Turning bicycles into an engineering study tool

They say you never forget how to ride a bike.

Dustyn Roberts hopes that her students never forget how a bike—something everyone has either seen or ridden—is the ideal introduction to engineering concepts like materials, urban design, and stability.

Instead of examining something more intimidating or imposing—say, jet engines—“I can bring a bike into class and we can talk about mechanical advantage and then ride up a hill,” says Roberts, a practice associate professor of mechanical engineering and applied mechanics in the School of Engineering and Applied Science.

With bicycles at the center, she created a Penn Global Seminar, Bicycles: The Mechanical Advantage, which aims to impart engineering skills as well as offer practical experience in bicycle design and maintenance.

The class also tackles the human side of cycling, including transportation policy. This semester, a guest speaker from Philadelphia’s Office of Transportation and Infrastructure Systems discussed traffic measurement and intersection design.

Requirements: Physics and bike know-how

It’s a consistently popular class, with 63 applications for 22 spots this year. Students taking the class have spanned the gamut of majors, including cognitive science, architecture, biology, political science and computer science. The only restrictions are that they must have taken physics and know how to ride a bicycle. “We had students that have biked across Europe, biked across different states in the U.S., folks who have been bike racers, who have worked in bike shops,” says Roberts.

Max Huang, a second-year physics and chemical engineering major in the Vagelos Integrated Program in Energy Research, says he was drawn to the course by the combination of hands-on mechanical experience and study of how bicycles are used in the world. “It seemed like such a fascinating way to integrate engineering principles into seeing how they applied to society,” he says.

The spring break travel experience to the Netherlands—the No. 1 cycling country in the world, with 17 million people and 22.8 million bikes—was a focal point for many students.

They learned that in the 1970s, Dutch society was as car-reliant as the United States, but began slowly implementing policy and infrastructure changes that led to increased bicycle adoption, says Huang, who is from Montreal.

Exploring Dutch cycling culture

“They have underground bicycle parking lots near every major train station that can house up to thousands of bicycles,” says Huang, rattling off design features that the group saw on their rides around Amsterdam: paved cycling paths painted red, intersections with long lead-ups to improve cyclist visibility, and cobblestoned car paths to force slower driving.

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“As soon as you get dropped off in the center city, you just see bicycles whizzing by you. It’s a little scary to cross the streets—you realize they don’t slow down for you, they expect you to just get out of their way,” Huang says. “But Dutch cycling infrastructure is very intuitive. In a matter of 1-2 days cycling around for half an hour we all got the hang of it and knew how to navigate it.”

Roberts had traveled to the Netherlands three times prior and says her favorite part of the course was watching the students experience the cycling culture for the first time. “The vast majority of them had never been to Europe, let alone the Netherlands, but they’ve all been biking,” she says.

The group spent five days in Amsterdam and two days in Delft, seeing how the Netherlands supports cyclists with dedicated lanes and intentional bike-friendly design. They also visited a technical university for a life cycle assessment workshop, learning about the environmental impact of manufacturing bicycles, as well as a look at experiments on steering and cargo carrying. And their time included some fun, with a bicycle scavenger hunt, tours, and museum visits.

Joy + engineering

“The joy on their faces was just amazing; they were visibly excited when they got back, and super annoyed that we don’t have the opportunity to feel that kind of joy every day,” Roberts says. “It feels like this surreal alternative universe. There’s no reason we can’t do that in Philadelphia or the U.S. in general.”

At Penn, students spend time on the fundamentals of bicycle use and design, such as forces and mechanics. They examine bicycles and how they maintain stability. (For example, Roberts says: “You can’t turn right on a bike without first turning left a little bit.”)

One subject the class has tackled is the question of frame design, from the quasi-ridiculous—“Can we make it out of cheese? Can we make it out of bamboo?”—to the more technical, such as determining forces of loading. “It’s a helpful tool to teach different types of engineering and how they intersect with the world around you,” Roberts says.

A final project takes up the last month of the course, which could cover fabrication, design, research, or a simulation. “They get to explore their interests within the umbrella of a larger bicycling and engineering world,” Roberts says. “Some of the projects are more research-focused—redesigning Philadelphia from a bicycle perspective—while some are very fabrication-focused.

“For example, when we were in the Netherlands, you’re not allowed to hold your phone out while cycling. One idea students pitched was a vibrating or blinking handlebar with actuators or sensors, so instead of looking at your phone, you would feel the vibrating and it would tell you to turn left,” she says.

Huang’s project is focusing on carbon emissions at different stages—manufacturing, shipping, use, and end-of-life—and offsets from not using other modes of transportation.

‘Bikes can change the world’

Why are bicycles so important, and why devote such intense study to them? “I think bikes can change the world,” Roberts says, her voice full of enthusiasm. “Maybe it sounds hyperbolic or cheesy, but when you ride a bike you get exercise, you’re exposed to fresh air, you use the city around you, you can stop and chat with neighbors more readily—it enables a social fabric that cars don’t.”

The U.S.’s car-centric mindset has been well documented, as have the health, social and environmental benefits of cycling, Roberts says. “When you look at happiness in different countries, when you look at how many people ride bikes, there’s a pretty strong correlation of how those line up,” she says.

Bicycles also enable people to get an apartment or house closer to where they work “and create a lifestyle that is intentionally more earth-friendly, more health-friendly, more environmentally friendly, and better for your wallet,” Roberts says.