A Bike Designed by a Committee—the Human Powered Vehicle Challenge

The baking hot parking lot at University of Las Vegas, Nevada’s (UNLV’s) parking lot was carved into a tortuous course to test the limits of multiple teams participating in the ASME Human Powered Vehicle Challenge (HPVC). In addition to a slalom section, strips of wood were laid out to rattle the nuts off your bike. Sharp turns prevented you from building up a head of steam. As contestants found out, the event had little to do with speed. If you had envisioned the sleek, silent fairing clad superlight rolling teardrop shape that would have given you a shot at a world record—a startling 90mph (see below)—you might have brought the wrong bike.

The Utah State University (USU) team was one of several competing at the newly christened E-Fest, an event that wrapped itself around the old HPVC events that ASME holds in the U.S. and abroad. The USU team had studied the rule book and created a vehicle suited for the course. It brought along a partial fairing, but on the day of the event, the team chose not to use it. It had seen others get blown over sideways from crosswinds.

The Design

Figure 1. A winning design. Utah State University's entry in ASME’s HPVC and the team’s only female rider, Katie Henderson, a civil engineering major, won first place in the women's Drag (speed) event.(Image courtesy of Utah State University.)

Racing a recumbent tricycle design that had two wheels in front and electric gear shifters in back was just the ticket for a course that emphasized maneuverability and stability over speed. “Our bike doesn’t fall over,” said Jacob Haslam, a senior at USU. “And it can go faster around turns.

Figure 2. It may not be pretty, but it worked. Triangular gussets added to the stiffness of the carbon fiber frame.

The carbon composite frame was a key ingredient to the success of the USU team. The lightweight material reduced the weight of the frame from 20lb to 8lb. While weight would not be a factor on a flat course that runs in a straight line, the acceleration needed to come out of curves and slow sections gave the lighter frame an obvious advantage at this event.

The flex afforded by the long and wide frame of a recumbent bike also helped absorb shock over the course’s rough patches, negating the need for any active suspension components that would have added weight.

And then there was the heat. In endurance events, the inability of an athlete to shed heat will deteriorate their performance. An all-out effort wrapped up in a plastic shell under the hot Nevada sun could have put students in the hospital with severe dehydration during the 2 ½-hour endurance event as temperatures climbed to near 90 °F. Fortunately, the riders were allowed to take turns.

The vehicle design and construction was paramount. Carbon fiber tubes and lugs were all made by USU students. But that involved going to a neighboring school. “I took a composites course at USU, but it was all theory,” said Haslam. “We studied flat plates with simple loading,” he said. He looks at the team’s race vehicle. It is anything but flat and simple.

Money well spent, I wonder? Haslam, an officer (candidate in the Naval Nuclear Propulsion program) and a gentleman, is not one to respond to a reporter’s dig against his school. However, he admits that coming up short with the practical application of carbon fiber manufacturing methods did force him to use the facilities of a neighboring school.

The Utah team inherited the bike and components from last year’s team, but added and improved the design. The frame was just too flexy before, explained Haslam. As the team’s tallest member (6 ft 3 in) and heaviest rider (220 lb), the frame sagged as much as 2 inches when he was riding it. Adding gussets, orienting the fiber direction of the prepreg, and making other changes lowered the deflection to less than half an inch.

Figure 3. The Utah State team, standing from left: Dylan Ratliff, Eric Lindholm, Katie Henderson, Anson Wing, Brad Thompson, Gabe Ogden, Jacob Haslam, Ryan Coombs, Skyler Wiser, Daniel Noble and Joseph Wardell. On the bike is Daniel Clayton, who is wearing the Utah State cycling team kit.

Results

The USU team came in second overall, when you tallied the scores from the various HPVC categories, which included Drag (speed), and Endurance and Design, with separate competitions for men and women. The team also scored first in women’s Drag and third in women’s Endurance; third in men’s Drag, fourth in men’s Design, and sixth in men’s Innovation.

The Speed Record

Figure 4. Aerovelo’s ETA bike was clocked at 89.59mph. (Image courtesy of Aerovelo.)

In September 2016, a white bullet shape with no visible rider almost broke an incredible 90 mph. Inside the “bicycle” named Eta (the Greek letter often used for efficiency) was Aerovelo Founder Todd Reichart. Todd has a PhD in aerospace engineering from the University of Texas, but he uses his intellectual and physical talents in a more down-to-earth way these days, sitting in the Eta to pedal it to world record for human-powered vehicles at 89.6 pph. According to the Aerovelo website, Reichartis able to expend 1 HP (700 watts) for one minute—a respectable output indeed considering that the winner of the 2015 Tour de France managed 652 watts for a scant 10 seconds. But most of that power is wasted against the wind. Streamlining components like fairings is not allowed in procycling, resulting in an upright bike racer that presents just about the worst shape imaginable to the air stream. Riders try to negate this effect by crouching down.

A Camel Is a Horse Designed by a Committee

The ASME arrived on the scene in 1880, too late to have designed the perfect horse, but not too late to try to make the perfect bike. The professional organization for mechanical engineers, best known for life-saving boiler codes and standards, finds no elegance in the diamond bike frame, the most efficient load carrying structure with wheels theoretically possible. Nor does it marvel at how wind-cheating human-powered bullets like the Eta can blow by a gasoline-powered internal combustion vehicle on the highway. The ASME does not wonder, “How fast can we possibly go?”

But speed is a single criteria that scores with everyone’s imagination. It is pure and easily understood. It is headline grabbing and heart racing. Much less understood is the tortuous course and the pages of finely printed rules that govern a wheeled vehicle that has to do everything under the sun short of climbing stairs. The ASME HPVC event has students leaving dropping off packages in a misguided attempt to make a vehicle with utility, leading to bikes with wire cages of the kind seen in retirement home tricycles. The resulting vehicles lose every chance of looking cool, sexyor elegant. Good luck recruiting members to your HPVC team by showing them the ASME guidelines for what a committee has decided is a perfect bike and which takes a hundred pages to do so. For an event that is betting on the interest of the young, as E-Fest states as it goal, ASME needs to stop trying to produce the perfect vehicle for seniors delivering welcome casseroles to their new neighbors.

Figure 5. Who says engineers don’t have a sense of humor? Hint: It was right after St. Patrick’s Day. The “speed” course contained quite a few curves. The endurance course added distance, curves, rumble strips and more. (Image courtesy of ASME.)