I haven't read all the posts so I don't know if this has been answered but have you lost height and, if so, is it upper body? When I started riding it was around 1982. I was 36 at the time and I was 5'10 1/2" with a 32.5" inseam. I rode a 54 frame with a 100mm stem and it fit me perfectly. Since then, thanks to aging and a fusion of C1 & C2 thanks to a cycling accident, I have lost almost 3" in height although my inseam is unchanged. I currently have two road bikes. A 55 Guru steel w/100mm stem and a 52 CAAD 12 that actually measures out to a 54 frame with a 100 mm stem. Totally comfortable on both of them. Why nothing has changed I have no idea. Kind of curious if others have had fit change as a result of aging bodies.