One thing which increased my acceleration and sprinting speed was to gain few extra pounds of lean body mass and increase my strength through weight training...I am not really all that fast compared to some other cyclists...I spin out at 29.8 miles MPH on my fixed gear with 69 gear inches on flat roads with no wind and can only maintain that speed for under 1 minute....The only way for me to go faster would be to start using a geared bike , which is something I don't want to do , because I just enjoy riding fixed.