Ironically, my average speed seems to suffer when I push myself too hard. My commute is 15 miles each way which is a relatively short ride for me. When I push it hard, I tend to burn out and my average speed suffers later in the ride. Today I started out a bit earlier, so I was definitely in no hurry and took it easier than usual. It was too dark to see my bike computer. After 10 miles the sun came up. I looked down to see my average speed was 19.4 Mph which is way faster than normal.