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...carbon steerer. What should I do?
On-one Fatty Carbon fork BTW.
It looks like I could cut off the top part of the steerer if I needed to. I have enough length, so to speak.
Whatever you do, do not breath in 😜
Leave it alone?
Sexy Fiery Newt? Give it a back rub and see what happens.
Nothing at all. The 'damage' was done installing it, any attempts to remove will likely worsen the situation. It'll likely be vastly overbuilt, so I'd not concern yourself.
Send the forks back to the cowboy you bought them from.
Bolt your stem to it 😀
i had the same thing on my OO fatty forks, just tapped it gently a little further down. i have not died or exploded into flames. ymmv
The forks came fitted to a second-hand bike. I bought it months ago, and have been riding it frequently. The stem does not appear to have been fitted far enough down the steerer tube and there is a little bit of damage to the top of the steerer. I am going to trim the top of the tube to remove the damaged few mm, then leave the rest. The wall is pretty thick.
If you can reach it with a drill, drill out the central threaded section( it's a soft alloy i think) 10 mm bit .The sfn should collapse into pieces with out much effort.
Like I said Trouty, keep them fibres of plastic away from your face 🤪
For once, I'd be concerned...carbon forks aren't meant to have SFNs in them for a reason...
if I can, trim the steerer to below where the tube was fitted and hope no cracks have spread down past.
What kind off idiot fits a SFN to a carbon steerer?
SFN?
Star flanged nut
Fangled, not flanged.
I have removed it and trimmed off the top 5mm of the steerer. The stem had been badly fitted and the steerer did not reach high enough in the stem. The stem, a Truvativ, has a large oval cutout of the section that makes contact with the steerer, and the edge of this had damaged the top edge of the steerer.
I have ordered the on-one bung kit for these forks and it should arrive tomorrow.
What the **** is a fangled nut?
See, a nut with two flanges. Not a single fangle in sight.
No flanges in sight either.
Fandangled fantastico news about your new budget bung assuming you bought it from OO.
i had the same thing on my OO fatty forks, just tapped it gently a little further down
What ever you do, dont do this id have thought! The higher up it is in the steerer the better surely?
Some carbon forks do use SFN’s, Cannondale definitely used them on their carbon forks
Its not right, but surely an SFN in a carbon steerer as long as its not completely FUBAR isn't the end of the world, the structure means cracks should propagate less so the scoring should be less if an issue.
I thought the reason for not using an sfn was mostly that they wouldn't fit properly in the thick walls of carbon steerers?
Still not entirely sre why you felt the need to remove it or indeed to trim your steerer. The damage was done installing it. Removing it does not improve the situation and very likely makes it work doing further damage. If indeed damage was significant in the first place. Years ago I had the privilege of going around the Mclaren F1 factory and saw the state of the tubs of the cars being used that season. Cut and shut does not come even close. It change my attitude to he stuff.
Also, many folk don’t realise that the sfn or their bung equivalents should not be loaded once the bike is built up. They are merely there to draw the parts together in tension before the stem bolts clamp everything together permanently. Once done you can remove the top cap and bolt (and the sfn for that matter) with no ill effect.
Then cutting down a steerer because the original setup had too little steerer interacting with the stem.....A correct setup with a carbon steerer would be a max of 30mm of spacers the the stem with 5mm of steerer poking out the top and another spacer before the cap. I’d have had the slightly marked bit above the stem and minimized the change to the bike setup.
Thanks. I didn't know about the max 30mm requirement. It had 30mm before, so will be down to 20mm underneath, and a 5mm spacer above, which wasn't there before, and I have also learned is a good idea.
I was unaware of the no SFN in a carbon fork rule. How do they hold together without one & how do you preload the headset?
I was unaware of the no SFN in a carbon fork rule. How do they hold together without one & how do you preload the headset?
Some use something a bit like hopes head doctor where doing the bolt up expands a bung in the steerer.
Its just the sharp edges of the sfn your trying to avoid.
Does the bung not also provide some internal support to the steerer to minimise the risk of the stem crushing it?
I would imagine that tightening a stem on a steerer occupied by a SFN that is already cutting in to the surface is going to potentially generate more stress at the sharp contact between the SFN and the steerer.
Bung inserted, prelubed with carbon paste, and torque to 8nm. 25mm of spacers, followed by carbon pasted stem, another 5mm spacer then the topcap. Stem tightened to 6nm. No-one dead yet. I might brave a test ride later...
I would imagine that tightening a stem on a steerer occupied by a SFN that is already cutting in to the surface is going to potentially generate more stress at the sharp contact between the SFN and the steerer.
Yup.
I am sure most carbon will be fine with a SFN but why take the risk? As above, carbon steerers normally have a smaller ID so you really have to whack the SFN in there to make fit.
When using lock on grips on carbon bars I always make sure I have expanding style bar end plugs and still only just nip up the clamps, it helps having reinforcement in there if the end of the bar takes a knock and the beer bottle cap ones are good as the bottle cap deforms.
<div class="bbp-reply-author">crazybaboon
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<div class="bbp-reply-content">Some carbon forks do use SFN’s, Cannondale definitely used them on their carbon forks
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Really? My SuperX came with a bung and note saying never use a SFN on carbon steerers. Much like cynic-al, I ignore most guff but this is a bit of guff I wouldn't ignore.
Does the bung not also provide some internal support to the steerer to minimise the risk of the stem crushing it?
I seem to recall my Tripster forks said that the bung must line up with where the stem clamps. Or maybe the bung instructions did. Pretty much makes sense to do that.
A piccy
Funnily enough I bought a set of OO carbon forks 2nd hand. Same thing except the SFN had been rammed far down the steerer and a expander bung fitted. I never would have know but for getting inquisitive about how deep the steerer was with a torch.
I've not died yet. Although i can't be 100% sure of that.