5'7" 30.75" inseam.

I sat on some treks today while I was in there for my bike's free checkup and found that my terrible shape has me stuck between 52 and 54cm frames. I have a very long torso and very short legs. The stand over on the 54 was more than enough in practically flat sandles so I know i'd be fine in my duck walkin' shoes. However the saddle was all of 4 inches above the top tube and the reach to the pedals was very long. The reach to the bars however was perfect and I was very comfortable. The 52 felt cramped, but the saddle didn't need to be completely slammed. To compound this problem I'm considering purchasing a frame set and building it myself as my budget would be much happier with that than 2k outright, but I have no clue where I should be at.

Smaller frame, longer stem; as long as it's not a huge stack of spacers too.

No spacers. The stem will be flipped and the tube cut. I prefer an aggressive over the front wheel position. It's how I set up my ruckus and it's how I set up my hybrid. I imagine it's how I'll set up the roadie.

I'm practically your size. you're not stuck in between 52 and 54. you should ride the 52cm.

you're average proportioned.

you need to play around with saddle setback, your center of weight and then move onto the stem length to make it fit properly.

I was told this once back in the day, whether or not it's still true I don't know:

If you're between sizes, go smaller. It's lighter and stiffer.

Sounds good. 52 with a longer stem it is. I assume it's best to check actual geometry numbers when comparing between manufacturers.

Anyone want to suggest a nice frameset for less than 1k?

I didn't think about that but that's a pretty clever idea, and you likely won't hear me complaining about light or stiff.

And, you have more option to "increase" the frame size through stems, different reach bars, seat setback, etc. However, it's hard to "decrease' the frame size with anything other than a hacksaw. Nobody likes being forced into a 70mm stem.

I bought 53's. I am 5"7 with 30 inseam.

I am respectfully of the other belief - that larger frame (which will typically have a taller headset) will be a little more comfortable. Though with the myriad of handlebar shapes/designs it's not as critical.

BTW it might take you 1000miles to determine based on your current flexibility.

The time is something I'm prepared for. It's one of the reasons I'm inclined to spend 800 or 900 on a 1.2 or 1.5 and just ride the crap out of it until I have a better idea. I learned a lot from my hybrid about what position I'm the most comfortable in but my noobish mind doesn't entirely know how that translates into a road frame.

I ride 50cm and 52cm bikes and I'm 5'7 with 30.5in inseam

they both have around a 53cm top tube.
catch with my fit is that I seem to have longer than average femurs and bikes in this size have steep seat tube angles, so I tend to require 28~32mm of setback from the seatpost to get a proper fit.

what's important is seat tube angle, top tube length and head tube angle.

I think I probably have a fairly short femur. I don't know though since I don't know what femur length should be for my height.

When I sit back to back with my buddy that's 6'0" our heads are level, I just have 5" shorter legs.

When I got fitted the guy said to go with a slightly smaller frame and run a 120-130 stem with a tall seatpost. Getting more of the carbon seatpost out of the frame makes it much more comfortable. And the smaller frame allows for more drop in the bars plus saves a little weight. He atually mentioned fitting the frame off the stem length which seemed weird.

That is considerig if the size smaller can be fitted properly with those constaints, and you dont have a freakishly long torso or something.

I am also 5'7" with a 30.5" inseam. My torso is long, with broad shoulders and large (for my height) size 10 (45 Euro) feet. I was also torn between a 52 and 54 frame (CAAD9) but ended up with the 54 size. This just felt more comfortable for me and I have less issues with toe overlap.

I would have each adjusted as close a possible by the LBS and go with whatever feels more comfortable.

I'm also rocking a size 9-10 foot which is certainly a bit big given the circumstances. My shoulders are also fairly broad. It's sounding like 52 is a better way to go.