Does it make more sense to fit by effective top tube or by reach? Of course, ideally I'd fit by test riding a bike, but it's rare that an LBS has every size in stock for a test ride -- especially

The Some Double-Cross geometry: Double Cross Disc | SOMA Fabrications


If I compare the 52cm frame to the 54cm . . . the 54 has a longer effective top-tube, but both have the same reach. I guess this is done by relaxing the seat-tube angle and increasing the head tube length. What does this mean in terms of fitting the bike to a rider?

I'm sure I could fit into either frame . . . but if I'm guided by effective top tube, then the 52cm is close to my current bike. If I let stack/reach lead the decision, then the 54cm is closer.