Bicycles

Electronically switchable chainless drivetrain developed for Alpha Bike concept

The Alpha bike prototype features a fully internal chainless drivetrain with electronic switching
The Alpha bike prototype features a fully internal chainless drivetrain with electronic switching
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Installing the LCD display into the 3D printed handlebar
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Installing the LCD display into the 3D printed handlebar
Consturction of the inner pocket to house SWIFT Drive Train
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Consturction of the inner pocket to house SWIFT Drive Train
The front hub contains a drum brake and dynamo, the latter powering the bike's onboard electronics
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The front hub contains a drum brake and dynamo, the latter powering the bike's onboard electronics
First prototype of the SWIFT Drive Train
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First prototype of the SWIFT Drive Train
Close up of the first prototype of the SWIFT Drive Train Transmission
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Close up of the first prototype of the SWIFT Drive Train Transmission
The final version of the SWIFT Drive Train
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The final version of the SWIFT Drive Train
Exploded view of the SWIFT Drive Train system
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Exploded view of the SWIFT Drive Train system
The Alpha Bike features a fully internal chainless drivetrain with electronic gear switching
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The Alpha Bike features a fully internal chainless drivetrain with electronic gear switching
Designing the handlebars for 3D Printing
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Designing the handlebars for 3D Printing
The clutch fittings get a final check
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The clutch fittings get a final check
The chunky bottom bracket containing the SWIFT Drive Train system
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The chunky bottom bracket containing the SWIFT Drive Train system
University of Pennsylvania Mechanical Engineering seniors have developed a prototype bike featuring a fully internal chainless drivetrain with electronic switching
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University of Pennsylvania Mechanical Engineering seniors have developed a prototype bike featuring a fully internal chainless drivetrain with electronic switching
Rear Lugs with 3-Speed Sturmey Archer and Intergrated Shifter Cable
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Rear Lugs with 3-Speed Sturmey Archer and Intergrated Shifter Cable
The Alpha Bike developed by engineering students at the University of Pennsylvania
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The Alpha Bike developed by engineering students at the University of Pennsylvania
The Alpha bike prototype features a fully internal chainless drivetrain with electronic switching
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The Alpha bike prototype features a fully internal chainless drivetrain with electronic switching

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. Oh, and it looks pretty good too...

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 chunky bottom bracket containing the SWIFT Drive Train system
The chunky bottom bracket containing the SWIFT Drive Train system

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.

Installing the LCD display into the 3D printed handlebar
Installing the LCD display into the 3D printed handlebar

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.

Source: Engadget

7 comments
TogetherinParis
The display in the handlebar is welcome as are the hidden brakes. Reliable bicycle systems, more than bolted-together components amid constraints for light weight, should lead designers for other vehicles as well.
Terotech
As a boy I used to ride a neighbour\'s chainless cycle that was then [early 1950s], said to be 40 years old. It used tapered rollers and drove through the backstay tube.
Gregg Eshelman
All that technology yet they designed it for the hunched over, uncomfortable backbreaking position.
flibb
Looks damn fine to me, sleek and sporty and if it works, all the better. the design is not uncomfotable, it\'s efficient!
Alan Braggins
The seat/saddle position only makes sense for a racing bike, and no-one is going to race a belt drive three-speed bike with a dynamo. But it\'s a technology demonstration, not a practical product, and a more sensible design might not have been pictured here.
SAW1967
Spiffy. So if you get a flat, how do you change the rear tire?
Lee Bell
It's not bad for a student project but it has no real-world value. A Sturmey 3 speed hub already has freewheel capability built in and there is no need for freewheeling pedals or operating a clutch by electricity. If you really want or need freewheeling pedals you can get a pedal shaft that uses a freewheel the sprockets are bolted to and it is reliable and simple. It's an interesting idea though and would allow a mid drive assist motor type setup but there are simpler and more reliable ways to do that too.