My wife is very close to your size (actually is 5' 2.5" and has slightly shorter legs, but wears a 5.5 shoe) and she has ridden 170s forever. I put 167.5 cranks on one of her bikes when I set it up, but didn't tell her, and she hasn't ever noticed any difference, so far....
Edit: my wife's pbh is about 30.5" so it depends on what you mean by leg length.
Last edited by 753proguy; 02-13-12 at 03:51 PM.
Reason: Added pbh comment