I have some carbon road forks that I put a star nut in... I understand that this is not the done thing and I should have used a compression thingy... Various forums seem to think my death will be imminent, but has anybody had a problem with this in the real world?
Personally i consider the so called "danger" to be overplayed, i've seen carbon forks break at the dropouts or the leg but never an upper steerer failure.
I wouldn't imagine it would just snap. The stem clamping over the outside would counter act the expansion force from the star nut. I wouldn't recommend doing it but now you've done it I'd just say check it regularly to be safe.
Never done it, just get an expanding wedge variety, why risk it, invalidating warranties and directly going against the manufacturers recommendations for a few quid, doesn't make sense to me.
Another candidate for the Darwin awards!
The stem clamping over the outside would counter act the expansion force from the star nut.
It's not the expansion force which is the problem - if anything an expanding bung will give more of that - but the gouges which you put down the steerer tube which will act as stress risers.
Before I realised that you needed an expanding wedge type plug, I once tried to get a star fangled nut into a carbon steerer and just couldn't physically do it without the steerer edge starting to splinter. I realised something was up and got advised that a wedge was the way to go.
So I thought it was as much to do with actually getting one fitted, as any issues once fitted?
I've been on this journey... the last post describes the problems well.
I tried a number of recommended steerer bungs:
- M Part. this was okay but the bolt wasn't long enough
- Deda. very lightweight but the bolt was far too short
- Pro (by Shimano). Perfect. Lightweight and of great quality
i've seen carbon forks break at the dropouts or the leg but never an upper steerer
I've seen a upper carbon steerer fail and fortunately it happened at fairly low speed, the rider still went down like a sack of spuds though. Steerer had a bung in it not a star nut.
I had a numpty moment a while when my road frame turned up and I put in a star nut as I had forgotten to order a wedge type and was due to go on a pre arranged ride.
It's been fine, the problem is once you have one in there you'll probably do more damage trying to remove it. Best just to leave it in.
Starnut or bung is only used to apply pre-load to the headset bearings before the stem is tightened. Once the stem is tightened the starnut/bung is obsolete, you can even remove the top cap as everything is held in place by the stem.
If you have done it then, just leave it in but check for cracks around edges at top of the steerer tube as this is the place where any will be.