(Business 2.0) – The Flybar 1200 is an extreme pogo stick that propels thrill seekers more than 5 feet into the air. The stylish bouncer hit stores in November, and online retailer Amazon.com says it had to scramble to meet Christmas demand. There are already thousands of Flybars in use, and skateboard legend Andy Macdonald (far right) has signed on to market the device. Here's how a physicist's string of creative breakthroughs gave rise to the new stick. -- SIRI SCHUBERT

Uphill From Here

In 1997, while pedaling his two daughters to school on a bicycle, MIT-trained physicist Bruce Middleton, then a stay-at-home dad in British Columbia, becomes annoyed by a stop sign at the bottom of a hill. "You lose your momentum," he says. He ponders ways to store a bike's kinetic energy.

His head spinning with images of flywheels and crossbows, Middleton figures out that a steel spring can capture energy during braking and release it later. The drawback? The spring would have to weigh 150 pounds.

Middleton notices slingshots in a hardware store. Back home, he calculates rubber's energy-storing capability to be 10 times greater than steel's. "That was the real breakthrough," he says. Recalling his childhood, he thinks about replacing a pogo stick's springs with rubber.

Middleton rushes to a medical supply store to buy surgical tubing, but it's too bulky. Then, in a thrift store, he sees a pair of moon boots--shoes that are fitted with rubber bands and act like trampolines. Using thick rubber bands and planks from his couch, he builds a pogo-stick prototype and gets 4 feet of air. "The limiting factor was courage rather than mechanics," he recalls.

In 2002, Middleton teams up with SBI Enterprises, the world's oldest pogo-stick maker, based in Ellenville, N.Y. After promoting Flybar at the '04 Gravity Games, giving it free to NBA mascots, and scoring several "best of the year" mentions, SBI gets national distribution by Christmas.