I have seen several posts that mention sizing a cross frame 1-2 cm smaller than a road frame. Why is this? When you decrease the seat tube length, you also decrease the top tube length. You then must make up for a cramped fit by installing an extra-long stem. It just seems to me that any decrease in seat/top tube (smaller than your road frame size) is asking for an uncomfortable and poor-handling bike, as your weight is now too far forward (short top tube & long stem).
Am I missing something? I am in the market for a cross frame and my road frame measures 57 cm (c-c) at the seat tube and 57.5 cm (c-c) on the top tube. It seems that all manufacturers offer a 56 and a 58. Since I fit squarely in between sizes, I really want to make sure of the correct frame before I lay out the cash.
I think you want the smaller frame for better clearance over the top tube and more agile handling in the rough stuff. I'd imagine the 56cm would be great for you. If you factor in the larger tires, your standover would likely be the same as a 57cm road bike.