I've bored plenty of people on a few forums with my crank length sagas before, so I'll keep it short.
I'm 181cm with long-ish legs (89cm inseam) and size 43 feet. My regular crank length these days is 172.5, for no good reason other than that was the most available length on the used market when I was decking out 4 or 5 bikes a few years ago. After a failed 12-month experiment with 180s (3 sets on 3 bikes, so it was a bit of an investment back then), I was looking for 170s (I might've even settled for 175s), but I was broke, and there was heaps more Dura-Ace 10sp 172.5s around for better prices, so I settled for that length.
However, I still often race criteriums on 177.5s, because I like the feel of stomping out of corners and over short rises off the saddle with the long levers. I dunno if it works, science wise, but it feels good. Maybe it's a placebo.
I used 180s around 2005 for about a year, but I could never get comfortable with my knees coming up too high, and maybe the extra reach bothered me, too. I was a bit fatter then, so it didn't help having a little belly in the way. Then there's the whole aero thing.
When I had a persistent sore knee at one stage with the 180s, I used another bike with 175s, which I had ridden for a year, and on my first ride on it, not only did my knees not hurt, but I rode like Superman.
This obviously got me thinking about getting rid of the 180s, which I did a month or 2 later. I did miss the 180s during certain rides on short "off-the-saddle" climbs, so I got 2 pairs of 177.5s, hoping they'd be more comfortable, while still feeling as though I had the leverage if I wanted. I'd lost a stack of weigh by then, so the 'fit' was much less of problem.
Sory time:
One of the strongest riders in Melbourne is former multiple Olympic and World Champion rower, Drew Ginn. He's a farkin beast. As far as I know, one his early bike races was the 2010 national road TT, where he came 6th on a course that doesn't suit him, and he didn't wear shoe-covers because he had a shoe sponsor. He came 8th the following year in a tougher field, but finished ahead of Adam Hansen. Anyway, he's 6ft5 with huge feet, and what look like very long legs, and rides 175s, which is obviously relatively short for him, yet he has no trouble smashing pretty much anyone around here on flat roads. This has always been in the back of my mind when I scramble to get on his wheel on the local smash-fests.
So, might point.... finally:
Lately I've had a sore knee again, and knowing that 'The Rower' has no trouble delivering power on his "short" cranks, I dusted off a pair of 165s and put them on one bike. They felt a little weird at first, but now I don't even noticed that I'm using short cranks, and I haven't noticed any power drop on my Powertap. So there. Mind you, I don't race in Winter, and I'm just plonking around doing the local flat circuits, so I might change my mind come race season.
