CX frame sizing question

Current road bike is a Felt VR3 size 56, reach of 386, stack 595 top tube is 540, was trying to decide on frame size for Felt F3X, size 55 reach of 397, stack 568 top tube of 548, size 53 reach of 384, stack 544 and top tube of 530. My road bike is an “adventure “ bike that I usually ride in the drops. I was leaning towards a size 53 just a little concerned with a shorter stack height. Any input would be appreciated.

When I asked my bike fitter about choosing a frame, he recommended a little shorter and a little higher on the front end. I ended up buying a bike with similar stack and reach, and a super short stem. It’s great, but I think the bars are an old shape, and the drops are a bit deep. At some point I think I’ll be fitting a compact bar.

If your road bike fits well and it has room for adjustments, your cx frame should be pretty much the same size (this can be difficult between brands). The set up on your cx bike should be a little shorter on the reach, a little higher on the stem, and typically a little shorter on the seat height.

Does your road bike have a lot of spacers or is it slammed?

Yeah my road bike fits me very good.

Spacers, it’s not slammed.

You might have a hard time fitting either frame similarly with such a difference in stack on the 53 vs your 56