Perpendicular to the axis of the drum. You'll need as many layers as it takes to make the "bumps" noticeable. For watching tv, I needed 4 layers; less than that wasn't obvious enough when part of my attention was on the tele. Depending on how wide a "shoulder" you want, you can lay tape on the last 1" of each side of the front roller up to maybe 3" on each side (more than that, and your "road" is too narrow). The tape shouldn't go all the way around the circumference of the roller because you want the bump-bump-bump sensation when you're riding on and off the tape. I used strips ~4" long.