Originally Posted by border reiver

I am about exactly the same body size as the OP. I have 2 bikes that I ride regularly (i.e. each about 2-3 times per week--Bike 1 when it rains, Bike 2 when it doesn't).

Bike 1 has 172.5mm cranks because that's what came with it. Bike 2 was a custom build so I thought, what the hell, I'll give the crank proportional theory a shot and so it has 165mm cranks.

I "think" I prefer the way the 165mm cranks feel, but that bike is newer and fits me better in other ways, so who knows if I'm being completely objective. What is noticeable is my ability to pedal through corners without clipping a pedal so much.

Bottom line is that even a 7.25mm difference is almost imperceptible. FWIW, I'm also a high cadence spinner. Also FWIW, Cavendish rides 170's.