Movement in the headset - after every ride (SOLVED - PAGE 2 UPDATE)

philthy3 wrote:

Still doesn't make sense. The top cap merely preloads on top of the stem. If the stem is tightened correctly, the steerer still shouldn't come loose even if the top cap is then removed as the stem is holding everything in place.

If there is no preload on the stem from the topcap it can travel, imagine it this way, you clamp something to a metal bar, but realise It needs to be a smidge further down. You can either slacken the bolts off and move it, or just whack it a few times an it'll move basically the same principle here, the stem is being struck from below by the spacers or headset when ridden forcing it up. As the bung is not tensioned it can move, tension the bung you stop that movement.
The bung is simply preventing the stem from travelling beyond a certain point.

No offence mate, but I'd drop your bike in at an LBS as soon as possible. Let them give it a safety check. If you didn't grasp the concept of an 'expander' bung, it makes me wonder what else you may have missed.

sungod wrote:

Pilot Pete wrote:

Do they do a smug smilie? apologies gratefully accepted from all the nay sayers who insisted it must be the stem slipping.

PP

p.s. that was a joke, don't get offended anyone. Glad to hear you got it sorted secteur.

nope, because the top-cap is immaterial

if the headset unloads, the stem is slipping, otherwise the headset would stay loaded

relying on the top cap to hold it down is bodging it

btw i'm not offended nor apologetic, just concerned that the op thinks relying on the top cap to hold a safety critical jcomponent in place is a solution

You still don't get it do you sungod? :roll:

The top cap is only immaterial if it sets the preload correctly, then the stem is tightened. If the bung offers some resistance, but not enough, the preload would feel like it is being set, especially if the top cap bolt became tight when it bottomed out on the bung, but in fact not enough preload had been set.

The stem would tighten perfectly to the correct torque and hold the steerer firmly as designed, however once the bike was ridden the lack of preload would become evident with play appearing.

The top cap is only immaterial if the preload is set, the stem tightened and everything is correct. Then, and only then you could remove the top cap and bin it if you wanted and everything would remain just right. Unfortunately for you the preload in the OPs case was never set correctly as the expander bung was not tightened sufficiently, thus the preload was never set. So can you now stop banging on about immaterial top caps and accept that you were wrong? The stem was NEVER slipping, despite you claiming it must be. Nobody has ever suggested that the top cap should be relied on to hold anything, so nothing was being bodged and nobody was suggesting that it should be. The OP has been frank enough to admit his mistake, which he realised after correct advice from a few on this thread, despite some vocal incorrect advice from others...

PP

You what'? A carbon steerer will compress and allow movement of a tightened stem? Only if you crack it by by tightening/ over tightening without the expander bung. The expander bung is there primarily to give the top cap something to tighten against and (to a lesser extent) to give the stem something to tighten against without over stressing the carbon steerer and causing it to crack. Having said that, take a piece of cut carbon steerer, put a stem on it and torque up. There will be no movement. Keep tightening the stem and you will get to a fair old torque before it cracks. It will not compress and allow movement even at normal torque.

What has been mentioned as superfluous is the top cap after the preload has been set. Nobody has suggested removing the expander bung after tightening the stem...

And as for an alloy steerer, how does a star nut prevent this 'compression'? (It doesn't as it doesn't need to with an alloy steerer as it will not compress under normal torque).

In the OPs case the expander bung was still in there and the stem tightened against it, it is just that the bung had not been tightened sufficiently in the steerer before the top cap was tightened, thus the preload was not set. The stem was holding perfectly, just not far enough down the steerer due to the lack of preload.

Can we please put this one to bed now?

PP

sungod wrote:

Pilot Pete wrote:

Do they do a smug smilie? apologies gratefully accepted from all the nay sayers who insisted it must be the stem slipping.

PP

p.s. that was a joke, don't get offended anyone. Glad to hear you got it sorted secteur.

nope, because the top-cap is immaterial

if the headset unloads, the stem is slipping, otherwise the headset would stay loaded

relying on the top cap to hold it down is bodging it

btw i'm not offended nor apologetic, just concerned that the op thinks relying on the top cap to hold a safety critical component in place is a solution

You are 100% correct Sungod. Some of the confusion here is caused by the topic title " Movement in the headset- after every ride" . It should read "... before and after every ride". The slipping bung will prevent the bearings being correctly preloaded so there will be play before every ride.Assuming the components are correctly assembled, once the stem clamps the steerer nothing can change.

Guys - I don't want to labour the point - but the only cause here is 'user error'.

darkhairedlord wrote:

Imposter wrote:

Guys - I don't want to labour the point - but the only cause here is 'user error'.

compounded by poor advise.

Maybe. But without user error, there would have been no thread.

Semantik wrote:

lesfirth wrote:

sungod wrote:

Pilot Pete wrote:

Do they do a smug smilie? apologies gratefully accepted from all the nay sayers who insisted it must be the stem slipping.

PP

p.s. that was a joke, don't get offended anyone. Glad to hear you got it sorted secteur.

nope, because the top-cap is immaterial

if the headset unloads, the stem is slipping, otherwise the headset would stay loaded

relying on the top cap to hold it down is bodging it

btw i'm not offended nor apologetic, just concerned that the op thinks relying on the top cap to hold a safety critical component in place is a solution

You are 100% correct Sungod. Some of the confusion here is caused by the topic title " Movement in the headset- after every ride" . It should read "... before and after every ride". The slipping bung will prevent the bearings being correctly preloaded so there will be play before every ride.Assuming the components are correctly assembled, once the stem clamps the steerer nothing can change.

