I'm planning on doing a surprise build for my wife. She's got a pretty crappy bike, and I'm looking to build up a nice old mixte for her. I've got a couple options on the line, but the sizing is driving me nuts. I've never dealt with mixtes and they frighten me with their unfamiliarity. She's 5'5" with a 30" inseam, and my best pick right now is a 21" seat tube length Raleigh mixte. Will this work out to a 50-52cm on 700 rims? Should I use 650 to lower it or does it not matter because the former wheelset was 27"? I've also got a 19" seat tube Schwinn in the pool, but it includes nothing, and a nicer 47cm seat tube Nishiki which seems too small. Would either of these frames be better options? Any help is much appreciated.