I've got stubby little legs with a 31" inseam. I'm pretty borderline for 170 or 172.5, have been using a 172.5, and I've recently been wondering if I couldn't improve cadence and efficiency by dropping to a 170mm crank. Then, on a long bomb down mountain roads last night, it also occurred to me that this would have the side (and even more pronounced/beneficial) effect of giving me another 2.5mm of saddle height and thigh clearance to get tilted even farther forward more comfortably...
Sound reasoning, no? Any reason I shouldn't expect to be able to flatten out a little better after shortening my stroke diameter a full 5mm??