Ferrari Bicycle CX-70 Need Help on Size

I'm trying to figure out the correct size for an adult who is 5'4" with a short inseam. The bike comes in 3 sizes ... 44cm, 48cm, and 52cm. We've tried the 52cm and it's way to large. It hits the person in the crouch. The bike has a curved top tube and it's difficult to figure out the size. If this bike were a road bike with a straight top tube I think they would ride a 48cm. Anyone have experience with sizing on this CX-70 bike? The bike is on Ebay. We ordered the 52cm but to send it back and order another is $300 for shipping both ways. We are trying not to order the wrong one again.

 

You might see if your local Sam's Club or Toys "R" Us has one in the showroom for you to try.

FYI, unlike the great Colnago frames, the CX-70 is just a ODM Taiwan bike with a Ferrari decal.

http://www.samsclub.com/shopping/search.do?searchtype=simple&catg=535&simplesearchfor=cx-70&x=0&y=0&simpleitemtype=1

 

The compact frames I've looked at were all sized as if they were a standard frame shape. That is, if a 48cm is their traditional frame size, then likely the 48cm is the same with this design. Otherwise no one'd be able to fit any bike again with all the different designs. ymmv of course.

It looks like a fairly common bike though - the Sams Club option looks good too.

 

WOW. That's good information. Thank you.