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When I wrap my fingers around my roadie's headset, I'm able to 'rotate' some parts of it freely around.

Should this be happening? If it should not be happening, what is causing this and is it dangerous? The bolt that attaches the stem to the headset near the topcap (not sure if that's the proper way to describe it) is tightened, so it won't be due to a loose bolt.

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  • Tightened. How tight? If it rotates then the most likely cause is the bolt is not tight enough. Those bolts have torque settings.
    – paparazzo
    Commented Feb 10, 2015 at 14:24
  • If you can move anything, something is probably too loose. What that is depends on what's moving and what type of headset you have. If you don't know what kind of headset you have, or what the various parts are called, take a picture, label it with what's moving, and edit it into your post.
    – jimchristie
    Commented Feb 10, 2015 at 14:59
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    Are these the spacers? A diagram would help immensely.
    – Batman
    Commented Feb 10, 2015 at 16:05
  • If he is talking about the topcap bolt, it won't have a torque setting. Commented Feb 10, 2015 at 18:51
  • Is it a sealed hub?
    – Alexander
    Commented Feb 10, 2015 at 19:57

2 Answers 2

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Most likely you are describing a spacer, but it is not clear.

headset diagram

The spacers should not spin. If they do, it's a sign that the bearings have little or no pre-load and the head set will be loose.

Couple possible causes

  1. The pinch bolts were not loose when the top cap was tightened.

  2. You are missing a spacer.
    If you want to lower the bar, you move a spacer from below to above. Someone may have removed a spacer to lower the bar without replacing it above the stem.

Internal view of head assembly

Internal view of head assembly

Note: There must be a gap between the top of the steerer tube (fork) and the top cap. If not, the cap bolt cannot pre-load the bearings and a spacer needs to be added. It can be added above the stem if desired. Alternately the steerer can be cut shorter.

How to fix:

(Should take no more than a few minutes)

  1. Back off the cap bolt a couple of turns. Loosen the pinch bolts on the stem until it can easily rotate.
  2. Tighten the top cap bolt (not too much). This sets the bearing pre-load.
  3. Tighten the pinch bolts.

If this does not work

  1. Leave the pinch bolts tight and remove the top cap.
  2. Check for a gap between the top of the stem/top spacer and the top of the steerer.
    • If there's no gap, go to your LBS and get a spacer or two (a few dollars at most).

    • If there is a gap, and the spacers below the stem are still turning, something is very wrong. Check that the threads on the bolt and star nut are not the problem.

Refer to this wikibook for instructions.

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  • By the way, what's wrong with spacers rotating even if all present?
    – Rilakkuma
    Commented Feb 10, 2015 at 18:10
  • @Rilakkuma What is right with it? Why would you even have spacers if they were not meant to bear weight? How would the top cap put tension on the bearings if the spacers are spaced?
    – paparazzo
    Commented Feb 10, 2015 at 18:28
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    @Blam: In a threadless headset the stem keeps the tension on the headset. After the stem is tightened the top bolt does not need to provide any force. As such, any spacers above the stem can spin with no ill effect. Commented Feb 10, 2015 at 19:28
  • @whatsisname Sliding in the "above the stem" is maybe a bit deceptive? Really you think the likely problem here is they loosened the pinch bolts, tightened the top cap, tightened the pinch bolts, and then loosened top cap to cause spacers above the stem to spin. OP states the the top cap bolt is tight.
    – paparazzo
    Commented Feb 10, 2015 at 19:49
  • @Blam: there is nothing in your comment to indicate you were speaking specifically about the OP's issue, whereas the comment you responded to is asking about general principles. Commented Feb 10, 2015 at 19:57
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As said - should not be rotating.

A simple check - Pull the front brake only to lock the front wheel and hold. Now rock the bike back and forth.

If there is a "click" pushing the bike forward / backward - it is likely the headset is lose.

You say the headset allen key nut is tight and compressing the headset? But how tall is the steerer tube - or put another way - how close is the top of the steerer tube to the top of the stem.

If it is very near level - you are missing a spacer - and now matter how tight the nut is - it will not provide enough compression / tightness of the headset.

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  • I think I understand your answer but I don't think OP knows what a spacer it.
    – paparazzo
    Commented Feb 10, 2015 at 16:05
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    @Blam, whatever, first step is to conduct the experiment outlined above and from there we can work out the cause.
    – Vorac
    Commented Feb 10, 2015 at 16:53

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