You might fall in love with the chrome and curves, but some bikes turn into vibrating, oil-leaking disasters before you even finish your first summer ride—like the Norton Commando 961, a $20,000 “classic” that’s riddled with warped brakes, failing engines, and parts that are nearly impossible to find. And just when you think it can’t get worse, the Ducati 996 lures you in with world-champion styling only to punish your back, wrists, and wallet every time you fire it up—let’s watch the video to see which other motorcycles made the list of ultimate regrets...