I'm trying to remove the stem from an old Peugeot. There is a hex bolt on the top of the stem which I assumed was connected to a wedge. I unscrewed the hex bolt and it came all the way out. I can now look directly down through the stem, down through the fork - there's no wedge in there! The stem and fork turn as one.

Is it possible that the previous owner lost the wedge during maintenance (it wouldn't be the only screw-up with this bike) and the stem and fork are held together only by rust? They seem pretty solid.

06092010187..jpg06092010185..jpg06092010184..jpg

Put the bolt back in where you unscrewed it from with just a few threads.
Tap it with a hammer and the wedge will show itself.

The wedge is still in there- it's just stuck. This is normal.

Take the bolt and screw it back in until it bottoms. Then back it out three or four turns. Tap the top of the bolt with a hammer and the wedge should pop loose.

After that, the stem should turn freely. If it doesn't, it may be corroded and stuck- STFF for solutions on how to remove old, stuck parts.

Let me add that this is an AVA stem. Sheldon says to replace it as it is known for failing.

Exactly right of course, thanks dvs cycles and Jeff Wills. The hammer did the job and it came apart easily.

Interesting, the bearings against the upper race are in a cage, while the bearings against the lower race are loose. I wonder if that was the original design?

I doubt it. The original balls probably came in retainers which makes life easier for bike factories.

The prior owner probably rebuilt the headset replacing the lower balls with loose either because he couldn't find the identical retainer, or because he felt that loose balls would prolong the life of the headest. He might have chosen to leave the top set as original because most heaset wear occurs at the bottom.

No, that's the original design. Loose balls in the bottom for durabiltiy, caged balls (ooohh... bad image) in the top for ease of assembly. The bearings on the top get very little stress. I learned on the third or forth try to hold the fork up while unscrewing the top cup to keep from spilling loose bearings on the floor.

Retainers usually occupy the space another bearing ball could go into.

retainers are advantageous in quick assembly in the bike factory.

good old loose ball bearing headsets...
I had to bring out my neodymium magnet to hunt for them all.

The grease in the headset is essentially a dirty glue at this point, so the bearings weren't going anywhere accidentally

Until you turn around too fast and hit the frame with your chin and knock all the bearings onto the floor. Don't ask how I know this.

Indeed, it is a painful image.

However all of the headsets I've ever worked with that used individual bearing balls in retainers came OEM with retainers both top and bottom. I never came across one factory supplied with a retainer on top and loose balls (sound better?) in the bottom race.

I did replaced the lower retainer with loose balls during overhauls to share the load better and a couple of times to get another season out of a "brinelled" crown race.

Look at the OP's pictures- it's a 35 year old Peugeot. IIRC (admittedly, the memories are 25 years old) that headset came with a retainer on top, loose on bottom. Come to think of it, that's how I spent my teenage years, too.

OK, I have never had to deal with any headset that old so maybe that's is how this one was originally made.
A lot of us did during the time of orthodontia and discovering girls.

AVA made a variety of stems. The one in the OP's picture does not appear to be the "death stem:"

I think that Sheldon Brown said that all of the AVA parts are suspect, including the handlebars.