Originally Posted by
dddd
At some point perhaps in the late 1980's or early 1990's, TTT's published bar and road stem diameter became a "proprietary" 25.8mm.
That is interesting. I don't really remember the proprietary 25.8mm, but this was towards the end of my wrenching days. Either I forgot, or didn't notice, or it came after my last LBS job. It had been hammered into my head for years that 3TTT was 26.0 and Cinelli was 26.4mm.
I suspect your theory that this was done for legal reasons is correct. The late late 80s to early 90s was a period of a lot of experimentation in bars and stems, and much of it was frankly pretty wackadoodle. There were those terrible early anatomic bars, split stems, lots of stupid stuff. I can see how they wouldn't want the liability of people mixing their bars and stems with those made by other manufacturers.
I find it very hard to believe that 3ttt really changed the actual size. Obviously this could be verified by measuring.