Adjusting Your Headset
The headset is the set of bearings that make it so the forks can turn smoothly. It is located on the frame at the top and bottom where the forks go through your frame. It is one of the most common adjustments that needs to be made to a bicycle. There are many different kinds of headsets. I'm going to talk about threadless headsets, since most modern bicycles use them. I'll show you how to identify if you've got a threadless headset.
How do I know my headset is loose? This is easy. Stand next to your bike with your hands on the grips. Lock your front brake. Rock the bicycle frontwards and backwards. If you feel a clunking, then your headset is probably loose. You can also hold the front brake with your left hand and put your fingers on the headset below the stem (right at the line above the large print word "king" on the headset pictured below) and then rock the bike forward and backward. You'll FEEL the headset being loose.
What to do when your headset is loose:
Here's what a threadless headset looks like:
You can tell a threadless headset by the cap on top of the stem.
The first step is to check to see that you've got room to tighten. To do this, you'll need to remove the cap on top of the headset. Most are a 5mm hex key. Loosen the cap and take it off. It should look something like this:
Headset cap off.
The part of the foks that goes through the frame and has the stem bolted to it is called the steer tube. When you remove the top cap of the headset, you can see the steer tube underneath. You want to make sure that there is 3-5mm of space between the top of the stem and the top edge of the steer tube. If there isn't that much space, then you need to add a headset spacer either above or below the stem. You can see that I have a headset spacer above my stem.
Looking inside the steer tube at the star washer
The top cap of the stem bolts into the star washer. That is pressed into the steer tube and if done so correctly, it won't come out for anything. You don't have to do anything with the star washer for adjusting the headset, I just thought I'd explain what one is.
This is a star washer outside of the steer tube.
Once you've checked to make sure you've got 3-5mm between the top of the steer tube and the top of the stem (or headset spacer), you can re-install the top cap. Tighten it down till it is snug. You don't need to crank it down tightly yet... Just snug it up.
The next step that you need to do is loosen the stem clamp bolts. This is done differently on various brands of stems. Some use a simple clamp like the Richey shown below:
Ritchey Stem Clamp Bolts
Other stems use more complex shim and sinch bolt setups. Each system has its benefits and disadvantages. Simple clamp bolts are lighter and clamp better, but they also give you something to whack your knee against.
Shim and sinch bolt stem. The bolt shown here pulls a wedge over the steer tube to tighten the stem.
The more complex clamp shown above works well and doesn't stick out to threaten your knee, but it is a little more complex and a tiny bit heavier.
Regardless of what kind of stem clamp you have, loosen the bolt or bolts that hold the stem to the steer. You don't have to remove the bolt, just loosen them up a bit. The stem may not move since the clamp is probably still tight around the steer tube. That is fine. You don't need the stem to move at all.
Put your hex key back in the top cap as shown below:
You'll want to then tighen this cap down. That will pull the steer tube up into the stem. Tighten it a little bit (1/4-1/2 turn). Then test the headset tightness again by locking the front brake and rocking the bike forward and backward. If you're still getting some clunking, tighten the cap another 1/4-1/2 turns. You should feel the clunking reduce with each tightening of the top cap. Continue tightening the top cap till the clunking is completely gone. Then pick up the front wheel and turn the handlebars right and left to make sure the forks turn freely in the headset. If you've tightened too much, back it off a little.
Next you need to tighten the stem clamp bolts again. If you've got more than one bolt, tighten them alternately. You should tighten them enough so the stem doesn't twist when you pull on the bars, but you shouldn't tighten them too much. Most stem manufacturers give torque specs. If you've got them, follow them.
When I've got the stem clamp bolts tight, I usually tighten the top cap of the stem 1/8-1/4 more turns in order to make sure it is snug.
Turn your bars again to make sure they turn freely. Lock the front brake and rock the bike forward and backward a few times to make sure the headset is adjusted correctly.
If you've got any questions, please drop me an e-mail at Peter's E-mail. If you have any doubt about what you're doing, please don't be afraid to take your bike to a shop. Riding with a loose or messed up headset is really dangerous. Headsets are easy to adjust, but if you don't get it all back together correctly, you can mess yourself up. Be careful and pay attention to how tight the bolts were when you started. Tighten them down similarly when you finish up. Have a buddy or mechanic check your work if you've got doubts.