CAMBRIDGE - In the long and colorful history of vending machines, they have dispensed cigarettes and chewing gum, ice cream and lottery tickets, sandwiches and iPods.
But bike helmets?
Enter MIT. Specifically, 12 undergraduates from Mechanical Engineering 2.009, a product-design class renowned on campus and in local engineering circles for creating smart, colorful prototypes from scratch in one semester.
Working with the city of Boston, the MIT students have added another chapter to the annals of the vending machine.
The prototype of the product they call HelmetHub would dispense headgear to what until now have been the mostly helmetless riders of Hubway, the bicycle-sharing system that burst onto the scene in Boston last summer with 60 sleek, modular solar-powered stations and 600 bikes.
Tourists and local residents embraced it, recording more than 140,000 trips in four months. But a city count found that just 30 percent of passing Hubway users wore helmets.
That's a far cry from the 72 percent spotted wearing helmets while riding their own bikes, and it came despite efforts by the city to make helmets cheap and accessible by persuading retailers to carry steeply discounted helmets, sold at or near the $7.50 price that helmet-maker Bell reserves for nonprofits and government.
Much of Hubway's allure is its immediacy, making even that side trip to the store - or the prospect of being saddled with a helmet after returning the bike - inconvenient for some users, said Nicole Freedman, who runs the city's Boston Bikes program, which oversees Hubway.
The HelmetHub prototype features a touch screen similar to those on Hubway rental kiosks, draws power from solar panels, and occupies half the space of a soda machine. And it works, dispensing helmets that adjust to fit most head sizes.
Freedman and the students envision them as sale-and-rental kiosks, allowing those who purchase helmets at the $8 Hubway partner price to return them for a partial refund. They are talking about developing a beta version that could be ready for testing by Hubway riders as early as next summer.
"What the MIT students have done is fantastic,'' said Freedman, who connected with the students after visiting the product-design class's ideas fair in September, where people with interesting problems vie for the attention of student teams.
Along the way, Freedman checked out a cardboard mock-up and on Dec. 1 lent the students a Hubway station, after Boston's bike-sharing system went into hibernation for the winter.
When Freedman saw the finished product two weeks later, she was amazed but not at all surprised, knowing better than to underestimate what a dozen MIT students can do in a few weeks, with little sleep.
In a matter of seconds, she tapped the touch screen, swiped a credit card, and push-pulled a handle with a satisfying th-thunk to withdraw a single helmet.
"That's so great! I love it,'' Freedman said, flanked by students Ignatius Chen and Danielle Hicks, as she tested HelmetHub at an end-of-semester prototype launch that was more Apple-style product debut than class presentation.
The students, clad in finery, presented their projects on stage before a packed Kresge Auditorium. A rock band played, and a spillover crowd watched on monitors in the lobby, where the teams wheeled their creations to a hero's welcome afterward.
Because it was still a prototype, HelmetHub spit out receipts with inspiring messages ("It's a beautiful day for a safe bike ride'') instead of actual charges, and the return slot needed fine-tuning. But it looked street-ready, down to the actual Hubway map on one side and a faux advertisement on the reverse.
Concealed inside, 12 Bell helmets were threaded on a rod and stacked upside down, to keep straps from tangling. A separate compartment awaited returns, to be emptied for cleaning, inspection, and restocking.
The design class, taught since 1995 by Professor David Wallace, is a crash course in product development.
Student teams get dedicated work space at MIT's Pappalardo Lab, an engineer's funhouse equipped with rivet guns and soldering irons, laser cutters and 3D printers. They are limited only by a $6,500 budget and the constraints of the academic calendar.
Each semester has a theme. Last year's was food; results included a sushi-delivering robot and a potato slicer that achieves the elusive, angular tourné cut.
This year's was "on the go,'' so Freedman was a natural invitee to the ideas fair, less than two months after the launch of Hubway.
Among all of the bike-sharing systems around the world, only Melbourne, Australia, has helmet vending machines, posted at two stations. But its carousels are too bulky for Hubway. Boston's stations are designed for a tight footprint, occupying sidewalks, private property, and converted parking spaces.
The MIT HelmetHub is so far the first and only helmet vending machine to be displayed for a North American crowd. The students intend to advance their design well beyond winter break, drawing inspiration from past efforts. (One 2008 class prototype - a lightweight, affordable Braille labelmaker - spawned a postgrad California startup, 6dot, now poised to enter the market.)
The students envision production costs of $2,200 and a sale price of $7,000 per machine. By comparison, a single computerized Hubway station stocked with bikes costs about $50,000 to purchase.
The students in Wallace's class considered the broader business potential for selling helmet kiosks as bike sharing expands; New York City is mapping out a system 10 times the size of Hubway.
"It's great for the environment and communities alike,'' said Jessica Artiles, who helped persuade her teammates to work on the helmet machine, "but I think that needs to go hand in hand with helmets.''
Eric Moskowitz can be reached at email@example.com.