I'm no expert on touring bikes. My take on why they are more comfortable, and others can correct me and add to my knowledge, is as follows:

- Tend to have steel frames, and usually a bit heavier steel, and a ride that is more forgiving.
- Tend to have longer wheelbases which also smooth the ride at a compromise in quick handling.
- Tend to have relaxed head tube angles.
- Many tend to have larger tires & more clearance in the forks. The Trek 520 and Fuji touring bikes come with 700x32 tires as standard.

The Poprad is not a touring design. It does have a steel frame, which strikes me as a positive for riding cross, but it's a light one. It is a bit longer, but not as long as touring frame. It's head tube is a bit relaxed, but again not like a tourer.

The Poprad is a racing bike and I just don't see where it comes off as a comfort bike in its geometry. Perhaps it is a bit more comfortable than a road racing bike. But I don't see where it would be so much so that it would have a substantial impact on the sizing.

Personally, I think that given what the OP said about his measurements, that the best Poprad size for him would be the 59 cm. But I could be wrong. I also base this upon my experience in riding a LeMond 53 and finding it a reasonable fit ... and I'm much smaller than the OP. His Rivendell PB measurement is 5" longer than mine. The Popard 55 has a standover of 80cm, and his PB is 88, so that puts him 3" over the top tube. Usually that is a bit small. But if he has a shorter torso & arm length than would be typical for his inseam, then he may better fit the smaller frame.

If one has a traditional geometry bike, and the buyer is a normally proportioned man (which isn't all that normal), a 55cm bike is fitted to a man who is around 5'8". As the LeMond 55 is really a 56, as most companies would size it, then I'd expect it to fit a "normally proportioned male" who is 5'9" to 5'10".