mtnbke- Chill out a moment. Hillrider's comments reflect years of frame design thinking and results. I respectively ask what are your credentials in frame design and building? I don't take any issue with your depiction of Zinn's designs. I do take issue with your treatment of Hillrider's comments. I also am unsure about your statement of "Larger bikes are completely unstable." Certainly very large (as also with very small, my area of focus for years) frames present different challenges the commonly sized ones. Zinn's solutions are but one path.

I have only two data points, during my building, of extra large frames. One was a 72cm the other a 74cm. This was back in the mid 1985 and few were aware of OS tube use (Freddy Parr being one though) in steel bikes. We, Cyclery North, were commissioned to build two big bikes almost at the same time. We use typical racing steering geometry with traditional tube diameters. The walls were thickened and straight gage tubing was used in the TT and DT. The steerers were thick walled 4130 machined out for the stem and threads were chased. Both were built up with strong but common parts (36 spokes and good cotton sew ups). Both riders raved about their riding experiences and neither complained about any handling issues. One rider was a pretty aggressive guy, the other a skinny newbie.

The last addition t this discussion comes from my attending Albert Eisentraut's last east cost building class. the first few days we were lectured on building aspects including design and steering geometry. He said that larger riders with their greater mass were actually more stable. So to get a bike to handle nimbly under a large rider one had to "quicken up" the steering geometry. (By the same token a small rider would benefit from a slower steering geometry. This does jive with my many small frames I've built and used).

I do agree with the smaller triangle makes for a stiffer frame idea. The extra large frames we made at Cyclery North were both hellenics (triple triangles for the young here). here's a shot of the 72cm I made. Andy.