Headset problems / the headset thread
Discussion
Having issues with my headset.
The bike is a Norco gravel bike with around 10k miles under its belt. I've never had the headset apart until now, although I did ask my LBS to have a look at it a while back (but judging by the state of it he didn't clean much).
Basically it keeps losing its preload. First noticeable fore/aft movement develops under braking, then the preload bolt comes noriceably loose and the top cap starts rattling. I can re-set the preload and nip up the stem pinch bolts no problem but after 10-50 miles the issue returns.
I asked the LBS to take a look at it, and suggested maybe the bearings are shot, when it went in for a gear cable a few months ago. He said the headset was fine but one of the threads in the stem was crossed, so he bunged a replacement stem on FOC and sent me of. That was fine for a couple hundred miles, but the issue is now back.
Decided this evening to have it apart, find out what bearings it has and thoroughly clean / re-assemble before ordering new parts later. I thought perhaps some dirt has got in somewhere, creating a variable tolerance that changes as dirt comes and goes.
So its all clean. But the steerer tube is now proud of the stem. So can't set any preload. Cleaning / dismantling & re-assmbling seems to have created an extra 3-5mm of compression. How has this happened?
Assuming the solution here is to get hold of some spacers and pack out the stem to get the pre-load, then hopefully I can get it all set up and see how it goes.
Anything I'm doing wrong here? I can take cars apart but never really bothered faffing with bikes. I've never put enouth miles on them to require anything more than puncture repairs and cables.
The bike is a Norco gravel bike with around 10k miles under its belt. I've never had the headset apart until now, although I did ask my LBS to have a look at it a while back (but judging by the state of it he didn't clean much).
Basically it keeps losing its preload. First noticeable fore/aft movement develops under braking, then the preload bolt comes noriceably loose and the top cap starts rattling. I can re-set the preload and nip up the stem pinch bolts no problem but after 10-50 miles the issue returns.
I asked the LBS to take a look at it, and suggested maybe the bearings are shot, when it went in for a gear cable a few months ago. He said the headset was fine but one of the threads in the stem was crossed, so he bunged a replacement stem on FOC and sent me of. That was fine for a couple hundred miles, but the issue is now back.
Decided this evening to have it apart, find out what bearings it has and thoroughly clean / re-assemble before ordering new parts later. I thought perhaps some dirt has got in somewhere, creating a variable tolerance that changes as dirt comes and goes.
So its all clean. But the steerer tube is now proud of the stem. So can't set any preload. Cleaning / dismantling & re-assmbling seems to have created an extra 3-5mm of compression. How has this happened?
Assuming the solution here is to get hold of some spacers and pack out the stem to get the pre-load, then hopefully I can get it all set up and see how it goes.
Anything I'm doing wrong here? I can take cars apart but never really bothered faffing with bikes. I've never put enouth miles on them to require anything more than puncture repairs and cables.
Edited by 2gins on Tuesday 28th June 20:34
Yes, that's original and the same i.d. as the others.
The top one looks less well finished, I can see the saw marks on the faces where it's been machined from tube. I wonder if LBS bloke took a bigger one out and replaced it with that.
The fore/aft movement is coming from the steerer tube moving in the top bearing, obviously the compression ring isn't doing its job. I wonder if the top 'race' isn't seating right due to wear. That would also allow dirt past the seal.
The top one looks less well finished, I can see the saw marks on the faces where it's been machined from tube. I wonder if LBS bloke took a bigger one out and replaced it with that.
The fore/aft movement is coming from the steerer tube moving in the top bearing, obviously the compression ring isn't doing its job. I wonder if the top 'race' isn't seating right due to wear. That would also allow dirt past the seal.
I might be misunderstanding the situation here, but the way that is stacked the stem isn't clamping the steerer.
You need to remove a good deal of the spacers and drop the stem.
It would explain why things keep coming undone. But I could be totally misreading the situation, as surely the bike shop didn't put that many spacers without there being adequate steerer?!?!?
You need to remove a good deal of the spacers and drop the stem.
It would explain why things keep coming undone. But I could be totally misreading the situation, as surely the bike shop didn't put that many spacers without there being adequate steerer?!?!?
I agree. It all looks very wrong. The stem appears not to be fully engaged with the steerer, which would explain why it rapidly loosens. The top cap does not look correctly seated. I'd lose some of those spacers and replace with fewer, larger ones too.
Headset and stem assembly is very simple. Slightly worrying that your LBS failed to resolve this.
Headset and stem assembly is very simple. Slightly worrying that your LBS failed to resolve this.
Edited by ribbit on Wednesday 29th June 10:00
If what we can see there is that the steerer only comes half way up the height of the stem, your problem is you have way too many spacers underneath. Take enough out so that there’s some stem visible on top, cover that with a spacer that’s taller than the visible part, then put on the top cap.
Firstly, that looks dangerous and I'd strongly advise not riding the bike until it's fixed.
It's not entirely clear from a single photo, but it looks like you have a few issues:
1) The stem is too high and only clamping a small section of the steerer. When you're putting your weight on the handlebars, that's creating a levering force on the top of the stem that is currently only supported by air. You're running the risk of a failure of stem/steerer which could see you using your face as a brake.
2) The number of spacers is too great for the length of steerer tube.
3) It looks like the bike uses a bung for preload, but the bung isn't inserted properly (difficult to tell without appropriate pics though). My guess is that you've been cranking down on the top cap bolt to get the preload that you're missing and that this has actually just pulled the bung out.
