Alpha Bike-internal chainless drive switches fixed gear & FW

[MitchJi]

Hi,

...The Alpha Bike, a chainless drive creation from a team of mechanical engineering seniors at the University of Pennsylvania.

Built in-house by the engineering team, the Alpha Bike features an internal chainless drive that can be switched between fixed gear drive and freewheel electronically. The bike’s drive-train, brake systems and onboard electronics are hidden inside a custom-machined frame. An LCD display on the handlebars updates the rider on important journey information. An interesting photo slide show is available on the designer website...

Source: Clean Technica (http://s.tt/12D5w)

http://www.thealphabike.com/ALPHA/ALPHA.html
http://www.thealphabike.com/ALPHA/SWIFT_Drive_System.html

Alpha's bottom bracket houses the bike's SWIFT Drive Technology. The Switchable Integrated Free-Fixed Transmission uses an electromechanical actuated clutch to switch the bike's configuration between fixed-gear and free-wheeling modes. Metallurgical considerations played a major role in selecting materials for all of the transmission components. The strength and weight of Titanium 6Al4V made it the material of choice for the clutch plate, while AMS-6514 Maraging steel was used for the central shaft due to its extreme harden-ability (56 HRC). Bronze was used for its self-lubricating proper- ties at the core of the clutch, while 6061-T6 Aluminum was used for lower-stress components. The geometrically complex belt pulleys were made from Stainless Steel using Direct Metal Laser Sintering, a process which allowed us to create otherwise un-machinable parts. The rear hub incorporates a compact three-speed planetary gear set actuated by a standard push-pull cable. Finally, as shown in the picture on the right, the belt is easily accessible by removing the bottom bracket plate, making maintenance of the belt simple.

http://www.thealphabike.com/ALPHA/Frame.html

The frame geometry, based on industry standards for urban cycling, en- sures full integration of all mechanical and electrical components.It is constructed from carbon fiber tubes epoxied to aluminum lugs that were manufactured in-house using CAD, CAM, and CNC machining. Hysol-9430 epoxy was used for its strength and ability to bond aluminum and carbon fiber, it is commonly used in race car applications. The frame was assembled using a custom jig and cured for 5 days before final assembly could take place.

http://www.thealphabike.com/ALPHA/Electronics.html

The front hub houses a drum brake and a dynamo which generates power for the onboard electronics. Rotation of the front wheel illuminates the integrated rear LEDs and charges two 120 Farad super capacitors. These capacitors power a suite of sensors and an M1 microcontroller.This system includes a 6-DOF inertial-measurement unit, a clutch sensor, and two hall effect sensors, which provide cadence and wheel speed. An LCD screen shows useful real-time data to the rider. Additional data, which can be used to analyze bike dynamics post-ride, is stored on an SD card that is easily accessible from beneath the handlebars

http://www.thealphabike.com/ALPHA/Handlebars.html

The handlebars were designed for ergonomics as well as the internal routing of cables, wiring and mounting of a printed-circuit board and LCD screen. We made use of 3D printing to prototype sections and create the final handlebars. The resulting ABS assembly was laid up with preimpregnated carbon fiber for strength, while keeping the plastic core intact for routing and electronics purposes. The weight of the handlebars is 458 grams, lightweight for the bicycle industry.

 

[MitchJi]

Hi,

Its a belt drive inside the the chain stays:
http://www.thealphabike.com/ALPHA/Media.html

 

[Miles]

http://endless-sphere.com/forums/viewtopic.php?p=405279#p405279
I think your presentation might generate more interest than mine did, Mitch


I first saw this, here:
http://www.bikerumor.com/2011/05/02/the-alpha-bike-an-electronically-controlled-fixedfree-concept-bike/

 

[richmpdx]

Wow, elegant although production would presumably result in a very costly bike. In the end I wonder what the efficiency of the drive is for transmitting power to the rear wheel versus a conventional chain or gates belt drive.

Rich