I am looking for help with a '72 Motobecane Le Champion stem. I want to put a longer stem on but....

1. I can't find a allen wrench that will fit the stem. It doesn't look that corroded, but possibly the steel has been flattened to block the wrench from going in. What should I do?

2. I spoke with a bike mechanic about the size of the replacement and he measured with digital calipers (note: I suspect the stem is fully extended). At the top it read 22.08, he slid it down and it read 22.2. So he insisted it needed a 22.2mm replacement. He re measued it and showed me the 22.2 reading.

Also, the original owner told me that this is the original stem.
So....How do I get it out? (could it be stuck?) & What replacement size stem should I get (would like 100-110mm).
Thanks

I doubt that it is the original stem. 22.2 is not a French stem size, and there's the possibility that someone hammered it down. It would normally require a 22.0 stem. Good luck getting it out.

The length of the stem (eg, 100-110) is entirely up to you, depending on how much extra reach to require to feel comfortable.

I'm not certain about vintage 3 ttt stems but be aware, the Cinelli from about that era took a 7 mm hex wrench. It's possible your 3ttt Record binder bolt may be the same.

It's probably not the original stem. Not sure without looking but that model was probably spec'ed with a Philippe or Atax or something. Anyway, if it was original it certainly would be a French 22. 0 quill, I would think. But like I said, the top nut on that Stronglight head set will often take a 22.2, and sometimes the steerer tube will too.

Did the LBS mechanic not try to loosen the binder bolt hex head for you ????

You may find this helpful as long as you realize that he didn't mean to say that French steer tubes have an outside diameter of 22mm.

Hmm, not so sure; mine has the same. My understanding is the fork tube will many times take the larger stem on French bikes, its the hole in the top nut that usually won't allow it.

This one will be available when I find a replacement and switch it out, 110 I'm guessing; your's too short!

Oh, I'd guess 3ttt made French sized stems too...

I have a older 3t and as others have said its a odd size allen. Grab then give it a shot.

dbakl - I know that (some) French steerer tubes will accept the larger diameter and I don't doubt that 3T made some French stems, but I can't imagine the OP's 22.2 stem is one of them.

In my experience, exactly the opposite is true. All of my French top nuts will fit a 22.2 stem, but none of my French steer tubes will unless I spend about 30 minute sanding the stem.

https://www.velo-pages.com/main.php?g2_itemId=33309

Original specs say T.T.T. Record. Stem on bike is stamped 3ttt, mm65, Record.

If the stem is just barely in the tube, would the very bottom of the stem be flared slightly and give the higher diameter reading?

I

Those old 3TTT Record stems use a 7mm Allen key for the expander bolt. To the best of my knowledge they only came in 22.2mm. Certainly, the old catalogs do not provide any options other than extension length. There's very little clearance between a steerer tube and stem, nominally about 0.025mm (0.001"). A metric steerer tube is 0.2mm (0.008") smaller than a an imperial steer tube so a 22.2mm stem will be an interference fit but the difference is small enough that it can probably be forced. The other possibility is that the metric steerer was reamed to take a 22.2mm stem. The first step is to obtain a 7mm Allen key and see if the stem removes normally.

The mech briefly tried a few allen wrenches and couldn't find one that fit.

7mm isn't a common size for modern bicycles, so he may not have had one. Try your local hardware or automotive store.

I have several TTT stems with 7mm allen bolts. A 7mm wrench, unfortunately, is not commonly found in allen sets. It is also right between 17/64" (6.75mm) and 9/32" (7.15mm) so a fractional allen wrench won't fit. A little hunting around on the internet will turn one up, however.

Also, what would the diameter of my handlebars be? The specs say t.t.t. Grand Prix. (I cannot find my calipers)
Thanx

Velobase is your friend here...

Velospace says 26.0

https://velobase.com/ViewComponent.as...8-63ced653abd6

Just go to your local Sears. And I would think HD and Lowes might have them also. If you are flush there is Snap On. If you are a poor college student (as I was at the time) you take a file and reduce an 8mm. I still have it.

If neither a 6mm nor 7mm key will go in, I would suspect ^this^ is the reason.

Hey, I just went through a similar ordeal, with that same type of 3 ttt Record stem. The first thing you should do, is get that correct size allen wrench, as previously advised. Then AFTER you break the bolt free, leave the allen wrench in the bolt head, and give it a good rap or two with a hammer, to loosen the wedge inside. I had one seize up a bit on me, in a very short time, so one that's been installed for years might really need "persuading". I actually ended up swapping the bolts, for more common sized heads, but that just leaves me short now, for another stem. (?) BTW, I've read that it was common practice to just sand down a 22.2 stem for a French steer tube, so your funny measurements just confirm that it wasn't sanded as "evenly" as possible.

7MM allen is a common automotive size, used on brake calipers mostly. Pep Boys should have a socket that works.

Sears has them. Or should. Mine does.

I picked one up at Home Depot, I think.

A socket is of no help, Shp4man.

I use sockets exclusively, ColonelJLloyd.

Allen wrenches married with socket fittings are found at automotive stores.

They're called hex bit sockets. I have both 3/8" and 1/4" drive.

I don't buy them at automotive stores.