Basically you don't know if you don't try. The wife is short at 5' 3-1/2". She had always been on 170s and never thought about it. Got her 165 and she did not notice a thing. Got her some real shorties as an experiment and to deal with a toe clearance issue. 150mm. She did a 30 second test ride and came back said we needed little cranks on her other bike too. Then she disappeared for an hour or so and confirmed she wanted shorter all around. Hills that were walking hills for her are now ridden and ridden in higher gears. She doesn't need tiny gears any longer. No way we would have known this if the experiment were not made.