View Full Version : My headset loosened during my ride today
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
10-18-2017, 01:05 PM
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?
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.https://uploads.tapatalk-cdn.com/20171018/3fdba147d51c2b5cf609ede49870b4a6.jpg
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jtakeda
10-18-2017, 01:14 PM
Can we see the top cap area as well?
Cicli
10-18-2017, 01:15 PM
That bearing cap is not all the way down.
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?https://uploads.tapatalk-cdn.com/20171018/15ef525825bf3a3bf9103df7f033aca6.jpg
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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
10-18-2017, 01:18 PM
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
10-18-2017, 01:18 PM
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?https://uploads.tapatalk-cdn.com/20171018/15ef525825bf3a3bf9103df7f033aca6.jpg
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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”
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
10-18-2017, 01:27 PM
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
10-18-2017, 01:30 PM
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.
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
10-18-2017, 01:31 PM
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.
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.
mktng
10-18-2017, 01:34 PM
check your start nut.
Jaybee
10-18-2017, 01:42 PM
Did the lack of total flushness give you issues other than the obvious aesthetic ones?
When I finally took it out, it was pretty gritty inside, especially for a bike that only saw dry road miles. So I assume I would have gone through bearings pretty frequently. It didn't feel gritty while it was on there though.
Mark McM
10-18-2017, 01:57 PM
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.
The spacers are stem are generally manufactured to have parallel faces, so as to provide a uniform bearing pre-load. The shim? Who knows.
How thick is the 1 1/8" spacer? If the shim is 42mm, then the combined height of the stem plus 1 1/8" spacers needs to be greater than 42 mm. That will ensure that the bearing preload passes only through the stem and spacers, and not through the shim. Perhaps add an extra 1 1/8" spacer above the stem (and make sure the shim doesn't press vertically on any spacers).
seanile
10-18-2017, 02:04 PM
check your start nut.
yea. when you tighten the top cap, you may be pulling the star nut up the steerer and not actually tightening anything
yea. when you tighten the top cap, you may be pulling the star nut up the steerer and not actually tightening anything
This is not the case.
johnniecakes
10-18-2017, 03:06 PM
Did you check to be sure that when you tighten everything up that the split in the adapter is not fully compressed? If it is them the inside of the adapter is not in full contact with the steerer tube.
When you figure what went wrong and before you finalize your assembly give both the inside and outside of the adapter a generous coat of carbon paste before you torque the stem to prevent it from happening.
Pierre
10-18-2017, 03:10 PM
Sorry if this was already covered but are you certain that your steerer tube is in fact SHORTER than the sum of spacers and stem?
If its flush or almost flush with the top, no amount of tightening is going to get the correct pre-load on the cups/spacer/stem.
Pierre
10-18-2017, 03:14 PM
The spacers are stem are generally manufactured to have parallel faces, so as to provide a uniform bearing pre-load. The shim? Who knows.
How thick is the 1 1/8" spacer? If the shim is 42mm, then the combined height of the stem plus 1 1/8" spacers needs to be greater than 42 mm. That will ensure that the bearing preload passes only through the stem and spacers, and not through the shim. Perhaps add an extra 1 1/8" spacer above the stem (and make sure the shim doesn't press vertically on any spacers).
Meh, I've got a 1" set-up on mine and my shim is completely covered by the stem. This allows me to continue to use 1" spacers above and below the stem if/where necessary. This also means I've got a 1" cap. I guess there is nothing wrong with using a 1 to 1 1/8 sleeve all the way up but you'd need to cut it correctly to make sure you cover the whole height above and below...seems like a pain in the a$$ to me.
Sorry if this was already covered but are you certain that your steerer tube is in fact SHORTER than the sum of spacers and stem?
If its flush or almost flush with the top, no amount of tightening is going to get the correct pre-load on the cups/spacer/stem.
The steerer is short enough.
Steve in SLO
10-18-2017, 04:05 PM
Thinking about the other end of the steerer, is it possible your crown race was not seated all the way, and after some ridng, it migrated downward, seated itself and left a gap in the spacers?
Thinking about the other end of the steerer, is it possible your crown race was not seated all the way, and after some ridng, it migrated downward, seated itself and left a gap in the spacers?Hmm possibly but I rode this fork a number of years ago on a different bike and never had an issue with thayt.
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mktng
10-18-2017, 06:02 PM
Get another shim.
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ultraman6970
10-18-2017, 09:19 PM
Maybe the top and the bottom contact surface of the stem is not straight and thats what is causing the problem. Put carbon fiber paste to the expander aswell.
charliedid
10-18-2017, 09:42 PM
How square is the steerer tube cut? If not square the starnut may not be seated straight and in turn everything shifts.
Also why not just buy a correct size 1" stem and forgo the shim deal?
marciero
10-19-2017, 05:36 AM
Meh, I've got a 1" set-up on mine and my shim is completely covered by the stem. This allows me to continue to use 1" spacers above and below the stem if/where necessary. This also means I've got a 1" cap. I guess there is nothing wrong with using a 1 to 1 1/8 sleeve all the way up but you'd need to cut it correctly to make sure you cover the whole height above and below...seems like a pain in the a$$ to me.
By all means it makes sense to have the shim out of the "bearing pre-load path" as MarkMcM suggests. Having shim completely covered by the stem accomplishes that. The best setup would be a 1" stem and no shim and 1" spacers. Next best I think is 1 1/8 stem covering shim and 1" spacers. I think that having 1 1/8 spacers that clear the shim is the least desirable. The shim would have to pass through only part of the lowest and highest spacer (at least the lowest) in order to have them both centered and not loaded. Plus you would have mismatch at the headset. I remember having 1" threadless stems back in the day...
Vientomas
10-19-2017, 10:27 AM
Use a steerer tube cutter to cut the shim to a lenght a wee bit shorther than the stem stack height and then file/sand the rough edges off. I've done this before and it works perfectly.
Pierre
10-20-2017, 09:49 AM
By all means it makes sense to have the shim out of the "bearing pre-load path" as MarkMcM suggests. Having shim completely covered by the stem accomplishes that. The best setup would be a 1" stem and no shim and 1" spacers. Next best I think is 1 1/8 stem covering shim and 1" spacers. I think that having 1 1/8 spacers that clear the shim is the least desirable. The shim would have to pass through only part of the lowest and highest spacer (at least the lowest) in order to have them both centered and not loaded. Plus you would have mismatch at the headset. I remember having 1" threadless stems back in the day...
Agree with this!
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