower bearing cup, frame, upper bearing cup, upper bearing, preload spacer/spacers, dust cap, SFN, preload bolt and top cap.

A preload spacer slots between the upper bearing and the steerer tube to take up space and allow the headset to be tightened properly. On some headsets, this piece is integrated into the dust cover, while on others it’s a separate loose part. Some headsets may include a set of thin spacers that belong on top of the preload spacer to account for variances in frame headtube height above the upper bearing. Add as many of these as necessary so that the headset can move freely while not creating a gap between the dust cover and the frame.

Toward the tippy top, a dust cover is placed above the preload spacer(s) to protect the bearing from the elements and allow the system to be tightened properly.

This Cane Creek top cover has the preload spacer built-in. On other headsets, the cut blue ring in the center will be a separate piece, slotted between the upper bearing and the steerer tube.

Finally, the stem spacers and stem fill up the rest of the steerer tube. The star fangled nut (SFN), installed in the steerer tube, allows the top cap and preload bolt to pull the whole system tightly together. Then, the stem bolts are tightened to keep it snug. Now, on to some tips for headset installation and removal.

Installation trickery

The pile of tools one could conceivably own for headset and fork installation is heavier than the frame and fork combined. Tool companies make massive crown race setters that fit all lengths of steerer tubes, and the tool itself is about as cumbersome as the fork. All you really need is a hack saw or Dremel tool and about two minutes. Cut a slot in the crown race, just like the Hope race shown above, grease the steerer tube where the race will sit, and slide it in place. It will also be decidedly easier to remove with the slot cut out.

Another quick and inexpensive way to install a crown race is with a piece of plastic pipe like the one shown above. You’ll need a piece of pipe that fits over the 1.5″ fork steerer tube, and isn’t any wider than the crown race. Give the greased race a few good whacks with the pipe until it’s fully seated.

With the crown race snug against the fork crown, it’s time to cut the steerer tube to the proper length. It’s a good idea to put the steerer in the bike and measure it with all of the bearings, spacers, and stem installed. Measure thrice, mark it well, and then chop it up. You can use a hack saw and a blade guide like this one from Park Tool to get a fairly clean cut. With carbon steerer tubes like those on a lot of road and gravel bikes, this is the only way to go, and you may want to purchase a carbon-specific blade. For aluminum and steel tubes there’s a better way.

A pipe cutter like this one from Beta will give you a cleaner finished cut than any hacksaw could manage. Take it slowly, tightening the blade ever so slightly every couple of turns. This method takes a little longer than the hacksaw, and the factory-like result is worth it.