Originally Posted by
Don Buska
I hear what your saying TMar.
What was confusing to me was those SR frames (Araya) that both are advertised as using TANGE #2 which should have been 26.6 posts, and even considering that my SR Maxima went to 26.8mm which falls into your +/- 0.2mm, that advertised Pro AM was actually + 0.4mm using the 27mm post. I'm just more of the belief that they, Araya in this case, didn't hold to a true TANGE #2 tubeset on these bikes. Or at the very least Araya was doing some serious reaming (almost making double butted into a triple butted seat tube (0.9 X 0.6 X 0.7).
Well, it could be a custom blend. One possibility would be Tange #2 with a #4, single butted seat tube. Even though the #4 seat tube is 0.1mm thicker in the non-butted section, the fact that it is a single butted tube results in it weighing ~10g less than the double butted #2 seat tube. Theoretically, the single butted tube should also be slightly less expensive, though at least some of that would have been offset by having to stock two post sizes. Still, this utilizes a combination of stock tubes, so is easy and cheap to accomplish, while providing a very small but definable difference to a stock #2 frame. .
Some of the Centurion catalogs show the same thing. In 1984 catalogue, the Turbo (Tange #1) is spec'd with a 27.2mm post while the Comp TA (Tange #2) is spec'd with a 27.0mm post. Later catalogues show both #1 and #2 frames with 27.0mm posts. Clearly all are larger than you would typically expect. Obviously, there was some form of customization taking place.