Bike frame advice : Frame and stack length

Vivelevelo
Vivelevelo Posts: 2
edited July 2019 in Road buying advice
Hey all,

I'm looking to buy a new road bike but need some help in choosing the correct frame size.
Being short in height (male, 158 cm (5'2)) does not really help, though I currently have a racing road bike in size 48cm (center to top).
I like this bike, but would like something more comfortable. With the current one, I feel like I have to overstretch, especially when riding in the drops. Which I don't use too often therefore.
I'm looking to buy an endurance bike which would bring me in a more upright riding position.

After weeks of reading reviews I have narrowed my list down to the following (but this can change obviously):
-Giant Defy
-Giant TCR
-Specialized Roubaix
-Trek Domane

Let's say my current bike has the following approximate measurements (measured myself):

Top tube length: 50,5cm
Stand over height: 72,5cm
Reach: 36,5cm
Stack: 50,5cm
Wheel base: 95cm

My inseam length is 72cm.

Now my question, because after looking at several geometry charts of different manufacturers, I'm confused.
An example of the Giant Defy Advanced 1: I would need an XS frame by simply reading off the chart, but this seems most likely correct.

Its seat tube length would be 41cm
Top tube length: 51,5cm
Stack: 52,2cm
Reach: 37cm


So as far as I understand it, this higher stack length (2 cm) compared to my current bike would bring me in a more upright position (which I'm after), but the reach is strangely enough 0,5 cm longer than my current bike. Maybe this is because the Giant frame uses a different seat tube angle?
How would I know if this frame (or another bike) would give me a more comfortable, upright riding position? Is this possible to read off of a chart? And if so, do I need to look for both a higher stack length, together with a shorter reach in my case?

Also, a Giant TCR in size XS which has a sloping geometry, would have a standover height of 73,1 cm which is higher than my current bike which has a top tube that is not as sloping!

A lot of questions, but hopefully some can give some advice.
Thanks if you read this far :).

PS: I'm not considering to buy a road bike with 650c wheels.