looking at Josh Putnam's pages has got me thinking about rear triangle geometry...maybe i should lengthen the wheelbase by extending the stays. this would give more stability, but decrease stiffness and slow acceleration.
much of my design thinking so far has been based on the work of Suzy at LIttle Fish Bicycles, http://www.littlefishbicycles.com/
her pdfs of autocad drawings in particular have been really helpful.
furthermore, all of my recent cycling experience, really most of my cycling experience, has been on my 06 Bianchi San Jose single-speed ( http://www.bianchiusa.com/06_san_jose.html ), which is based on the Bianchi Volpe.
all of these (Suzy's and mine) aren't built for the kind of fully-loaded, full-fender touring i want to be able to do on this thing.
fortunately, i think i can keep the same main triangle geometry while making changes to the rear triangle, by using longer stays. it's a question of compromise. i need to look at other touring frames to see how they deal with this.
trek 520 21" vs Bianchi San Jose/Volpe 55cm
520 wheelbase is 38 mm longer, 1054mm vs. 1016mm
520 has 2mm more fork rake, 52mm vs. 50mm
520: 71.0 HT angle/73.5 ST angle vs. 72.5 HT angle/73.0 ST angle
520 has 25mm longer CS, 450mm vs. 425mm
the 520 is a shorter, longer bike.