My headset loosened during my ride today

[ANAO]

So I was just riding along on my way to work this morning when I came up to the GWB and usually, I (we) would just take the south path and ride across. But the folks are doing some touch-ups so the North side is open through the end of 2017. Which means dismount, climb up and down some 50 narrow, metal, harrowing stairs on each side of the bridge, then ride across the bridge.

Anyways, once I'm riding on the bridge, I grab some brakes to navigate those 2 sharp corners on the bridge to avoid the supports and I felt the headset loose.

I just went to tighten it now, sitting at work and the preload bolt was barely even engaged. I'm using a 1-1/8" stem with a thomson adapter on a 1" fork and the stem had slid down the adapter revealing about 2mm of adapter above the stem clamp, below the next 1" spacer. How does that happen?

[Mark McM]

Do you have pictures? There something in your description that seems contradictory: You say the stem slipped "down", but normally the headset tightens by pushing the stem downward; at the same time, you say the headset loosened, which normally means the stem moved upward. Are there spacers between the stem and the headset top race? Does the stem sit directly on top of these spacers (or directly against the headset, if there are no spacers)?

Follow up questions: When the stem clamp is loosened and the top cap bolt is tightened, does the top cap press against the stem, or the adapter?

[ANAO]

Originally Posted by Mark McM

Do you have pictures? There something in your description that seems contradictory: You say the stem slipped "down", but normally the headset tightens by pushing the stem downward; at the same time, you say the headset loosened, which normally means the stem moved upward. Are there spacers between the stem and the headset top race? Does the stem sit directly on top of these spacers (or directly against the headset, if there are no spacers)?

Follow up questions: When the stem clamp is loosened and the top cap bolt is tightened, does the top cap press against the stem, or the adapter?

I should have taken before tightening it all down just now. Here's what it looks like.

Sent from my SM-G930V using Tapatalk

[jtakeda]

Can we see the top cap area as well?

[Cicli]

That bearing cap is not all the way down.

[ANAO]

Originally Posted by jtakeda

Can we see the top cap area as well?

The spacers above the stem are 1".
The spacer below the stem is 1-1/8".

Perhaps the adapter is slipping below the lower spacer and somehow affecting it?

Sent from my SM-G930V using Tapatalk

[ANAO]

Originally Posted by Cicli

That bearing cap is not all the way down.

I know. I can't seem to find the right inner compression ring.

Do you have a line on one? This is the second one I've tried. The last one made turning the handlebars either impossible, or completely loose.

[bewheels]

Originally Posted by Cicli

That bearing cap is not all the way down.

+1

To be clear...the photo is from after you tightened it? Cause that ain’t right...

[jtakeda]

Originally Posted by ANAO

The spacers above the stem are 1".
The spacer below the stem is 1-1/8".

Perhaps the adapter is slipping below the lower spacer and somehow affecting it?

Sent from my SM-G930V using Tapatalk

My guess is your headset was preloaded (or so you thought) and as you hit the bumpy stuff the shim slid between your 1 1/8” spacer and your 1” fork.

Swap that 1 1/8” spacer with a 1”

[ANAO]

Originally Posted by jtakeda

My guess is your headset was preloaded (or so you thought) and as you hit the bumpy stuff the shim slid between your 1 1/8” spacer and your 1” fork.

Swap that 1 1/8” spacer with a 1”

OK, I'll try that.

I also need a new compression ring that will let the cap sit flush.

because when I had my old one and the cap sat flush, I couldn't turn the bars.

[thwart]

Originally Posted by ANAO

OK, I'll try that.

I also need a new compression ring that will let the cap sit flush.

because when I had my old one and the cap sat flush, I couldn't turn the bars.

Yeah... a CK headset may fix that. Methinks that has a lot to do with your issues.

Don't get me wrong, I have a 1" FSA headset on one of my bikes and it's fine, but...

[Jaybee]

Not that it solves your problem, but I had a similar compression ring issue with that same headset. I didn't have any issues with tightness or looseness, but the gap was bothersome. Never found a solution, rode it for a month or two, then swapped in a Cane Creek 40.

[ANAO]

Originally Posted by Jaybee

Not that it solves your problem, but I had a similar compression ring issue with that same headset. I didn't have any issues with tightness or looseness, but the gap was bothersome. Never found a solution, rode it for a month or two, then swapped in a Cane Creek 40.

Did the lack of total flushness give you issues other than the obvious aesthetic ones?

[Mark McM]

One possible theory:

You say that the spacer below the stem is 1 1/8". The stem shim also has a 1 1/8" OD, so the bottom spacer will actually fit around the shim. But if, when it was originally installed, the bottom spacer was offset slightly, then the bottom of the shim might have been pressing on top of the shim when you originally adjusted the headset. At some later point, under shock and vibration from riding, the bottom spacer may have shifted, so that the shim no longer pressed against it, thus causing a loss of headset preload.

Normally, when using a stem shim, the spacers above and below the stem will match the steerer diameter, and the shim won't be in the bearing preload path.

[ANAO]

Originally Posted by Mark McM

One possible theory:

You say that the spacer below the stem is 1 1/8". The stem shim also has a 1 1/8" OD, so the bottom spacer will actually fit around the shim. But if, when it was originally installed, the bottom spacer was offset slightly, then the bottom of the shim might have been pressing on top of the shim when you originally adjusted the headset. At some later point, under shock and vibration from riding, the bottom spacer may have shifted, so that the shim no longer pressed against it, thus causing a loss of headset preload.

Normally, when using a stem shim, the spacers above and below the stem will match the steerer diameter, and the shim won't be in the bearing preload path.

The question then becomes: will this happen to me every X times I ride my bike? If so, I should just swap out to a 1" spacer. The problem with that being that the deda stem has about a 37mm stack height and the thomson shim is about 42mm, leaving roughly 5mm that would be exposed between spacers. Which would be fine, I guess, except ugly.