How to build a bike - Part 2: Headset

Other parts:
introduction
Headset
Bottom bracket and crankset
Derailleurs and chain
Steer and cables
Make the brakes and shifters work
Finishing up!

The frame and fork of the bike are connected by means of a headset. The headset is basicly a ball bearing which allows the fork to rotate with respect of the frame, thus steering the bike in the hopefully right direction. Although it's still up to the cyclist to steer properly, a well mounted headset will make the job a lot easier!

Installation of a headset might look a little complicated at first sight. Actually the installation of any part including bearings scares the hell out of a lot of people, including me. You need to adjust it properly: when it's too loose, there will be play between the parts and when it's too tight, the rotation is not smooth anymore. Both situations will lead to damage in the bearings.

But how hard can it actually be? Just keep turning those bolts until there's no play and rotation is smooth! If it makes you feel more confident grab yourself a beer and let's put those babies where they belong: between the frame and the fork!

Headsets come in a whole lot of different flavors. What they all have in common is that they consist of a ball bearing in some kind of housing (bearing cups) that is fitted in the frame and the fork. Wikipedia is your friend if you want to find out more about all the types, but I'll include a very short overview here:

Threaded headset
This type of headset is used in older types of frames. The bearing cups are fitted to the frame using a thread. Adjustment is done turning the locknut on top of the bearing. This type of bearing comes in loose parts and usually you'll need to put it all together yourself. I've no experience with this type, since I've had no problems with the headset on my old bike and I'm still keeping my fingers crossed it keeps that way.

Threadless headset
This type of headset using no threads. The bearing cups are pressed (clamped) into the frame. Adjustment of the headset is done by turning a nut on top of the fork.

Only two types of headsets would make this world way too easy, so different threadless headsets exist. So called integrated headsets have no outer bearings cups, but use the frame itself as the housing. My frame was suitable for semi-integrated headsets, which still have outer bearing cups, but these cups are put away inside the frame.

Basic message here is to check which type of headset your frame and fork are exactly before buying it. Note that for the semi-integrated headsets even different size standards exist, so double checking everything might safe you some frustrations...

Ok, now finally on to the assembly. Amazingly enough I managed to buy a frame, fork and headset of the same type first time right. My headset was from Acros (link), a German company. Let's walk through the different assembly steps:

1. Drive the star nut in the steerer tube
The star nut is pressed into the steerer tube and is used to connect the preload bolt which can adjust the headset. To press the star nut inside the steerer tube, some brute force is needed. Important is that this nut is lined up exactly straight with the steerer tube, otherwise the preload bolt will get crooked when it is turned. When googling around a bit how to put this little bastard straight into the tube you'll easily find some dedicated tools. I thought it was a good idea to visit some Local Bike Shops to ask if they would please use their dedicated tools to do the job for me.

I came back empty handed from this little mission as all the guys at the LBS gave me a strange look and told me they just slammed the bolt in... Since I'm not a particulary good slammer and seem to have developed an extraordinary talent for putting things out of line when they need to be in line, I decided to make a little home made tool to slam in the bolt.

First I got myself a little piece of pipeline which exactly fitted over the steering tube (which is 9/8” in diameter). Using a piece of wood which in turn would precisely fit into the tube, allowed my to hammer on this piece exactly in line with te steerer tube. In top of the piece of wood was modified a bit to allow it to fit into the steerer tube and to hit the nut where it was supposed to hit is.

Then it was time for the moment of truth and the nut was slammed in place. Remember to never place the fork on a surface while hammering it, but hold it in your hand to let your arm receive the impact instead of the fork.

The nut needs to be put inside just a couple of centimeters. Check the length of the preload bolt and make sure it can still easily 'reach' the star nut. You can see at the pictures how far I inserted mine.

2. Drive in the bearing cups
This step again needs force. The cups need to be clamped into the frame. And again they need to be in line in order not to crook any part of the bearings. Yet again special tools exist for this job, but thanks to some experience I saved myself the ride to the LBS and made my own tool.

The construction of the tool is well known and is very simple. Get yourself a long piece of thread and some nuts that go with it. You'll also need to pieces of wood and that all!

First check the housing for the cups for any dirt or damages. It needs to be clean to prevent it from damaging the bearing cups. Then grease the housing.

Now take the bearing cups. We're going to put some force on the outside of the cups to press them into the frame. Therefore you need to make sure you're going to press the cups and not the bearing balls inside. If necessary it might be better to remove the bearing balls. In my case the cups were 'extending' a bit, which made the removal of the bearing balls not necessary and gave me less chance of ruining the inside of the headset....

Put the bearing cups on the frame and use the thread, nuts and wood pieces as shown in the picture. By turning the nuts, we can slowly press the cups in place. While pressing make sure the cups go in straight, so you're not damaging the cups and frame. This process is a bit tricky (especially if you manage not to center the thread properly... I wonder why I was so stubborn to try it), but just take your time and it will work out.

When the cups are completely inside the trickiest part is over. Do not use exceptional force to get them in, since this will damage them. Just do it slowly and firmly...

3. Put it together!
Now the smashing and squeezing is over, the hardest part is done. Take the fork, grease it and put the lower bearing cup on it as shown on the picture. In my case this would go very easily, not needing any force.

Now put the fork into the frame, and put the top seal in place. Now you'll need to place the required amount of spacers and finally the stem over the steerer tube. Make sure the top of the stem is put slightly higher (about 3mm) then the top of the steerer tube. This will make sure the top cap is resting on the stem and not on the steerer tube when you turn the preload bolt.

Very important: do NOT secure the stem yet. The preload bolt will push the stem down, thereby adjusting the tightness of the bearings. When securing the stem before the bearings are tightened, you cannot push it down anymore. This will most likely increase your frustration level and will end in breaking the star nut inside the steerer tube when using all your might to tighten those stupid bearings. I'm proud to announce that I actually managed to avoid this situation!

Now put in the preload bolt and start tightning it. This will secure your fork to the frame. In my case this was the point at which I had the run from the garden inside my house, because the weather gods decided it was time for a good shower. You gotta love Holland.... Anyway, this explains a bit why my pictures suddenly change background!

Now, by turning the bolt, you're adjusting the bearings as well. When there's still play between the fork and frame, tighten the bolt more. Keep tightening, until the steering goes not smooth anymore. Now loosen a bit. Keep tweeking until you've got a smooth steering fork without play.

First:

Then:

Now you can secure your stem, since it's not required anymore to move up or down. Tighten it firmly and put a big smile on your face: you just installed a semi-integrated headset successfully. If you're feeling like it, don't hesitate to reward yourself with a nice beer or, if you feel it's your lucky day you can also decide to continue on the other parts of the bike!