Can you try them out for more than just a ride in the parking lot? I'm 180 cm and right in the overlap of a 56 cm and 58 cm Tarmac as shown in the manufacturers sizing recommendation. I wound up getting the smaller 56 cm frame and it's great. But now I'm wishing I'd tried out one of the 54 cm frames. The mechanic that sold me the bike told me he thought I ought to get the 54 cm. But I was pig headed as I'd always rode over size bikes comfortably for most of my life.
You do need to double check that you can get enough bar height on the smaller frame though if you don't like a low position. But on my Tarmac, I have only a 10 mm spacer under the stem, of the 30 mm of spacers it came with new.
Last edited by Iride01; 11-16-21 at 02:03 PM.