nixage said:ABSOLUTELY CAMPY ONLY. 😉
Pegoretti's geometry seems a little strange at first but what I think he is really doing is dropping the top tube down a bit. Since head and seat tube are the same angles this in effect keeps the top tube at the same length and makes it look like the head tube is extended.
I'm actually currently riding an old MX Leader with 59cc seat and 57.8cc top tubes. A little more stretched out than I'd like to be. My look KG461 is 57cc for both seat and top tubes and seems to fit better. That's why I was wondering if I couldn't go smaller with the Pegoretti (ie. 56) and still be comfortable. I guess I won't know unless I try. But like you said, if I'm not happy, I'm pretty much srewed and I'm not riding for anyone so I will be.
Actually, it isn't that the top tube is lowered on the Pegoretti, the top tube is in the traditional, horizontal (as in, parallel to the horizon) position ...
I think that framebuilders like Litespeed have also gone to the extended top tube on some frames to preclude the rider needing more spacers than are safe -- in the past, the additional centimeters in the stack height were accomodated by the locknuts in the threaded headset ...
See if you can "borrow" a shorter stem and put that on your current LOOK frame ... check out how the LOOK frame feels with the shorter stem ... heck, it's worth $20-to-$30 to buy a used stem & bars off of eBay to test the fit ... OR, you can certainly use a longer stem on the 56cm Pegoretti if that is the size you get AND you decide it is too small.
Your MX Leader frame should have a stem that is about 1cm shorter than the one on your LOOK, but it sounds as though it isn't ...
FWIW. I have multiple frame sizes, but on all of them, regardless of the top tube (and, seat tube) length, the NET cockpit fitting is the same -- I set the saddle relative to the crank ... I then adjust the handlebar reach (more, the reach to the back of the "horn" on the brake hoods) to within about a centimeter of the distance from the rear of the saddle (an arbitrary point of reference for me to use) ...
To achieve that end, I ended up buying stem lengths from 90-to-130mm which were subsequently swapped while the bike was mounted in my trainer (and, road miles) to find THE current, optimum fit (for me).
Once you do find your preferred bike fit, the seat & top tube lengths become more a matter of aesthetics -- that is, some people like more seatpost exposure than others -- if one remembers to maintain continuity in the actual fit.