Look here, I could get a whole 5 degrees of hip-angle-opening-joy by forfeiting a mere 5 mm in crank length! Imagine if I gave up 10 mm of crank length. My knees might also get to enjoy to 'friendlier' range of motion associated with the shorter cranks.
I'm comforted that according to Sheldon Brown, there "doesn't seem to be any deleterious effect from shorter cranks" I assume he means physiologically, and not in terms of race performance.
I've never given too much thought to crank length, but now that I am, I don't know why I didn't use shorter cranks when I was struggling to get into a proper aero/TT position in my triathlon days. My thighs would come uncomfortably close to my chest. Perhaps that tight hip angle contributed to my current predicament, a superior anterior labral tear and detachment.
