Star nut removal

I am trying to remove a stem from my frame. The star nut in the steer tube is just turning and I am unable to remove the bolt holding the stem down.
Any ideas?

Bash! Bash! Bash!

Tools required: Hammer, Long screwdriver or solid metal rod
Time required: 20 seconds

Sounds like the bolt/starnut has threaded. In which case you need to bash the star nut out from underneath. Which will be tricky. But as Dovvles says involve hammer work.

I can't hit from above due to the cap. I can't hit from below as it is a carbon fork. How can I get to the star nut to hit it?

I had to do exactly that recently, got a long thin pole of metal (was a long solid tent pole for an old tent) and just bashed the bugger out. Took about 30 seconds of tapping, didn't want to break the pole in there!

Edit, I had a hole at the bottom of the forks for access, no idea how you're going to get at it.

cant you take the cap off and hit it?

can you loosen the bolts on the stem so its just held in by the star fangled nut and bash the bottom of the stem (turn the bike upside down, use rubber mallet/protective overing to save stem).

Options:
If you can hack saw off the bolt head, remove the cap, and hammer the nut out of the bottom of the steerer.

Find something long enough to bash from under the forks, avoiding the fork legs.

Or n3lsons suggestion. which would work really well if you had a bench clamp.

can you loosen the bolts on the stem so its just held in by the star fangled nut and bash the bottom of the stem (turn the bike upside down, use rubber mallet/protective overing to save stem).

I can't hit from underneath as there is no hole (carbon fork). Only way I can see is as said, loosen stem and hit that.

If the bolt is undone enough that the head clears the cap, saw off the head. If not, drill out the bolt and then remove the cap.

Then either go at the shaft of the bolt with mole grips or something to wrench the star nut out or just drill the shit out of it until you can pick it out.

okay..i will give it a go..thanks for all the advice!

Star nuts are not really design to be removed. The shaping of the star prongs means it will only go down not up in the steerer. If it really is stuck one solution is to drill out the thread on the existing star nut to clear a new threaded bolt and insert a new starnut one over the top when you figure out how to get in there.

^ erm, sometimes you make a mistake* and they lierally fall out. in this case I had to hold the bike upside down to make it drop ;-)

tightening the top cap bolt to adjust the headset I found out - well tardy - that the converter around the 1" steerer tube (thick, alloy, starnut bent quite a bit to get where it was, tightly) wasn't actually pushing the top headset ring down properly, just touching the fork tube top

argh. gotta get a new starnut in the morning and try again by daylight!

Why has no-one asked the op why he is using a SFN in a carbon fork?
I figure the fork must be fully carbon as most carbon wrap and carbon leg/ali steerer forks that I have come across have had a pretty standard aperture at the bottom of the steerer.

..

Can you stick something up from underneath to catch the SFN from turning? Long screwdriver or coat hanger wire?

Normally:
I've taken out a few with just a pair of needle nose plyers. Just grab one of the fins of the SFN with your plyers and twist. The metal is strong, but very brittle so it will normally just snap off. Once you take of a few of these you can knock the think laterally and it will fall out sideways.

Another way is to get a handfull of drill bits and go bigger till you kill the SFN. I once had an old Rock Shox fork that had a SFN in each end of the steer tube, the extra was to hold a fender so knocking out the back was not an option.

Some carbon forks have a Steel, Titanium or other Alloy steer tube. I've seen SFN in all of these, but it's a big No-No to use them in Carbon Steer tubes.

I had a similar issue with carbon forks/aluminium steerer recently. Took it to LBS for help.
The guy there just bashed the original one further down and put in a new one over the top.

Obviously this only works once you have got the cap off - which leads you back to the hacksaw or the drill..