To clarify the posting title: I'm 5'6"ish, and normally ride 170mm cranksets. I have a build I'm planning with a frame I've been offered for free, and some other parts I've been given by other people, and the crankset I've been offered is 172.5mm. I'm fairly particular about my saddle position, but I'm no racer - I just use the bike as my everyday transportation.

If it makes any difference, this frame I'll be using is substantially taller than I usually ride (58cm vintage Shogun 300 with a horizontal TT, vs. my modern sloping-top tube bikes that range from 48-53cm in their nominal sizes). I can stand over the TT with feet flat on the ground, and the TT is short enough that I can comfortably reach the bars, while the frame height brings them easily to the desired height (unlike a 54ish cm vintage Panasonic frame I have, where the TT is quite long, and I need a tall stem with short reach to ride it)

EDIT: For reference, here's a bike with a frame near identical to the one I'll be using (in size, anyway)...I can ride it set up as shown, but this one has 170mm cranks. I'd probably drop the saddle maybe 1/4" if I was gonna ride it for more than a couple miles:



For comparison, here are my current bikes (note the tall/short stem on the Panasonic on the bottom in the second picture):