The technical differences between these three design configurations are derived by three primary considerations influenced by where and how you plan to ride:
1) Average surface finish
2) Average speed
3) Expected abuse
It's pretty obvious how these are all related.
A smoother paved surface has less rolling resistance and greater predictability which leads to faster average speeds with less abuse from high and low frequency shock. Higher speeds encourage a slightly lower riding position (you actually have 'lift' support from air), which places your center of gravity a little lower and more forward (your CG, not saddle position), so you will want the handling to be a little more precise to maintain that locked on a rail cornering at higher speeds. With the lowest demands on durability of the three types, the Duetti would build up the lightest as well.
Conversely, coarser surfaces lead to slower average speeds (though perhaps higher heart rate from excitement). At somewhat slower average speeds, a slightly higher riding position is not only more natural, but a cyclist's agility–the ability to move the bike quickly to maneuver out of trouble–is improved from a somewhat more upright position. The front-end geometry of the bike is adjusted to increase stability to the expected speeds and durability is increased as the bike will be facing more high and low frequency shock and vibration, so over-all weight will increase slightly.
Why don't you publish geometry charts?
We don't publish geometry charts because every bicycle is design-optimized for the only cyclist that matters, you. Your size, strength, position on the bike and of course component selection all drive the geometry in a frame and fork. We begin with understanding where and how you sit on the bike and then design the right bike underneath you. Sharing a geometry chart as most companies do, is only useful if we were making a limited number of sizes designed for nobody in particular. We can't design your next bike without knowing you! Our deep understanding and interpretation of position, fit, balance and design parameters, is what sets us apart from the peloton of fitters, designers and builders.
20 Prospect St. Suite 215
Ballston Spa, NY 12020
(518) 309 4159