OK guys bear with me here, I'm still a rookie! I bought a Proform practice tree to practice my reaction time. IT has a setting for roll out and bump time. I have found that if I set the roll at .030 my reaction times are good. Double 0's and high teens. Which if I understand correctly that means I need to roll into the staging lanes a little farther. I have only been rolling in till the stage light light's. Now what is the bump for? Thanks guys.