I'm either built weird, or my Mixte is set weird. Because I am 5' 11" male (in shoes 6') and I ride a Fuji Mixte that has a 19 1/2 inch seat tube, and have plenty of room to be comfortable. Granted I changed the handle bars to North Road type bars, and the seat is thick padded seat off of a cruiser type bike, but I still have about a fist worth of seat stem showing when the bike is set to my liking.

The funny thing is, the geometry of the Fuji Mixte seems so laid back, that even when it had the original seat and drop bars on it, I still felt comfortable riding it. I think with the laid back angle of the seat tube that most Mixtes (not all) have it gives the illusion of a longer virtual top tube length even though the seat tube doesn't need to be as long in order to connect to the top tube that's not there anyway. On a diamond frame most of the time the larger the frame the longer the top tube, and therefore the longer the seat tube. But, a Mixte can have a long virtual top tube length and still not have a long seat tube because it's not needed to complete the diamond. Or, at least that is what I think anyhow. There are so many variations on the "Mixte" frame that I've seen it seems everyone of them is a little different than the others.