As David Kraus, Ph.D., brings his three-wheeled, human-powered cycle to a stop, it happens again.

“That’s the coolest thing I’ve ever seen,” says UAB sophomore Morgan Reaves, whom Kraus zoomed by just a minute earlier on the Campus Green. “Where can you get one of those?”

Whether it’s in Birmingham or on the streets of San Francisco, Orlando or New York, wherever Kraus rides his StreetStrider, people want to know more about his cycling machine.

Kraus, associate professor in Biology and Environmental Health Sciences, is the inventor of the StreetStrider, a low-joint-impact machine that combines jogging, cycling and skiing into a high-performance sport.

“We have remarkable responses wherever we demonstrate StreetStriders,” Kraus says. “While traveling through Colorado Springs we stopped in the U.S. Olympic training center there. We got four StreetStriders out and went riding around campus. The gymnasts came out of the gym for a ride, as did the volleyball players. Next it was wrestlers, some coaches and then even the tour guides put their tours on hold, asking their audience to wait so they could go for a ride.

“It is a lot of fun to do these sorts of unplanned demonstrations.”

The magic’s in the motion
The secret of the StreetStrider’s benefits comes in the motion of the machine, Kraus says. The cycle duplicates the ideal motion of stationary ellipticals in a mobile device, giving the rider a workout similar to that of a cross-country skier, elevating the heart rate and requiring the rider to use upper body, lower body and core muscles.

“I’ve known for years through my exercise physiology labs I would teach that some of the best aerobically fit people on the globe are Olympic cross-country skiers, and it has to do with that upper and lower body motion working together, like they do when they’re skiing and like you do on an elliptical machine,” Kraus says. “The StreetStrider duplicates that motion of the stationary elliptical machines, giving you a low-impact, yet weight-bearing, full-body exercise that can be repeated day after day. And it adds the excitement and fun of being outside.”

The stable, three-wheel platform makes the StreetStrider easy to learn how to operate. Riders use the arm levers to propel themselves, and when they lean the cycle automatically steers.

“It’s not a very difficult motion for people to learn and to ride,” Kraus says. “We usually give people 15 minutes, maybe a half hour at most, and they’ve got it.”

The idea
Kraus, who came to UAB in 1990, is as an avid cyclist and runner. He often commuted the eight miles from his home to campus on his bicycle, but found that method of exercise harder to do during the cold and wet winter months. He tried stationary bikes and treadmills, but decided elliptical machines were best for maintaining a high heart rate and burning calories with the least impact on his joints and enabling him to repeat a strenuous workout the next day.

On the elliptical machine in the gym someone next to him often would comment how much nicer it would be to have that kind of exercise outside, especially in nice weather.

“Finally, I just thought, ‘Why can’t you use the work done on the elliptical to propel a machine down the road,’” Kraus says. “So I began to draw plans to make a three-wheeled platform with arm and leg levers driving the rear wheel.”

That was more than four years ago. His first intention was to design and build a mobile elliptical for his own use, but as he described the concept to others they began to show enthusiasm for having a similar machine.

“I began thinking that perhaps there would be a market for mobile ellipticals, especially in view of the rapid rise in popularity of stationary ellipticals,” Kraus says.

Spreading the word
Now 10 of the cycles a day are hand-crafted in California, making the production of the machine both expensive and limited. The current cost to purchase a StreetStrider is $1,900, but Ideal Bike, the third-largest bike manufacturer in Taiwan, will begin manufacturing it soon, bringing more bikes to the marketplace and lowering the cost for the consumer.

Kraus says the StreetStrider will be ready for sale in the United States in June. Target.com already has signed a contract to sell the cycle, now in its 13th version, when they are made available. StreetStriders currently are available online at streetstrider.com.

Kraus envisions the StreetStrider’s use for more than exercise. Other designs of the cycle will feature rear baskets, making it useful for students or those who want to make a quick trip to the grocery store.

In fact, Kraus sees the cycle as an alternative to driving.

“It’s the ultimate in green transportation,” he says. “The Segway was a great idea, but we need more human-powered devices, especially in a time when our sedentary lives contribute to obesity.”

‘The Biggest Loser’
The Internet has exposed more people to the StreetStrider, but it still isn’t instantly recognizable.
“It’s not universally known yet so that everyone that would see it would know what it is,” Kraus says.

That could be about to change. Producers from the NBC reality television show “The Biggest Loser” heard about the cycle this past year and wanted to have a demonstration of the machine. Kraus and his associates showcased several prototypes, and the show’s producers were impressed.

“They liked them and then they asked us if we could build them to hold someone who weighed 450 pounds,” he says. “We said ‘Of course,’ so we had to go back to the drawing board and figure how to do that.”Kraus and his designers developed a new reinforced frame using aircraft steel alloy tubing to create a cycle to meet the weight demands of the show’s producers. They delivered a fleet of StreetStriders to “The Biggest Loser” campus in Calabasas, Calif., this past fall and returned in January to train this season’s contestants. The contestants now are using the StreetStrider as part of their regular exercise routine, and there is hope that they will appear on television during this season.

There is little doubt that the StreetStriders are helping the contestants. Testing showed they would burn 12 to 13 calories a minute on a traditional, stationary elliptical machine. But when they rode the StreetStrider, they burned 17 calories a minute and up to 430 calories every half hour.

“The contestants took to them quite avidly,” Kraus says. “They began to compete on them, see who could get them up on two wheels. They were rather vigorous.

“It’s a reality show and we’re not guaranteed the StreetStrider will appear this season,” Kraus added, “but they certainly have footage of the contestants having fun while riding. Hopefully it will air.”