Loosen the top bolt of the stem until it sticks out of the stem but isn't fully out of the wedge threads. Smack with a hammer. It should pop down and then the stem should move freely. If it doesn't start using penetrative oil from the top and the bottom and let it sit in both orientations for a day.

If you're still having trouble you can come by and I can see what's what. I have the headset tools and a couple spare spacers.

Thanks Narhay, I'll PM you if I get stuck (like the stem) :) Hoping a moderate wack will un-stick it. I hate hitting my bikes with anything!

Using your wife's thumb is even worse.

omg!!..ha! or her foot :o

before i got a t-post driver (fencing), i had to use a sledge hammer. wouldn't you know the one time i ask my wife to hold the post steady just so i could get it started, i miss the post and snap the handle. and, it's funny how the hammer head could have gone anywhere, but it had to bounce onto her foot. i think she made it do that so i could be in trouble again. haven't found her book of spells and pin dolls, but i'll keep looking

I have one of these. Love it. Super wide jaws, tight clearances in the mechanism so that the width that you set the jaws stays in place much better than most adjustables, and mine was made in Spain so (hopefully) there's less chance of bad working conditions and environmental offenses. I've used it plenty of times in the situation where only one of my headset wrenches fits and it works great.

Just to be clear, you don't need to remove any part of the headset to remove the stem.

The order of operations here are:

1. Remove stem. Smack the bolt while loosened a bit but still threaded in to the wedge to remove the wedge. Hold the wheel between your legs, then twist the handlebars back and forth to see if it'll break free. If that doesn't work then you start down the path of more intensive removal methods. You already found RJ, but there are a ton of other threads and other online resources about stuck stems out there.
2. Remove top hex nut on the headset.
2.5 (optional) remove the bottom hex nut and fork and regrease your headset.
3. Replace the light bracket with a keyed spacer the same width (pic below)
4. Reinstall top hex nut. You'll need 2 headset wrenches or a headset wrench and an adjustable wrench to reinstall the hex nut and readjust the headset.
5. Clean your stem, the inside of the steerer tube, and apply a very thin layer of grease to your stem before installing to reduce the chance of re-stuckage.
6. Reinstall stem.
7. Go ride before the weather gets crappy!

Bingo, bango, bongo - took all (or most) of your advice and a decent tap on the wood and unstuck the expander wedge. When I took the stem out there was some surface rust so I cleaned that all up, got off that light mount and then greased the heck out of the stem and put it back together. Now I can show off my new handlebar bag which was the real reason I wanted the mount off. :)
thanks all
https://cimg7.ibsrv.net/gimg/bikefor...7f5d10d68a.jpg

I thought you loosened your headset locknut, and you didn't have a headset wrench to adjust the headset correctly. Make sure the locknut is tight. And without the front wheel mounted, make sure the steering is smooth, tight and not binding.

The light mount was a very thin sheet metal (1mm?) and it sat between the headset locknut and the head tube so I don't think it required a spacer? I didn't need to remove the front fork or wheel. I have a decently thin adjustable wrench which I sized correctly for the headset locknut and gingerly tightened it back on with the wheel aligned correctly.

I didn't read Tricky's reply until just now which is too bad because I could have done further maintenance by removing the bottom hex nut and forks and lubricating that. I can save that for a later job.

Good looking machine you have there!

That's not how you do it. Read my post again. Study how to adjust a headset. You basically need to lock two "nuts" together on any system like this (whether it be a headset, hub, pedal, or bottom bracket). Or you can just hope for the best and maybe replace the headset later when it fails.

As with many endeavours mechanical, you have to develop the requisite skill and experience that gets you to where you intuitively know when to switch from careful mode to hammertime, sometimes there's a lot of ground in between and sometimes there's not.

Always proceed with caution while looking for the opportunity to get after it when necessary. ;)

Yep, same here, these are great when you need them. :thumb:

You need to make sure there is a gap here, hence the reason you may need a spacer when you remove the bracket. If the nut bottoms on the steerer tube the headset won't hold adjustment and F things up.

https://www.parktool.com/assets/img/...elp/fork22.jpg

Ok, does RJ cover what you're referring to in this video? If so, you're right, I didn't even notice that nut. I will need to get that wrench he has.

Thanks, let me know if you're ever interested in going for a ride some time I can carry the snacks! :)

[MENTION=518431]gthomson[/MENTION] looks like the image of the keyed washer didn't come through in my previous post. You need to have a washer with a key in it in place of that light mount. See below. Notice that little nub at the inside top of the washer. If you don't have that the headset will become loose over time. Your old light mount probably had a key in it for this reason. If your headset is adjusted well right now (no binding from being too tight or rocking back and forth) it would be enough for a little bit of riding but plan on trying this again with a second wrench and a new washer once acquired.

https://external-content.duckduckgo....jpg&f=1&nofb=1

Thanks Tricky, I will get the washer then tighten the headset from both sides. Is there a specific size the spacer should be?

​​​​​​Thank you for the tip; I think I'll roll me over to NAPA.

In my personal experience with threaded headsets that I put through a lot of abuse (mainly an 80s mountain bike commuter. curb hopping, light offroading, 1 CX race), they eventually came loose without a keyed washer. Saint Sheldon felt the same way too ("Keyed Washer" in the Washer section of the Glossary) Sheldon Brown's Bicycle Glossary W I think you can get away with not using one, but adjusting threaded headsets is one of my least favorite bike maintenance tasks and I would prefer to do it as little as possible.
[MENTION=518431]gthomson[/MENTION] re: size, if you mean thickness, then if your headset was staying tight when you had the light mount, then just match the thickness of the portion of the light mount that was sandwiched between the two mounts. If you mean circumference, then yes, there are a couple different sizes, but a bike shop should be able to easily supply one for your standard 1" threaded headset. Or, just YOLO it without a keyed washer like SurferRosa. Heck, if it's staying tight now, then you can run it that way too. You do you! :)

I'll defer to your judgment. I don't have any experience abusing road bikes.

You mean you're just riding bikes like a sane person? For shame