Motor madman Bob Maddox is back with a twin-engine jet bike that makes the raucous rocket he rode last year look tame.

He recently bolted a dual-exhaust pulse jet engine to the side of an ordinary bicycle, donned a leather jacket and helmet and then held on tight as he peeled off a 73-mph run down a deserted back road. And we thought he was crazy when he hit 50 mph on one of his single-engine contraptions last year.

"When you get up to 60 or so, you're thinking 'I really don't want to know how fast it will go,'" he told Wired.com.

Strong words from a guy who used to jump out of planes with a pulse jet strapped to his chest.

Pulse jet technology dates to the beginning of the 20th century when it was developed in Sweden. Germany used pulse jets during World War II to propel its V-1 "buzz bombs." The exceedingly simple internal combustion engines ignite a mixture of air and fuel in "pulses" that occur about 70 times a second. They'll run on just about anything.

Maddox, an artist and cabinetmaker in Medford, Oregon, started playing with pulse jets eight years ago. He built a sweet purple pulse jet cruiser last year for a collector in the Netherlands. His latest creation is beautifully retro-looking machine based on a 2005 Electra cruiser. It weighs 85 pounds and gets its power from a pair of pulse jets.

Why two? Why not?

"This bike has two [engines], although it is really one engine with two tail pipes," Maddox said. "I stacked two 60-pound thrust engines and opened a hole between the combustion chambers and that makes them cycle as one." The new engine also has a push-button starter and throttle.

Did we mention it's loud? Forget your earplugs and you're as good as deaf. A pulse jet at full throttle can pop your eardrums.

"Those Harley guys with the short pipes don't even come close the the noise this thing makes, good or bad."

Despite the lopsided engine placement and the skinny bicycle wheels, Maddox says the ride is pretty smooth. "People wonder if it pulls to one side. It does not," he said. "The wheels have heavy spokes and the tires are aired to 65 pounds with heavy tubes, [so] there is no vibration and I feel real safe buzzing around at 50 or so."

This bike is headed for the Netherlands. Maddox is already working on his next project - a drag bike he estimates will have 1,400 pounds of thrust and "should be the fastest in the world." We'll keep you posted.

Photos: Bob Maddox

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