I rode a century awhile back, 24.7 mph. I thought I was going to die. By mid summer, I will ride my 20-30mile rides (very hilly) at about 18-19. Today I ride 17.5-18. It's brutal up and down. I live north of Atlanta in the foothills. If I had flat ground, I feel that 20 would be a happy spot. Also, I am a heavier masher, not tiny climber. I am at my best on slight downhills to flats when I can push a big gear and lay in the drops. It's just when the road turns back up that my compadres teach me a lesson in gravity.