Contradiction there. Not sure you are reading Sungod correctly- he is saying the cause is a slipping stem.
But you then refer to a slipping bung, which is actually the fault that PilotPete was (I believe correctly) identifying.

FWIW my own (now defunct) earlier suggestion to 'buy a new headset' was made before the OP revealed this was a Cannondale, which from personal experience I know would/should have quality bearings and adjustment is always easy and reliable once you know how. Not always the case with the cheap, usually unbranded headsets you can get.

I have no desire to pursue this but to someone who understands what is happening here there is no contradiction.

This cannot end until someone has won.

Bondurant wrote:

This cannot end until someone has won.

Well it certainly isn't sungod or lesfirth! :roll:

slipping, a, is, bollox, stem, of, load

Re-arrange the above to make a sentence.

And just for those who can't grasp what happened - user didn't tighten the bung in the steerer sufficiently. He then tightened the top cap, which instead of preloading the headset bearings, just took up a bit of slack before causing the bung to be pulled up the steerer towards the top cap.

Stem bolts then torqued up, which clamped the steerer PERFECTLY as designed. Unfortunately the preload had not been set and thus a little play in the bearings was evident. User noticed this after a ride.

The stem NEVER slipped anywhere. It never 'WALKED' itself up the steerer due to compressing the carbon fibre steerer :roll: It wasn't a stripped thread in a stem bolt, nor a crack in the stem, nor a damaged steerer allowing the stem to move against the steerer. The stem was held perfectly in the position it was clamped. Trouble is the stem was not clamped up low enough down the steerer (which is what setting the preload achieves). Simple as.

So, sure it was user error in not tightening the steerer bung in the steerer correctly in the first place. BUT, the OP came on here for help as he couldn't work out the issue causing the play in the bearings.

So sure Imposter, if he hadn't made the error the thread wouldn't exist, but so what? Isn't that what the Workshop forum is for - finding out how to do jobs which you don't know how to do or to get you out of a pickle (which you may have caused yourself!)

The OP has been man enough to hold his hands up and admit he was at fault, but has waded through the guff on this thread and found the solution, so he is happy. We all learn somewhere and I am happy to put my hand up saying that I have made mistakes and learnt from them as I am sure the OP has here. That's what makes an expert - someone who learns from their mistakes and eventually becomes extremely competent.

PP

lesfirth wrote:

I know I said I was not going to pursue this but my understanding of the OPs original problem was play in the headset CHANGING during a ride. The only way this can happen is for the stem to move on the steerer,however unlikely that might be . It is now clear that he was unable to set the preload because his bung was slipping, so he must have had a problem before his ride as well as after i.e.no change. Hence we have had people trying to find causes of a problem that never existed.

You are still wrong. Stop stating 'the only way is for the stem to move'. What if the bearings were failing? What if the bearings weren't seated correctly, ie not pressed home fully? What if the crown race failed or wasn't seated correctly? There are a number of ways other than the stem slipping that could cause the play to appear after a ride. Stating that something 'must be' so just because you can't see the other possibilities doesn't help anyone.

The OP never stated that the play in the headset was CHANGING during a ride. You assumed this (or more likely are trying to use this as an excuse now you have been proved wrong). He said after a ride he noticed play. It was pretty obvious that unless something was failing the most likely cause was the preload not being set correctly in the first place, not the stem moving, especially as the problem kept recurring. If you had clarified if he meant 'changing' with a simple question you could have avoided giving incorrect chapter and verse and then (and now) continuing to incorrectly state that the stem moving MUST be the only possible cause... :roll:

PP

Pilot Pete wrote:

lesfirth wrote:

I know I said I was not going to pursue this but my understanding of the OPs original problem was play in the headset CHANGING during a ride. The only way this can happen is for the stem to move on the steerer,however unlikely that might be . It is now clear that he was unable to set the preload because his bung was slipping, so he must have had a problem before his ride as well as after i.e.no change. Hence we have had people trying to find causes of a problem that never existed.

You are still wrong. Stop stating 'the only way is for the stem to move'. What if the bearings were failing? What if the bearings weren't seated correctly, ie not pressed home fully? What if the crown race failed or wasn't seated correctly? There are a number of ways other than the stem slipping that could cause the play to appear after a ride. Stating that something 'must be' so just because you can't see the other possibilities doesn't help anyone.

The OP never stated that the play in the headset was CHANGING during a ride. You assumed this (or more likely are trying to use this as an excuse now you have been proved wrong). He said after a ride he noticed play. It was pretty obvious that unless something was failing the most likely cause was the preload not being set correctly in the first place, not the stem moving, especially as the problem kept recurring. If you had clarified if he meant 'changing' with a simple question you could have avoided giving incorrect chapter and verse and then (and now) continuing to incorrectly state that the stem moving MUST be the only possible cause... :roll:

PP

To be fair, he did say this:

Secteur wrote:

Imposter wrote:

Sounds like the top cap is not tightening down properly - ie it may be tightening on the top of the steerer, rather than the stem itself. Add another spacer over the stem.

Ok, will certainly check that, but the initial tighten and first hour or so of the ride it's "tight & tidy", with just the right amount of bearing pre-load. It seems to loosen after that, but never gets to rattling - just that very slight knocking under front breaking; felt rather than heard.

Keeping on arguing over this is daft. The guy has sorted it from looking into it with some of the suggestions helping him to understand how it works, job done. Anyone who knows what they are doing with bike builds certainly won't be bothered to keep arguing, but I suppose some people just need the attention of being acknowledged they are right for some reason, bless.