I'm almost done assembling my new bike :)

There is still one thing in the way though... See the headset in the picture? It was installed by a professional (or, at least a LBS owner) when I bought the frame. Kinda came preinstalled.

After assembling the bike, I went back to the shop to have the headset adjusted. And somehow they couldn't get the thing set up properly. I tried too, and yeah, let's face it, that headset is probably bad or badly installed.

XLC A51AN headset

As is, the bike is pretty much unrideable since the fork would wobble every time I brake.

The frame is an Intec M1, see document page 6. It has a 1" 1/8 fork tube. The current headset is a XLC A51AN. I guess it's an external headset, but not really sure. http://www.intec-bikes.de/index.php?eID=tx_nawsecuredl&u=0&file=fileadmin/Downloads/SecureDownloads/ra-co/ALLE/Sortiment/INTEC/INTEC_Katalog_2015_EN.pdf&t=1428962756&hash=d367558de1db3f45634191e466256d126c14beca

There are enough spacers, allowing to tighten the top cap really hard, hard enough to almost lock the steering. Even then, the fork still wobbles. The fork tube is not cut straight, but I'm pretty sure the tube never touches the top cap.

So what are my options to fix that? (not involving yet another LBS)

  • What could explain why we can't adjust it? Can I fix this headset?
  • otherwise, which tools would I need to replace the headset with another? And what kind of headset do I need?

Also would I need to change the "fork race" (referring to the piece attached to the bottom of the fork tube, correct?) if I were to fit a different headset?

  • 1
    I will add the missing details. No need to be condescending. I could build the whole bike, but I don't have the tools for facing and installing the headset, that's why I relied on the lbs. And no, I can't find a proper lbs :(
    – Antoine
    Commented Apr 12, 2015 at 21:00
  • Did you even read the question? It mentions "which tools do I need", which roughy means I'm willing to get them and do the job myself. Btw I didn't see the facing job, so maybe it's properly done.
    – Antoine
    Commented Apr 12, 2015 at 21:12
  • 1
    Can't find much on this head set but I'm assuming it doesn't use sealed bearings. I'd check to ensure the bearing cages are installed correctly (or get rid of them altogether, they're not necessary). If they're in upside down your headset won't be seated properly.
    – DWGKNZ
    Commented Apr 13, 2015 at 12:06
  • 1
    The tools needed to replace the headset properly cost at least as much as your frame. Commented Apr 13, 2015 at 16:26
  • 2
    @Antoine: you may have bitten off more than you can chew with this bike build. I'd recommend going into Bicycles Chat as we may be able to help you better in there. Commented Apr 13, 2015 at 16:32

3 Answers 3


The wobbling could come from the fork. This is easy to check by putting a finger between two parts of the headset (as you can see here, around 0:35 ). If you brake and feel movement, problem is for sure on the headset.

If you do, is the headset the correct size, BOTH for the frame and for the tube? And are they in good shape? These parts have low tolerances because they have to fit the frame and the fork tube very tightly, and different manufacturers have slight different dimensions.

If you can, go to your usual shop and ask them to test with another one headset.

Good luck. And until you fix it, please don't ride that bike.

  • This is the correct answer. The headset was bad and needed to be replaced. I briefly tried to ride the bicycle was the wrong headset. The effect was surprising, just going left to right to left again randomly. Odd experience!
    – Antoine
    Commented Apr 15, 2015 at 10:25

You don't mention the stem in your question.

If you tighten the topcap bolt without loosening the stem clamp, you won't be preloading the headset; instead you'll be crushing the spacers between the step and topcap.

  • Oh man, thank you!! My bike has been doing this since new, tried many things, nothing worked until I saw this answer. No more chatter when I use my front brake!
    – Mark
    Commented Jan 21, 2020 at 20:06
  • I just broke my top cap in my brand new bike. After hours wondering what did I do wrong and not finding the answer in the internet, this answer was it !! I didn’t loose the stem bolts
    – GabrielBB
    Commented Jun 14, 2020 at 0:21

See Emyr's answer above. In a threadless headset (which is what is shown in the picture), the stem is what keeps the fork compressed into the head tube.

To make sure the stem is holding the fork in correctly, loosen the bolts that hold the stem to the steer tube of the fork. Then tighten the cap on top of the steer tube. You have to make sure the cap is pushing down on the rings around the steer tube, not the steer tube itself.

Now tighten the bolts on the stem around the steer tube.

You can test the fork is installed by holding the front brake and rocking the bike back and forth. If the fork is in there tight, you won't feel it move.

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