How can two vehicles be so inherently similar yet so entirely different? It’s hard to figure. But the Triumph Rocket III Roadster and the Yamaha Star VMax are exactly that. On one hand, they’re both big, long, unfaired, ultra-heavy, über-powerful asphalt shredders. On the other hand, one’s a north-south inline-Triple, the other an east-west V-Four. The lighter one with the smaller engine is priced just $500 short of 20 Grand, while the bigger one with the monster motor is only a buck shy of $14,000. One looks like an exercise in old-school motorcycle design, the other like a prop from a Transformer movie.Still, they invite comparison, because there’s nothing else like them on the road. They’re not cruisers, tourers, sport-tourers or sportbikes. They’re two big, badass hot-rods, each boasting its own way of doing the same job: pulling your arms out of their sockets while pushing your eyeballs farther into theirs.