Monday, March 18, 2013

How-To: Service your headset

The headset of your bicycle is one of those components that is frequently overlooked.  Although headsets don’t require the regular maintenance high wear items like your drivetrain do, it is still important to keep the bearings in good shape and it's very important that it is properly adjusted.

There are a few different types of headsets but fundamentally they function the same.  Today we are dealing with a very common type of headset which goes by a few different names.  I refer to these as “zero stack”, they can also be called “semi-integrated” or “internal”.

Here are the 3 main types of headset.
Integrated – often found on lower end bicycles these bearings run directly against the head tube of the frame.  Therefor the bearing races cannot be replaced.

Zero Stack – probably the most common headset on most of todays modern bicycles.  The head tube is designed to hold a cartridge bearing inside of it.  This mostly hides the bearing from sight.  The bearing is easy to replace if it gets worn out or damaged.

Conventional – Common up until about 10 years ago, conventional headsets are a self contained unit.  Often “loose ball” style bearings complete with bearing races.  This headset is pressed partially into the headtube but most of the headset remains visible.

Zero stack is really the most sensible headset option.  There are a few major advantages to this system.
-you can replace the bearing very easily, and cheaply.
-the headset is very low profile which allows you to run your stem closer to your frame.  This means handlebars can be lower in height which allows you to tailor the fit of your bike better.
-since the bearing is low profile, head tubes can be made larger which increases frame stiffness and steering response.

This How-To will address headset removal, cleaning, installation, and adjustment.  Headsets can also be a common source for creaks and squeaks so this service will reduce the likelyhood of those as well.

Tools required (left to right):
1 – rag for cleaning
2 – Allen keys
3 – all purpose grease
* - optional, makes life easier.
*4 – long zip tie
*5 – side cutters


 Step 1
A bike stand always makes life easier.  With your bike secured in the stand, remove the front wheel to take some weight off the front end.
Step 2
Loosen the stem pinch bolts.
Step 3
Remove the top cap.  At this point you must hold onto your fork or it could drop unexpectedly out of your bike and onto the ground.
Step 4
Determine whether your fork steerer tube is properly adjusted.  The deal here is that your fork steerer MUST NOT touch your top cap.  The reason for this is that the top cap adjusts the load on the headset bearing.  If the steerer tube of the fork is resting against the top cap then the headset cannot be tightened any further.

In the illustration below you can see that when you tighten the top cap it squeezes the bearing of the headset.  If your fork steerer is too long you won’t be able to tighten the headset enough.  You can adjust the length of the steerer either by adding spacers or by cutting the steerer tube shorter.
If the steerer is too short then the top pinch bolt on your stem won’t tighten the stem onto the steerer tube of the fork and you could crack your stem.  The top pinch bolt of your stem needs to clamp down onto steerer for the most secure fit.

Step 5
Begin disassembling your headset.  Start by removing your stem.

Step 6
As you are removing various bits of your headset it is a very good idea to set them aside in the order that you are taking them off the bike.  That way you know how it all goes back together.
With your spacers and headset dust shield removed now you can remove the small taper ring.  Sometimes you have to tap on the top of your fork steerer in order to knock it free.  Use either your hand or a rubber mallet.

Step 7
Now you can use that long zip tie to hold the fork in place.  That way you don’t have to remove the front brake.

Step 8
Now we are getting into the real meat ‘n potatoes of this How-To.  You can remove the top headset cartridge bearing.  You should be able to just pull  it out with your fingers.  Might have to wiggle it around a little.

Step 9
Remove the bottom bearing much like you did with the top bearing.  The bottom bearing is much more exposed to dirt and water so it is very likely that this bearing will be in worse shape than the top bearing.  It may also be a different size since many modern bikes/forks come with tapered head/steerer tubes now.
The bottom bearing sometimes comes out with the fork as well.  So you might see it on the base of the steerer tube.

Step 10
Set everything aside.  Here you can see that I have kept it all in order.