Resolution:
1) Remove stem
2) Ensure the bung is fully inserted in to steerer and fully tightened
3) Remove several spacers from beneath the stem such that when the stem is replaced, both bolts are exerting a clamping force on the steerer tube.
4) Replace stem (don't do up bolts), ensuring that there is a couple of mm between the top of the stem and the top of the steerer
5) Replace head cap and preload
6) Tighten stem bolts to correct torque
If in any doubt, take it to a bike shop.
It's not entirely clear from a single photo, but it looks like you have a few issues:
1) The stem is too high and only clamping a small section of the steerer. When you're putting your weight on the handlebars, that's creating a levering force on the top of the stem that is currently only supported by air. You're running the risk of a failure of stem/steerer which could see you using your face as a brake.
2) The number of spacers is too great for the length of steerer tube.
3) It looks like the bike uses a bung for preload, but the bung isn't inserted properly (difficult to tell without appropriate pics though). My guess is that you've been cranking down on the top cap bolt to get the preload that you're missing and that this has actually just pulled the bung out.
Resolution:
1) Remove stem
2) Ensure the bung is fully inserted in to steerer and fully tightened
3) Remove several spacers from beneath the stem such that when the stem is replaced, both bolts are exerting a clamping force on the steerer tube.
4) Replace stem (don't do up bolts), ensuring that there is a couple of mm between the top of the stem and the top of the steerer
5) Replace head cap and preload
6) Tighten stem bolts to correct torque
If in any doubt, take it to a bike shop.
calvinhobbes said:
Firstly, that looks dangerous and I'd strongly advise not riding the bike until it's fixed.
It's not entirely clear from a single photo, but it looks like you have a few issues:
1) The stem is too high and only clamping a small section of the steerer. When you're putting your weight on the handlebars, that's creating a levering force on the top of the stem that is currently only supported by air. You're running the risk of a failure of stem/steerer which could see you using your face as a brake.
2) The number of spacers is too great for the length of steerer tube.
3) It looks like the bike uses a bung for preload, but the bung isn't inserted properly (difficult to tell without appropriate pics though). My guess is that you've been cranking down on the top cap bolt to get the preload that you're missing and that this has actually just pulled the bung out.
Resolution:
1) Remove stem
2) Ensure the bung is fully inserted in to steerer and fully tightened
3) Remove several spacers from beneath the stem such that when the stem is replaced, both bolts are exerting a clamping force on the steerer tube.
4) Replace stem (don't do up bolts), ensuring that there is a couple of mm between the top of the stem and the top of the steerer
5) Replace head cap and preload
6) Tighten stem bolts to correct torque
If in any doubt, take it to a bike shop.
What he said. It's not entirely clear from a single photo, but it looks like you have a few issues:
1) The stem is too high and only clamping a small section of the steerer. When you're putting your weight on the handlebars, that's creating a levering force on the top of the stem that is currently only supported by air. You're running the risk of a failure of stem/steerer which could see you using your face as a brake.
2) The number of spacers is too great for the length of steerer tube.
3) It looks like the bike uses a bung for preload, but the bung isn't inserted properly (difficult to tell without appropriate pics though). My guess is that you've been cranking down on the top cap bolt to get the preload that you're missing and that this has actually just pulled the bung out.
Resolution:
1) Remove stem
2) Ensure the bung is fully inserted in to steerer and fully tightened
3) Remove several spacers from beneath the stem such that when the stem is replaced, both bolts are exerting a clamping force on the steerer tube.
4) Replace stem (don't do up bolts), ensuring that there is a couple of mm between the top of the stem and the top of the steerer
5) Replace head cap and preload
6) Tighten stem bolts to correct torque
If in any doubt, take it to a bike shop.
If that is how the LBS left it, find a better one and don't ever go to the old one again. Or better still, do your own bike maintenance. No-one else will take as much care of your bike as you do.
There is a start nut or compression plug that is an interference fit on the inside of the steerer tube. This is the nut that the pre load bolt screws into. It sounds like the star nut is slipping. The solution would be to remove it and fit a new one. I was advised you need a special tool to do this.
pp
pp
Pickled Piper said:
There is a start nut or compression plug that is an interference fit on the inside of the steerer tube. This is the nut that the pre load bolt screws into. It sounds like the star nut is slipping. The solution would be to remove it and fit a new one. I was advised you need a special tool to do this.
pp
The star nut and the preload bolt is only for setting the preload initially, once you've tightened the stem bolts they'll maintain it.pp
Except in this case, where it looks like only one bolt is clamping onto the steerer tube!
Right. PH saves, thanks everyone.
Concur with the preload pulling the spreader sleeve out. Carbon fork so no star nut.
This is it now
I unwound a bit off the sleeve nut and it went straight in. Then took the two odd spacers out that LBS presumably added. I had about 5mm under the top cap, but a good few turns on the preload bolt so the stem went down a couple mm. It's all nice and secure now.
Concur with the preload pulling the spreader sleeve out. Carbon fork so no star nut.
This is it now
I unwound a bit off the sleeve nut and it went straight in. Then took the two odd spacers out that LBS presumably added. I had about 5mm under the top cap, but a good few turns on the preload bolt so the stem went down a couple mm. It's all nice and secure now.
There's about 1mm max in there. The spacers are the originals. All match and one is branded. I imagine the replacement stem fitted by lbs was slightly shorter than the factory one and he added whatever spacers he had lying around, then moved the spreader up to compensate.
Bit miffed I've gone through all this faff sorting it out tbh, won't be back there.
Happy days
Bit miffed I've gone through all this faff sorting it out tbh, won't be back there.
Happy days
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