Originally Posted by Tom Bombadil

The total difference between the top of the stroke vs the bottom of the stroke varies by nearly 8/10ths of an inch between 165mm and 175mm cranks. For some, that is going to be a significant difference.

The first time I noticed it was when I took a test ride on a bike and found it quite uncomfortable to pedal. I took note of the crank length and then compared it to my bike (which up to that time, I had never made note of it). I found that mine was 170 and the other bike was 175. Since then I've paid attention to this and have never felt comfortable on a 175. Of course, since I have short legs and should be using a 155 or 160, it goes that I would notice once it got too long.