There is absolutely no performance (read increased power or speed) advantage and anybody who tells you there is is misinformed. They actually have some studies and there is zero difference. Now there may be comfort reasons or an advantage because they do keep your feet on the pedal and you wont slip. The rest is in peoples heads. If you buy them, buy them for comfort but don't buy them dreaming they'll turn you into Lance. In my experience they not worth it and they were hard on my knees. I actually like being able to move my foot to different spots on the pedal.