A bicycle built for none

Perhaps one of the biggest challenges in bringing any new product to market is testing. For Joe Lane, the developer of a new transmission system for bicycles, this task was made easier thanks to the students at Bucknell University (Lewisberg, PA). At the request of the Bucknell Small Business Development Center, the mechanical engineering senior design class designed and built a robotic testing rig to determine the viability of Lane's gearing system. Like the traditional sprocket and derailleur, Lane's design uses a chain. But instead of the chain moving from sprocket to sprocket, gears are shifted by circular arrays of small plastic pins that retract and extend as different gears are selected. To test Lane's prototype, the students programmed the test rig to move the gearing system through each of the 24 gears in a sequence that mimics the shifting choices made by a human rider. The test device also gathers and stores data on the accuracy of the shifts and the system's durability, says Steve Shooter, the student's professor. The bike's pedals are connected to a one-horsepower motor that imitates the cranking of a rider. The rear wheel drives a drum that is connected to another motor that provides resistance to simulate varied terrain. After the rig was built, the students tested the common sprocket derailleur transmission and Lane's new design. They found the new design reliable and efficient. In addition, the new gearing system allows a rider to shift while pedaling up a steep hill or when not pedaling at all-moves that are difficult with a traditional derailleur. Lane also eliminated "cross-chaining," a situation where certain gears bend the chain at varying angles, putting additional stress on the chain. "The design, fabrication, and programming of the test rig was an incredible feat for a group of undergraduate students," says Shooter. "They did a fantastic job." For more information about the test rig, contact Shooter at [email protected]. For more information about the new gearing system, contact Lane at [email protected].