Electronically switchable chainless drivetrain developed for Alpha Bike concept

The Alpha Bike is an interesting prototype out of the University of Pennsylvania featuring a fully internal chainless drive that can be switched between fixed gear drive and freewheel electronically.

Fabricated entirely in-house, the bike's drivetrain, brake systems and onboard electronics are all concealed inside the custom-machined frame and an LCD display on the handlebars updates the rider on important journey information.

The bottom bracket of the Alpha Bike is home to the Switchable Integrated Free-Fixed Transmission (SWIFT) Drive system designed by University of Pennsylvania Mechanical Engineering seniors Geoff Johnson, Lucas Hartman, Katie Savarise, Evan Dvorak, Katie Rohacz, with Dr. Jonathan Fiene as advisor.

SWIFT uses an electronically-controlled clutch for switching between fixed-gear and freewheeling modes and incorporates a central shaft made from AMS-6514 Maraging steel, a Titanium 6Al4V clutch plate and belt pulleys made from stainless steel.

A front hub houses a drum brake and dynamo which provides power for the electronics, charging two super capacitors which in turn power a suite of sensors and a microcontroller. At the rear there's a compact three-speed planetary gear set actuated by a standard push-pull cable.

The LCD display on the 16 ounce (458 g) 3D-printed handlebars offers the rider useful information such as time, distance, cadence, wheel speed and chosen gears. Bike dynamics information is stored to SD card, which can be examined after completion of a ride.

Sadly, there is no information available on how the performance of the prototype drivetrain compares to more familiar designs. Nor is there any indication that the development might result in a production model.

The purpose of the design project was to "create a bicycle push the boundaries of integrated systems." In that regard, the Alpha team was recently rewarded for its efforts, receiving the Gemmil Award in the University's 2011 Senior Design Competition.

World's first computer; Like Grandad, older than you thought

From Swiss Army knives to iPhones, it seems we just love fancy gadgets with as many different functions as possible. And judging from the ancient Greek Antikythera mechanism, the desire to impress with the latest multipurpose must-have item goes back at least 2000 years.

Clockwork Computer
This mysterious box of tricks was a portable clockwork computer, dating from the first or second century BC. Operated by turning a handle on the side, it modelled the movements of the Sun, Moon and planets through the sky, sported a local calendar, star calendar and Moon-phase display, and could even predict eclipses and track the timing of the Olympic games.

The Origin
One new clue to the origin of the mechanism comes from the Olympiad dial, there are six sets of games named on the dial, five of which have been deciphered so far. Four of them, including the Olympics, were major games known across the Greek world but the fifth, Naa, was much smaller, and would only have been of local interest.

The Naa Games
The Naa games were held in Dodona in northwestern Greece, so Alexander Jones of the Institute for the Study of the Ancient World in New York has suggested that the mechanism must have been made by or for someone from that area.

Older than the Romans
Intriguingly, this could mean the device is even older than at first thought. The inscriptions have been dated to around 100 BC, but according to Jones the device may have been made at latest in the early second century BC, because after that the Romans devastated or took over the Greek colonies in the region, so it's unlikely that people would still have been using the Greek calendar there.

Highlights
The highlight for most audiences, was this breathtaking new animation (Click on the Picture) of the gearing inside the mechanism. It has been made by Mogi Vicentini, an Italian astronomer and computer scientist, and it brings the device to life brilliantly.



Judge for yourself. It shows that the mechanism would hold its own against the best of today's luxury gadgets.