Take a close look at these two riders' positions. I like the posture of the rider on the left. His position on the bike has been fit quite well. But what I like the most is his hip position. He sits on the saddle with his hips rolled forward as if spilling water out of the front of a bowl made of his pelvis. In contrast, the rider on the right is sitting on his saddle as if it's a bar stool and he's leaning on the bar. His hips are not rolled forward. No water is being spilled from his 'bowl.' This results in a rounded back and unnatural neck and head position. The only way to see where he is going is to lift his head high and curve the neck thus making it more difficult to breathe. It also puts his legs in a position that reduces his potential for power and he has to reach more for the bars.