Hi, I have picked up a new bike today and had a bit of a disaster! I have looked online and tried to usual hitting, tipping etc but this seems like a particularly unique case...and please don't ask how it happened because I have zero idea!

Anyway I took the top cap off, loosened the bolt unknowing the consequence was that it would fall to the bottom of the tube. I have somehow managed to get the metal part of the expander, however the expanding parts are stuck and even more confusingly the bolt is stuck under them. You can't access the head of the bolt because it is partly covered by the expanding parts.
I've tried using a long Allen key to get in to it but no luck and have also tried slapping, tipping, hitting etc.

Does this have any impact on using the bike or is it purely a bolt to attach the top cap with and more a cosmetic issue? I have taken photos but it won't let me upload them as I don't have enough posts!

Thanks for any help!
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Also, just noticed there was a bike mechanics forum that this would have been better in, sorry! If it can be moved by an admin then please do!

Here is the link to your gallery with your photos - https://www.bikeforums.net/g/album/18036484

You have a threadless stem, the stem cap, as well as the 2 bolts for the stem are required. I would not recommend you ride the bike without top stem cap since it helps keep the headset/fork from developing play. It wasn't very secure previously if the star nut fell when you removed the bolt.

I'd slide the fork off the frame (may have to unhook your brake) and shake it upside down. Steerer tubes are also hollow so you may be able to access it from underneath.

Thanks for attaching the photos! They have obviously duplicated and meant to only be 3 photos.

Do you think a bike shop would be able to get it out? I just can't get any movement on the parts stuck inside at all

Most likely, they'd also be able to install the star nut properly. Hopefully your shops are not overwhelmed and have a long waiting period for maintenance.

I don't know what material your fork is, but you maybe able to use a telescoping magnet or a wire coat hanger to move the bolt around if you can't shake the fork upside down.

It is full carbon, would that work? Is removing the brakes difficult or fairly straightforward? Thanks for your help!

Depends on your brakes, and how mechanical you are. You can try turning the whole bike upside down first. Carefully because the fork may slide out of the frame, especially if your stem is off.

in your place I would fashion a small hook out of a wire coat hanger, or even use a spoke, and reach down to hook under the rim of the expander and pull it out. Or, if it’s not rattling around, you could get another expander from the LBS and just leave the old one there for now - it’s doing no harm

Yea good point about buying another one actually. Thanks everyone! I've ordered a telescopic magnet so that's the first attempt and then take it from there!

Maybe chewing gum. Seriously, the magnet may like the more massive pieces of metal better. Something sticky on a stick may be able to retrieve the errant part. Another alternative would be to run a loop of thin supple string like fish line down a tube and snare the part, then tighten and retrieve.
Good luck

I don’t totally understand what you are trying to say but in general the expander in the steerer tube cannot be pulled up out of the tube easily. It needs to be pushed down to remove it. You may have to use a wrench extension to hammer it out. Of course you need to remove the front wheel first. Is your steerer tube open from the top to the bottom?

You are corect; it designed to hold when pulled up.

As mentioned above, either push it all the way through if possible, or just push it out of the way and put a new one in.

Just turn the bike/fork upside down. It should fall out. It may need a gentle tap if the steerer tube ID is tapered. It isn’t a star nut that only goes one way. Those you have to push through or drill out.

think about it... everything just fell down. It is loose.

John

Edit Added: If a gently tap doesn’t move it, find someone with a knitting needle/crochet hook and help it along.

Too many people in this thread don't understand the difference between an expander plug(used in a carbon steerer tube) and a star nut(used in a metal steerer tube) and keep giving advice as if the OP has a star nut stuck in the steerer. There is no star nut involved here. The expander fell down into the bottom of the steerer tube and the tube diameter probably gets a bit smaller at the bottom, so its stuck. Turning it over and hitting it may free it or he may need to hook it with something to pull it out the top.

bumping this thread because I'm having a the same issue. OP, did you figure out a way to extract the expanding parts or did you end up pushing everything to the bottom?