Be very careful and take a good long test ride and make sure that they have a good return policy if the frame does not fit. Some discomforts take a longer ride and not just sitting on the bike in the shop to show up. The neck and shoulder pain I used to get from a too large frame would usually only show up after 2 hours so would be pretty hard to duplicate in the bike shop.
Fit is all very personal, but I think a 48 or 50 sounds like it might be a bit big on you? I am 5' even with a 29" inseam and I ride a 44cm frame. Several caveats it definitely sounds like I have a shorter torso than you- I ride a small frame because of reach issues and not all frames of the same "size" are equal - you really need to compare overall geometries and not just the listed frame size. Top tube length, which is another important aspect of fit can vary widely on frames of the same "size" as size is based on seat tube length. You should be able to stand over the top tube with at least an inch of clearance and you shouldn't feel either stretched out or cramped up to reach the handlebars. You should be able to sit comfortably with your elbows bent and loose. If your elbows are straight and locked the frame is likely too big.
As far as computerized fit calculators go -my measurements plugged into the fit calculator of a fancy smancy to be unnamed Italian bicycle company (no its not Bianchi) come up with me fitting a 49cm or 50cm, but I think that the only reason for it is because it is the smallest frame that they make! The interest not being in my comfort, but in selling bicycles. Some bike shops do use software that is not related to any specific brand of bike, but I don't know how effective it is. Just make sure that you trust the person at the bike shop to be putting you on a bicycle that really fits, and not just trying to sell you what he stocks or happens to have around.
Anyway not to scare you, but I've been there. I used to ride a larger frame from back in the bad old days when no one actually made a smaller one and to tell you the truth I did not know until I actually rode a bike that fit me what I was missing. I really used to think my old bike was great and I resisted change for a long long time. With my new bike I am more comfortable, considerably faster and can climb hills. I grew up in Pittsburgh so I know that comfortable hill climbing will be a good thing!



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We futzed with it and it works, but ideally should be one notch smaller.

