The guys over at the popular Grind Hard Plumbing Co YouTube channel have made a living out of stuffing massive motorcycle engines into children's plastic Power Wheels. But for their latest garage experiment, they completely abandoned sanity to create what might be the weirdest, most terrifying off-road vehicle on the internet: a side-by-side dirt bike go-kart.The engineering premise was as ridiculous as it was simple. "We bought two identical dirt bikes and glued them together with a go-kart frame in the middle," the team explained. However, getting the contraption to actually drive required a masterclass in custom fabrication.To make the dual-bike setup functional, the team had to completely strip the controls from the individual handlebars and reroute them to a central driver's seat.This required designing a custom five-way brake manifold to operate all four calipers from a single pedal, machining custom cable ends to synchronize dual throttles to a single gas pedal, and routing a single clutch pedal to actuate both gearboxes simultaneously.AdvertisementAdvertisementBecause the two dirt bikes technically operate independently of one another despite being welded to the same frame, the vehicle's handling dynamics are incredibly bizarre. "Sometimes it behaves like something with an open differential, and sometimes it behaves like a locked differential," the team noted. Because you can't stop one rear tire from spinning without stalling its respective engine, it acts as a locked differential—but because the tires can spin at different speeds, it mimics an open one.The Inevitable Crash And A Harsh Lesson in PhysicsWith the mechanicals fully synced, the crew took the "ultimate motocross chariot" out to the dirt track for a test drive. "Well, that's about as terrifying as riding two dirt bikes at once as you'd expect it to be," the driver admitted after throwing the vehicle around the corners.Feeling overly confident, the driver lined the double-bike up for a massive step-up jump, hitting the ramp at the same speed they normally would on a standard motocross bike. The result was a catastrophic nosedive.The vehicle pitched violently forward in the air, ejecting the driver over the handlebars before slamming nose-first into the dirt.AdvertisementAdvertisementMiraculously, the driver walked away with just a sore knee, largely because he perfectly braced for the impact. Reviewing the crash footage in the garage, his co-host noted, "even though you're getting launched face-first into the dirt at mock chicken, you put out your forearm with a closed hand".The vehicle also survived with nothing more than a couple of snapped washers. "I'm kind of surprised that it all stayed together. I don't think I really expected this to be in more pieces," the driver laughed.The spectacular failure ultimately came down to the physics of off-road riding. On a standard dirt bike, riders constantly shift their body weight backward to keep the nose up in the air. "Basically, what it boils down to is you can't shift your body weight around on a dirt bike," the team realized. Strapped into a hard plastic go-kart seat, the driver had no way to counterbalance the heavy front forks, ensuring gravity would always win the battle.
