Imagine this: five engineering students huddle around the prototype of a bicycle drive train. Their professor proudly watches the proceedings. One of the students pushes the pedal and the rest watch in euphoric amazement as the wheels begin to spin.
This is the pay-off of countless all-nighters—a semester’s worth of work. As Lucas Hartman EAS’11 recalls, “The wheels moved! Something as simple as that … We were all just sitting there with the biggest smiles on our faces. Anyone from the outside would have thought we were crazy.”
The timeworn joke is that mechanical engineers are always trying to reinvent the wheel. But one group of Penn engineers has gone a few steps further. They reinvented the bicycle.
Hartman, along with Geoff Johnson EAS’11, Katie Savarise EAS’11, Evan Dvorak EAS’11, and Katie Rohacz EAS’11 W’11 have created what they call the Alpha bike. You’d have a hard time mistaking it for a Schwinn; the Alpha doesn’t have a chain. Instead it has an internal belt drive, completely contained within the bike’s frame. Sensors throughout the bike pump ride data to an LCD screen on the handlebars. But the real advance is something close to the bike-messenger’s holy grail: a switch on the handlebars transforms the Alpha from a fixed-gear configuration to free-wheel.
A fixed-gear bike, or “fixie,” has a single gear and a direct drive train, which means its pedals must always move along with its wheels, and it cannot coast. Fixies have surged in popularity in recent years. Some riders claim that fixies provide extra control, and a better connection to the road. But a single gear makes steep hills challenging, or even dangerous, to climb.
Switching between the two configurations was a mechanical conundrum, and the Alpha team decided to resolve it as part of the Engineering School’s senior design capstone project. Their work won them the school-wide Senior Design championship.
But what earned the bike real street cred was press coverage from Wired, Gizmodo, Engadget, and a slew of other tech publications. “[These are] the blogs we read every day as engineers,” says Savarise. “To see our project featured on those places was cool.”
Even German Playboy reached out to them (though they turned that offer down).
Now that they’ve graduated, the team is looking to patent their work, and maybe turn it into a business.
“What they managed to do with the transmission is really unique,” says their adviser, Jonathan Fiene, a lecturer and director of laboratory programs in the mechanical engineering and applied mechanics department. “They were able to put out a finished product that they had a chance to iterate on, to refine, and to put together—within the scope of their project—in the best way possible. It works, and that’s what’s really, really satisfying.”
From the beginning, the team knew that they would need a lot more financing and hardware than the allotted $1,500 they received as part of their Senior Design course. So they appealed to the corporate world. “I became very good at stalking the CEOs of companies,” Hartman jokes. He called the heads of various companies, and made sure to follow-up by email.
Once one company decided to sponsor the team, several others came on board, allowing the students access to new technologies that would otherwise have been too expensive.
To make the bike’s driveshaft pulley, the team used a new process called laser sintering, in which layers of powdered metal are melted by a laser, gradually building up otherwise impossible-to-make shapes.
“A part like that costs maybe $10,000, and we got it completely for free,” says Savarise.
Penn’s Weiss Tech House donated another $1,000.
But the bike required nearly as much time as it did money.
The team built most of the bike’s components themselves, using the Engineering School’s in-house machine shop. Alpha’s aluminum lug, which weighs about two pounds, was whittled out of a 30-pound brick of metal. That piece alone took a total of 36 man-hours, according to Johnson.
“The amount of time they put into this project I think far exceeds what is expected of a Senior Design team,” says Fiene.
“I love the idea of building things that look like finished projects. And most senior design projects generally aren’t that way,” Johnson says. “Either they’re more research-based, or the final product is kind of hacked together—you know, things are glued and duct-taped. We didn’t want to do that. We wanted to make something that looked like it could be put in a bike store and sold immediately.”
In fact, a local bike shop, Breakaway Bikes, featured Alpha in their store on National Bike to Work Day.
But as of now, the Alpha is only a proof of concept.
The team hopes to innovate on concepts contained within the Alpha. One idea is to build an accessory for ordinary bicycles that would allow their owners to switch between fixie and free-wheel. Their goal is to make a consumer-grade product that is easy and inexpensive to mass-manufacture.
Fiene reckons that the technology that the Alpha team has created could show up in the high-end commuter bike market within the next six years.
In the meantime, the bike is safely locked away in his office—though team members occasionally take it out for a ride. For the most part, Savarise says, “It feels like a regular bike,” but since it has an internal belt drive, it’s a lot quieter. And there’s no chance of your pants snagging in a chain.
“I’m not taking it back and forth to commute,” Fiene says. “I wish I could, but I think it’s a little too valuable for that.”
—Maanhvi Singh C’13