Cinelli LA84 x 3TTT stem troubles...

Day 1 of building up my current project and I already have some troubles:

As you can see the stem should be a mm or 2 bigger. No problem, for a regular stem...

Here you see that the 3TTT stem I have has a sort of internal bolt for tightening the stem (you need to place another bolt on this to close the stem). Because the internal one is pretty small all the tools we use to try to open it with bend.

Does anyone have an idea on what to do now? Try harder? Sell the bars? Sell the stem? I'm lost

After some research I realised I'll just have to look for a smaller handlebar or bigger stem...

As far as I know, LA84 were only available in the old Cinelli standard of 26.4mm; they were not re-issued in the common 26.0mm size.

3TTT stems are generally 26.0mm, but I have also learned that they did use 25.8mm for a time.

I've got a 3TTT stem with a similar looking arrangement (difficult to see from the photo): a small bolt screws into the stem and then another bolt screws into that.

I've not figured out what this arrangement does: the second bolt closes the clamp, but the first bolt doesn't appear to do anything.

3TTT do have various arrangements to allow you to open the clamp, but if this is one of them, I don't understand how it works.

Either way, what you need is a Cinelli stem, in the old 26.4mm size.

If you are in love with the stem for this build and don't mind 'ruining' it you should be able to use a round file to enlarge the inside diameter. I've done it with a 25.4 up to 26.0.

I've done a fair bit of coke can shimming

Also .45mm brass is easily available and can be cut with sharp scissors, or tin snips

I've got a 3TTT stem with a similar looking arrangement (difficult to see from the photo): a small bolt screws into the stem and then another bolt screws into that.

It's also such a system, no idea why someone would design this...

If you are in love with the stem for this build and don't mind 'ruining' it you should be able to use a round file to enlarge the inside diameter. I've done it with a 25.4 up to 26.0.

Hmm, that could be an idea

Febrile: I don't understand your comments (non native English here...)

Febrile is talking about the opposite of the problem you have: when the stem is too big for the bars.

Not sure I'd be happy messing with the stem: it would be difficult to keep it perfectly round, which could lead to stress points and possibly failure!

26.4mm stems are plentiful, but of course you'd have to look harder and pay more for one with a Concorde logo.

I'm not a fan of "pantographing" though, so that wouldn't bother me.

you should be able to use a round file to enlarge the inside diameter. I've done it with a 25.4 up to 26.0.

Hmm, that could be an idea

If the 3T stem is 25.8 mm it should work with bars that are 26.0 mm.
As with regard to shaving off metal thickness, if you must, I would suggest sand blasting with 120 or 250 μm at 2.5 to 4 bars pressure. I know, probably sound too specialised, but it's a nifty way to remove a relatively uniform layer of metal without introducing too much stress into the alloy. If you know a dental technician/ dental lab they have the equipment, and most lab use the sand blaster on daily basis.

What did you do in the end: new stem or new bars?

I'd be interested in the bars.

Second on the bars

I got my LA84's into a 26mm Nitto.
Try this method, put a coin or something and use the screw to open up the clamp area. http://janheine.wordpress.com/2012/01/17/inserting-a-handlebar-into-a-stem/

A neat trick but with the OP stem, I doubt there is enough room to get a nut and coin in the gap.

However, using a stem too small for the bars isn't a good idea, unless you like going to the dentist...

Scilly I have a 26,4 stem for you if you want. or a 26 bullhorn to tread... PM

why don't you get an inverse shim?

why don't you get an inverse shim?

Please explain

Please explain

Its an age old joke, there is obviously no such thing. You can never shim bars or stem to make them smaller.....

Give that coin trick a try.