Step 11
With everything apart, now is the time to clean everything up.  Anytime you have moving parts interacting with each other you need to have very clean mating surfaces.  This reduces the risk of contamination and any number of undesirable crunchy, clicking noises when stuff does start moving or is stressed.

Step 12
Roll each bearing in your fingers and make sure they move freely.  If you want to be a superstar then some bearings can be flushed out and re-greased.  Check out “How to clean cartridge bearings” to get the jist of this process.
If the bearings are notchy or rough then chances are it is time to replace that sucker.  The good news is that they only cost about $30.  The beauty of cartridge bearings.

Step 13
Now that everything is cleaned up and functioning well you can start putting it all back together.  It is a very good idea to have a film of grease on any mating surface of a bearing.  Helps to reduce creaks big time.  You can use your all purpose grease for this job.  Take some grease and roll the bearing around in your fingers giving every surface a thorough coat.

Step 14
Re-install the bottom bearing.  Look to see if there are any tapered surfaces on the bearing.  If there are make sure they are orientated correctly.  Give them a test fit, it will be obvious which way it goes if you forgot to keep track during disassembly.
Slide the bottom bearing onto the fork steerer.

Step 15
Re-install the top bearing.  Make sure it is seated squarely in the frame.  You just push it in with your fingers.



Step 16
Install the fork back into the head tube of the bicycle.  Make sure that when you are pushing the steerer through that it doesn’t knock the top bearing out onto the ground or you’ll have to clean/grease it all over again.
Also when you install the fork make sure that all the cable and hoses for your brakes and shifters are correctly positioned.


Step 17
Make sure the fork is seated in the frame of the bicycle.  Check for any weird looking gaps at the bottom bearing.  Also double check that all the shift and brake housing and hoses are orientated correctly.


Step 18
Install all the little spacers and rings in the order you removed them.  Don’t worry if the small taper ring doesn’t push down all the way.  When you tighten everything down it will push into place.  You can grease the taper ring as well.

Step 19
Slide your stem back on and loosely install the top cap.

Adjust your headset
Step 20

Now you can begin the process of actually adjusting your headset properly.  When you know the process this is a job that takes about 60 seconds.
Remove your bike from the stand and put your front wheel back on.  Right now your stem and front wheel should move independently of each other because the stem pinch bolts are still loose.  This is important.
We learned before that when you tighten the top cap, and your stem bolts are loose, it will tighten the load on the headset.  Since we just had everything apart I suggest that you tighten the top cap to about a 6 out of 10 (10N-m approx) so that everything gets squished together nice and square.  Then loosen the top cap right off again and go from there.
You want enough load on the bearing that the bars spin freely but so the bearing doesn’t have play.  Adjust the bearing pre-load via the top cap to where you think it is a good compromise.  You can test the bearing buy snugging down one of the stem pinch bolts.  Turn the handlebars side to side through their full range of motion.  If the bearing feels rough then it is too tight.
To test if the bearing is too loose you can squeeze the front brake lever and rock the bike back and forth (front to back).  Place your hand between the bearing and the head tube of the frame to detect any knocking of the bearing.
Keep fine tuning that sucker so that there is no play in the bearing but the bars are still buttery smooth when you turn them.
 
 

Step 21
Now that the bearing preload has been properly adjusted you can make sure your stem is aligned with your front wheel.  Pretty much just eye-ball it and tighten the stem pinch bolts to secure it in place.  If later you find that it is actually crooked, or you have a crash and they turn, you can always loosen the stem pinch bolts and straighten the stem without affecting the preload on the headset bearing because you are not adjusting the top cap.

That’s it, you’re all done!  Now you can turn like a boss and your bike should run a little quieter.

3 comments:

  1. Awesome tutorial! It would be even better if I owned a bike!

    ReplyDelete
  2. Really impressed with your instructions !!!
    Thank a lot.
    Jo Smet Adelaide

    ReplyDelete