Evolving from a commuter to a distance rider

I have been commuting for a couple years now. I told my partner I wanted to do a 100 for my 50th birthday (January) and she said, "time for a new bike." I'm not much for new and would rather get a great deal on a used bike. The budget is $1,500. I'm 5'3", what size should I be looking for?

Thanks. I had found the Estrogen site, but not the other. Any thoughts on used over new or vice versa?

Sizewise, I imagine you're in the ballpark of a 48-49cm road bike. Someone just posted a 51cm Ruby for sale, but I think that will be too bike.

In one sense, you will get more bang for your buck with a used bike. But your overall best deal might be to look for end of the year deals or last year's models at your local shop. Thing is, if the handlebars are too wide or the stem's not right, your shop will do things like swap stuff out for you. They should do this for no or minimal cost, assuming you're not doing a component upgrade. With a used bike, you can't do that. Well, you can, but it's going to cost you.

Your shop will also do things like give you free tune-ups for a year or so. After you buy a bike from them, you can pop in and get your derailleur adjusted on the spot. Or leave the bike to get a total tune-up. No free tune-ups for a used bike.

Yet another issue is the bike's warranty. Not gonna get one with a used bike. AFAIK, no bike manufacturer allows warranties to be transferred.

With your budget, you should be able to get a nicely spec'd bike.