"Sharing the road means getting along, not getting ahead" - 1994 Washington State Driver's Guide
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Just wanted to say that Specialized has a life-time warranty on their frames and I just had a very small crack in my 6 year old bike and they give me a whole new bike, delivered in less than a week. Great customer service!!!
I have a friend who is 4'10" and she rides a tiny Lemond Big Sky road bike. I'm not sure of the size of the bike but it takes 700c wheels. It's aluminum w/ carbon fork. She has done many century rides on it. She is now thinking about a custom frame.
I'm not sure if they still make the Big Sky, maybe they might show up on ebay.
Specialized Ruby
Gunnar Sport
Salsa Vaya Ti
Novara Randonee x2
Motobecane Fantom CXX (Surly Crosscheck)
Jamis Dragon
There are a lot of great small frame bikes, but a lot of them are not going to be found used. So, that is good that you are looking new. Also, go get fitted. I thought I was in your range (same height as you) and I am a 47 cm girl on my Trek and a 50 in giant's OCR series. Just really depends on the geography. I am all legs, so I take a taller bike, but you may be surprised!
As Eden mentioned, it's all about proportions rather than height when you're small. For example, I have a friend the same height but she has short legs (so standover is her critical issue; she rides a very compact 700c Giant) and I have long legs/short reach (so effective top tube is my crunch number; I ride a custom 650c).
It's very difficult to find xs bikes to try, but keep trying as you will learn what geometry suits you. Or get a professional fit as already suggested (if you're a member of club, they might be able to recommend someone reliable). The geometry of your current bike is a good start if it fits (get the data from the manufacturer's website or see Park Tools on how to measure a frame). Key measures (depending on your proportions) are top tube length (your reach) and standover (which you can measure easily anyway). Once you have a feel for those, you'll be able to assess anything that comes up and shop the main brands' websites for what's likely to fit. Good luck.
Cannondale makes ws bikes that start at 44 cm.