Originally Posted by
T-Mar
Back when I started competing in the early 1970s, it was common practice to transition from Columbus SL to SP at around the 58-60cm frame size. The assumption was that taller riders were heavier and stronger, therefore requiring a stiffer frame made with heavier gauge tubing. In the mid-1980s there was a trend towards increasing stiffness in the bottom bracket area. Bianchi introduced their Superset configuration. This used an old custom builder's trick of employing heavier gauge down tube and chain stays, even on smaller frame sizes. Columbus SLX and SPX achieved a similar effect by incorporating helical ridges into the bottom bracket ends of the down tube, seat tube and chain stays, which increased stiffness with only a small increase in weight. The Japanese approach to increased bottom stiffness in the mid-1980s was to introduce triple butted tubesets, with thicker butts at the bottom bracket end.
Interesting. Makes sense of my casual observations of how some frames appear to be built. For example my '92 Univega Via Carisma (57-58cm frame, best I can guesstimate) with the biaxial power oval frame has a noticeable thinner and presumably lighter top tube. It pings with a clear tone like a bell while the downtube and seat tube sound thicker and dull (partly due to the water bottle cages). When I stick my finger through the frame junction with the seat post removed the tubing feels different between the top and seat tubes.
I've kinda toyed around with the notion of getting a road bike steel frame in a slightly smaller size than I'd normally get -- maybe a 54 (I'm 5'11") -- just to compare the weight and handling. I know I *could* use a longer seat post if necessary. And the lower stem wouldn't be a problem. The shorter reach would actually be more comfortable for my cranky, creaky old neck. Dunno if that's a good plan but it wouldn't cost much to experiment. That's one great thing about some of these older bikes -- they don't cost all that much, and I could resell it if I can't make it fit.