Bicycle Mechanics - Headset Loose

My headset loosens after every ride. The road I ride is rough in spots but I don't think that's the primary cause. I do have about 2" of shim rings under a 3T stem. I tighten down to the point there is resistance when I move the bars but when I return I can feel and see the play in the headset. It's not that old.

What do you mean 2" of shim rings? If it's under the stem, they're not shims - they're spacers used to adjust the stem height.

What's the diameter of your steerer tube and the stem's steerer clamp? Using a shim to reduce the diameter by one size is not uncommon. The shim is placed inside the stem's steerer clamp in between the fork's steerer tube.

To adjust your headset, the top cap is tightened down first to provide preload on the bearings until there is no more play. The stem clamp bolts are then tightened which holds the stem in place over the bearings. DO NOT GREASE THE CLAMPING SURFACE.

Parktool provides a very good tutorial: Threadless Headset Service (http://www.parktool.com/blog/repair-help/threadless-headset-service#adjust)

Excuse me. I meant spacers (which are a kind of shim). My steerer tube is 1 1/8". No need for shims inside the stem clamp. I know that the top cap of the headset is tightened down before the clamp is tightened to provide preload. So why does it loosen after a ride?

There may be several causes for this:

- The bearings do not set onto the headset cups/races squarely before applying preload.
- The spacers + stem do not stack properly before applying preload.
- The stem clamp bolts are not tight enough (or loosens).
- The stem clamp bolts may have been stripped.

Check if everything stacks squarely before applying preload. Check again for play after tightening - wiggle/jostle the handlebars to see if anything is moving. Then tighten the stem clamp bolts. Avoid overtightening - use a torque wrench if you have one. You can also use Loctite Blue or any thread-locking agent to avoid loosening bolts.

Make sure that you have enough shims (spacers) to make the top cap bottom on the spacers rather than on the steerer tube. When you take off the cap the steerer tube should be at least 3mm below the top of the spacer stack. If not add more or higher spacers until there is a sufficient gap.

Make sure that you have enough shims (spacers) to make the top cap bottom on the spacers rather than on the steerer tube. When you take off the cap the steerer tube should be at least 3mm below the top of the spacer stack. If not add more or higher spacers until there is a sufficient gap.

Yes I did that and noticed it was bottoming on the tube so I added a spacer and it tightened down properly but I went out for a 25 mile ride both yesterday and today and it's loose again. I decided to take a couple of spacers out lowering the stem and place them above the stem. It shouldn't make any difference but I have to try something.

How do your stem bolts turn? If they dont turn easily you probably arent getting enough torque to make sure the stem is secure to the column. Use anti seize to help with that and make sure they doent seize to the stem over time.

-SP

Did this just start to happen or did something change on the bike (seemingly unrelated) before the headset began to loosen.

You also seem to be making some mutually exclusive statements. You say that you were able to pre-load the head bearings (and they came loose during a ride) but then say the steering tube was bottoming out on top cap; these two conditions can not exists at the same time..

Did this just start to happen or did something change on the bike (seemingly unrelated) before the headset began to loosen.

You also seem to be making some mutually exclusive statements. You say that you were able to pre-load the head bearings (and they came loose during a ride) but then say the steering tube was bottoming out on top cap; these two conditions can not exists at the same time..

Yes there was a problem preloading when I realized the steerer tube wasn't cut enough for the spacers I was using. That was the first problem. There were dual problems in that the wheel bearings on the front were also loose so I took them apart, repacked them and readjusted them. I thought I discovered the problem when I also discovered that I needed to add a spacer. Is it possible that the star nut could slide up after the top cap is torqued down?

[snip] Is it possible that the star nut could slide up after the top cap is torqued down?

Boy, I've never seen a star-nut loosen in my 20 years of using them. I would try to use a black marker and mark where the star nut is located, then re-assemble. If it comes loose again, you can tell if the star-nut has moved. It certainly appears that your stem bolts are NOT torqued down enough. Also, once a headset has been pre-loaded, the bearings should be correctly and firmly in place.

Doesn't matter what happens with the preload bolt and star nut after you clamp the stem; they can even be removed. If it works well enough to give you preload, it's working.

Seems like it's your stem slipping up on the steerer. Is it a smooth steerer, or textured, just out of interest? I have a textured ally one and was surprised my stem slipped up a tad; thought I clamped it pretty good.

I'll prolly pull the clamp bolts and grease them before trying a bit harder.

Own a torque wrench? if you learn the torque spec for the stem clamp bolts,
often imprinted right there..

then you can use the numbers on the torque wrench scale
to bring the bolts up to spec without being under tight, your current situation,
or over-tight, and stripping out the threads cut in the Aluminum stem.


a star nut digs in harder to the inside of the metal tube, when pulled up.

If it is a carbon tube fork you should not have a star nut,
nor a 2" spacer stack under your stem..

I do own a torque wrench and am sensitive about over tightening into aluminum. As I said, the roads are rough here in Puerto Rico. They don't take care of potholes and when they do the patches sometimes are worse. I wonder if the constant banging into the headset (100psi on the tires) will push the clamp up?

the crown race does not get pushed thru the frame.. It takes pretty much
all the abuse. from the road surface.

perhaps a locking headset spacer on top of the upper race,
essentially a pinch bolt like a seat post collar ,
QBP part.. but smaller and flat on top and bottom.
but as they are not very big, so the bolt is small, not Much help .
I have another type from Mike Ahrens it is a little bigger thicker,
bigger bolt.
also a 28.6 with a pinch bolt to grip the steering tube,
but the 'Wise Cracker' has a second function.. a bottle opener . :beer:

we ordered 2 27.2 but one came out to be a 28.6,
I already have one like that,
[integrated headset is prone to letting the fork fall out so it keeps it together when playing with the spacer stack above it.]
so perhaps it would be useful ..
cervesa !

Sounds like the trick. Where do I find one?

http://www.ahrensbicycles.com/Bottle-Opener.htm



http://problemsolversbike.com/products/locking_headset_spacers

A QBP brand so any LBS with a QBP account

If your bike has an alloy or steel steerer pressed into a carbon fork, it may be that the steerer tube's press-fit or bond into the fork has separated, and the steerer is moving up out of the fork crown. I've seen this a couple of times, symptoms repetitive loosening of headset. Outcome if not sorted out, I can only presume as negative.

- Joel

http://www.ahrensbicycles.com/Bottle-Opener.htm



http://problemsolversbike.com/products/locking_headset_spacers

A QBP brand so any LBS with a QBP account

Thanks

If your bike has an alloy or steel steerer pressed into a carbon fork, it may be that the steerer tube's press-fit or bond into the fork has separated, and the steerer is moving up out of the fork crown. I've seen this a couple of times, symptoms repetitive loosening of headset. Outcome if not sorted out, I can only presume as negative.

- Joel

No, it's all steel.

I'd agree that you are not tightening the stem clamp bolts adequately. Remove the stem, degrease both the stem interior and steerer and reclamp it in place using proper torque, typically 6-8 N-m for an alloy or steel steerer. Basically you already have a "locking headset spacer". It's otherwise known as the stem clamp. Those locking spacers are primarilly used to allow removal of the bar/stem assembly for packing and shipping a bike without letting the fork fall out.