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Hi,

Anybody else had any issues with the bmc team machine slr03 2015 headset?

I've had the bike for almost a year & have had to return it to the shop three times because the headset keeps coming loose!

Last time I was getting it seen to the mechanic said this has been a problem for a few of the bmc's. I'd be keen to get in touch with someone who's had similar problems.

Regards

13 comments

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Jack Osbourne snr [715 posts] 1 year ago
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No BMC experience, but plenty of experience of seeing new bikes recurring headset issues.

Check the bung in the steerer... Carbon steerer bungs can frequently look okay but have actually slipped just enough to allow headset play.
Check position of top part of bung. If there is ANY gap between the top of the steerer and the underside of the bung's top cap then that's your problem.
The permanent solution is a longer bung which are readily available for a few quid. You can also use carbon paste, but the longer bung is my first choice. Don't be tempted to over-torque the bung to make it tighter as that can all too easily trash the fork steerer.

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turboprannet [303 posts] 1 year ago
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I have a SLR03. Jack Osbourne Snr is right, carbon bungs work loose and need maintenance. I use carbon paste and give it a regular check, it's the same on my other carbon bikes. It's no big deal really. 

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Hobo120 [9 posts] 1 year ago
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Thanks for the responses, much appreciated.

What I didn't mention previously is that I contacted bmc directly the first time it happened. they suggested that the fork shaft was cut too long by 2mm. Have you heard of this happening before?

You both make it sound pretty easy to fix & I'd be happy to do the job. It does make me wonder why the shops mechanics are making such hard work of it. I've contacted their customer service dept via email as I am fairly pissed off that despite several attempts at resolving this they have failed.

Until I hear back from them I'm reluctant to disassemble the unit incase they try to blame me for the issue.

If anyone is interested I'll post again when I get it sorted.

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andsaw [36 posts] 1 year ago
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I have 2 cannondales 1 carbon and 1 ally and both had headsets clicking and would have to keep tightening, i solved mine with  BBB Bap-03 bungs as they have knurled finish and 40mm long as the  cannondales has 20mm emery paper type finish and worked out they were moving upwards with each tightening, been quiet ever since.

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orderodonata [8 posts] 1 year ago
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turboprannet wrote:

I have a SLR03. Jack Osbourne Snr is right, carbon bungs work loose and need maintenance. I use carbon paste and give it a regular check, it's the same on my other carbon bikes. It's no big deal really. 

 

Surely the point of the bung/head cap is just to set the initial load on the headset bearings, and it's the stem that keeps everything tight? Never had a stem loosen on me.

I suppose a headset might take time to bed in if it's not fitted perfectly in the first place though?

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Jack Osbourne snr [715 posts] 1 year ago
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orderodonata wrote:
turboprannet wrote:

I have a SLR03. Jack Osbourne Snr is right, carbon bungs work loose and need maintenance. I use carbon paste and give it a regular check, it's the same on my other carbon bikes. It's no big deal really. 

 

Surely the point of the bung/head cap is just to set the initial load on the headset bearings, and it's the stem that keeps everything tight? Never had a stem loosen on me.

I suppose a headset might take time to bed in if it's not fitted perfectly in the first place though?

What happens is that tightening the top cap pulls the bung up and outwards from the steerer. If the bung doesn't have sufficient grip on the inside of the steerer this constant pull plus the vibration and forces at play while riding will move the bung.

At the same time, the other components in the headset will gradually loosen off. This happens in minute increments but over the miles eventually works its way to being noticeable.

This can occur in even the most flawlessly put together setup where a carbon steerer and bung are involved, purely because the steerer is too smooth inside and the bung can't provide enough grip to counteract the forces pulling it out. If it happens in an ally steerer with a star-fangled nut it's only going to be down to shoddy workmanship.

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Hobo120 [9 posts] 1 year ago
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What do you think of the response from bmc saying that the forks were cut too long? Anyone heard of this happening?

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Jack Osbourne snr [715 posts] 1 year ago
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Hobo120 wrote:

What do you think of the response from bmc saying that the forks were cut too long? Anyone heard of this happening?

Utter mince.

If that were the case you would simply bang on a 5mm spacer and the problem would disappear. Permanently.

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Hobo120 [9 posts] 1 year ago
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Thanks Jack. So maybe that's not the problem then as despite an extra spacer being applied it's still working itself loose. Or could some damage have been caused by it coming loose in the first place?

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Nick Forster [14 posts] 1 year ago
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It sounds like the problem is down to the bung moving in the steerer, in which case the solution is to take it apart, degrease the steerer, stem and bung, and reassemble with carbon assembly paste, the correct torques throughout and a little grease on the expander thread in the bung. Check that the bung actually works, too: does it expand when you tighten the expander bolt?

If that doesn't work then you might need to try a different design of bung - like the BBB one referred to above.

It could be that there is some damage inside the steerer - if in doubt get it checked by your LBS - but it's more likely to be a combination of grease and dirt just stopping the bung from gripping, either by getting in between the bung and the inside of the steerer or by stopping the bung from expanding as designed when the expander bolt is torqued-up.

They take some patience, and they're not maintenance-free like star-fangled nuts.

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Jack Osbourne snr [715 posts] 1 year ago
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It's the bung, mate. 100%

If the issue is recurrent, it's the bung.

Pick any combination of the advice above from myself, turbo or Nick and either have a bash it fixing it yourself or take it to a shop and tell them you want your bung sorted.

I would be tempted to find another shop than the one you've been using though. The mechanic obviously isn't too hot.

I'm guessing it was a large cycling chain? Beginning with E?

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Hobo120 [9 posts] 1 year ago
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Thanks for all the advice. I'm still waiting to hear from the shop, I'll give them one more chance at fixing it. not sure I'd get the time to dedicate to diy it unfortunately. As for the name of the shop, I'm not here to slag anyone off, just get some advice on how to get my bike back in shape.

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Jack Osbourne snr [715 posts] 1 year ago
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That's very honourable of you.

I however have no issue in calling out poor workmanship or lack of knowledge in bike trade professionals. It keeps everyone aware that you shouldn't necessarily trust what the "qualified" guy in front of you is saying.

In your case its fairly obvious that at no point have they bothered to strip the headset down to check all of its components.

While the likelihood of a catastrophic failure in this case is reasonablly small, I would expect ANY shop presented with a recurrent issue to think "hang on... I'd better look at this very carefully...something obviously isn't right"