Speed Bumps

What causes people who drive vehicles designed to speed across the roadless African landscape at 70 miles per hour, rattling over creek beds and termite mounds, to slow down to idle speed or slower to go over a speed bump?

They drive like they have an aquarium full of piranhas in the front seat. Or a tray of champagne flutes filled to the brim.

A speed bump should feel like a bump. If you can feel a gradual assent followed by a gradual descent, repeated 30 seconds later by the rear set of wheels, you're going too freaking slow. Get out of my way.