What could be the cause of the shakiness in my mountain bike headset area?

Question

The headset was installed properly, the frame was faced when I built it up last year in March.

The spacers under the stem cap were always properly set up.

I also checked to make sure the front wheel is tight in the fork.

I also checked to make sure the brakes are not the source of the problem either.

Recently whenever I hold front brake and push and pull back on the bars something is rattling. OR whenever I pull back on the bars or hit a bump, I feel some shakiness in the steering area.

When I tighten the stem cap bolt so that this shakiness is taken care of, it is hard to steer the handlebars.

What could be wrong? Is the star fangled worn?

What else could be the problem?

An ovalized headtube?

Answer 1

Have you tried tightening the stem cap bolt before the two bolts on the side of the stem? Ive had the same problem and i solved it by doing that first. Does you bike have dual crown suspension?

Answer 2

Take it apart and check the bearings.

Answer 3

The top bolt WILL NOT tighten your headset.  Its only purpose is to preload the headset bearings to take out the slop, but if the stem bolts on your steerer tube are not loose then NO amount of tightening on the top cap bolt will do anything for you.

If this is too confusing, take it to a bike shop or visit Park Tool's web site and LEARN before you s***w something up.

Answer 4

If your headset was installed properly the headtude would have been reamed to avoid any possibility with ovalizing. The star fangled nut is a press fit so it wouldn't have any play in it.

You didn't mention if the bike had front suspension, and if it did what the brand is. Some sus forks have interchangable steerers and it is rare but possible for them to come loose. There could be wear in the stanchion bushings or in a variety of other places- especially if the fork has not been maintained. There could be a crack in the crown or in a stanchion or a dropout. If you have discs there could be a crack in the disc mount.

If it is a rigid fork and made of carbon fiber with a metal steerer STOP RIDING THE BIKE! The fork is about to fail. This is more common than I care to think about when it comes to cheaper CF versions but can happen with any CF/metal fork.

My primary suspect, however, would be the bearings. Tear it apart and make sure the bearings and races are in good shape. If you have a zero stack or external headset a race may be cracked... this usually is not easy to see.

Whatever the culprit, I would really recommend that you not ride the bike until the source is found.

Answer 5

Shakiness in the headset while braking can also be caused by a couple of things.  In general, even well adjusted brakes never grip perfectly.  They tend to grip then slip.  This pulsing isn't usually felt if your headset is in good condition and is properly adjusted.  When something is wrong, though, you'll feel it.

Hopefully, you already realize this, but the way you asked your question leads me to beleive otherwise.  In any case, tightening the cap bolt isn't going to fix anything.  The cap bolt is only there to allow you to properly adjust the headset.  The cap bolt should only be tight enough to ensure there is no play in the headset.  You do not want to tighten it to the point the handlebars become difficult to turn.  

The bolts that affix the stem to the steering tube provide all the holding power.  Thus, once the bolts on the stem are properly tightened up you can actually remove the cap bolt.  Its job, along with that of the star fangled nut, are done.  If you do not properly tighten the stem bolts, the cap bolt and star fangled nut don't provide enough holding power to keep everything together.

The correct proceedure for tightening your headset is:

1. Loosen the stem bolts

2. Gently tighten the cap bolt

3. Check for play in the headset

4. Repeat steps 2 and 3, if necessary

5. Tighten the stem bolts

On a mountain bike, the best way to check for play in the headset is to put the bike on a rack.  Then, holding onto the fork' s upper arm attempt to rock the steering tube in the headset.  Turn the fork in both directions as you rock it.  There should be no untoward movement in the headset.  If there is movement in the headset you need to give the cap bolt a slight turn.  There may be play in the suspension fork, so don't try rocking the bike from the fork's lower arm.

You should read about servicing your headset on the Park Tool Website:

http://parktool.com/repair/readhowto.asp...

There is also a possibility you have bad headset bearings.  Sealed bearings, in particular, wear out and get sloppy over time.  Sounds like it is time to pull the entire headset apart and see what's going on.

If the shakiness persists after you've got your headset if good working order, the problem could be in your fork.

Hope this helps.

Answer 6

make sure that the top bolt and the side bolts are tight.

when you check these. grap the spacers, rock the bike back and forth and twist the spacers at the same time. if the spacers move then its not tight enough.

the bearing could also be cracked, which will mean a new headset.

go to your local bike shop that you trust and get them to have a look at it if your not sure.

you dont want to crack anything by overtightening anything and you dont want to strip any bolts either.