[Evilfrog87]

I was under the impression that bumpers had to start 2.5 inches above the ground. No more, no less.

As to the problem with running over the balls, the Manual says:
“Bumper height has been specified so that robots will make contact bumper-to-bumper and so that the balls will be pushed rather than pulled under the robots.”

The biggest problem I see with the bumpers is going up the ramp. If you use 6” wheels, and have the bumper placed an inch behind them, you cannot make it up the ramp without bottoming out. (that is of course if the bottom of the bumper cannot be higher than 2.5” off the ground)