Lynn,
I know that many 1970's Raleigh Professionals came equipped with 3ttt Record stems and GB "Map of England" engraved bars. I have a set of those bars and the clamping area measures just shy of 25.4 so my guess to your question is that 3ttt made stems with the larger size opening for their own bars but also with a smaller 25.4 opening for standard ISO bars.
Eric Elman
Somers, CT
>I bought a NOS TTT Record stem like the one I already had on my red
>Lejeune, only difference being, I thought, that it was longer. So imagine
>my surprise when I found I could not get the clamping portion of the bar
>into the clamp. Whip out the trusty digital calipers and find the stem
>clamp runs 25.4mm to 25.6mm and the bar clamping area is 26.0mm.
> So is the stem made for a French bar? The quill is 22.2, so I am a bit
> perplexed. I hesitate to try spreading the clamp area fearing that the
> stem will break or else the clamp screw will not line up.
>
> Ideas?
> And then there is the Belleri stem I bought that won't go into my French
> 531seat tube. We will save that for later.
>
> Thanks.
>
> --
> Lynn Travers
> Hazelwood, MO