Bicycle Repair Guide

How To Adjust a Threadless Headset

Learn how to check the adjustment of a threadless (Aheadset) and align the handlebars.


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In today’s tutorial, we’ll learn how to adjust a threadless headset, otherwise known as an ‘Aheadset. For this job, you’ll need either a 5mm or a 6mm allen key, depending on your stem.

To loosen the stem, simply turn the allen key on top counter-clockwise a few turns. Don’t remove it completely. Then loosen the two bolts on the side. Now your stem should turn freely.

To check if the headset is tight, lift the front of the bike off the ground. The handlebar should rotate freely and fall to one side or the other. If it doesn’t, you’ll have to loosen the top bolt a little bit and try it again.

To check for play, hold the front brake, place one hand on your headset, and rock the bike forward and backward. If the headset is loose you’ll feel it, and you’ll have to tighten the top bolt a little bit.

Once the adjustment is set, check the alignment. I find it easiest to line up the stem with the front wheel while you’re sitting on the bike. Once the handlebar is straight, tighten the two stem bolts and check the adjustment again just to be sure.

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9 Responses to “How To Adjust a Threadless Headset”

  1. Daniel on November 14th, 2008 12:09 pm

    Excelent tutorial!
    It was so helpful. Thanks Alex.

    Btw, I have a question. I would like to adjust handlebar height by removing one of those spacers. Can I do this and if so what I’m supposed to do with the removed one? Put it back on the top of the stem before tightening the top cap or just set it aside?

  2. Alex on November 14th, 2008 4:32 pm

    Yes, you should be able to remove a spacer, but you’ll have to put it on top of the stem (but under the top cap) to keep things together. If you can’t place the spacer on top for some reason you’d have to cut the steerer tube of the fork itself.

  3. Jocelyn on December 4th, 2008 10:04 am

    You only show how to adjust a Threadless Headset in this tutorial but what I’d like to know is this:

    Do I need to overhaul such a Headset on a regular basis? Just like you show in your other tutorial “How To Overhaul a Threaded Headset”…

    Thanks for all your tutorial… It’s helping me out a great deal…

    Status of this Request

  4. Alex on December 4th, 2008 12:22 pm

    I can do a threadless overhaul tutorial for sure. I actually was going to do it with this bike (which I borrowed), but when I pulled apart the headset it had sealed bearings, so I made the best of it and made the adjustment video. I’ve got another bike with a loose-bearing threadless headset now, so I’ll be making that one soon!

  5. rob on December 4th, 2008 8:02 pm

    Great site, I have wrecked spacers before when fiddling about here. Any chance of a tutorial on adding spacers?

  6. Alex on December 18th, 2008 1:29 pm

    Hi Rob,

    I’ll add your request to the list!

  7. Jason on January 23rd, 2009 8:46 pm

    Great info — Thanks!! I was getting ready to take my bike to a shop to fix the play in the headset but your video helped me do it myself.

  8. Michie on February 2nd, 2009 7:12 pm

    I work for a local bicycle shop. I work on the sales floor, so I am responsible for fitting customers on their bikes, which requires me to do a lot of handlebar stem swapping. I was told by the mechanics to always loosen the two pinch bolts on the stems before loosening the top bolt. They said to always do it in that order, and then to tighten, do it the opposite. Does it really make a difference, or even matter?

  9. Alex on February 3rd, 2009 2:04 pm

    I don’t think it makes a difference. It all depends on what you are repairing. I’m interested in hearing their reasoning… did they say why?

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How To Adjust a Threadless Headset
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