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AIM FULL BODY BIKE

 

The AIM Full-Body-Bike solves the problem of how to build a normal-sized, 26-27 inch two-wheeled bicycle that riders can pedal with their feet alone, their hands alone, or with their feet and hands simultaneously, thus providing both an upper body and lower body workout at the same time.

Existing Hand-Powered Bicycles

A number of hand-powered bicycles have been developed. Some are not really bicycles, but adult tricycles primarily for physically impaired riders who have limited use of their legs and feet. (http://www.ushf.org/)

Two-wheeled hand-powered bicycles have also been developed. They tend to be low, recumbent bicycles with additional small side wheels that prevent physically impaired riders from falling over if they lose control.

In both of the above cases foot pedaling is not an option.

A few hand and foot powered bicycles have also been built. One model is called a "rowbike,' and is also a low-center of gravity bicycle that involves a rowing, as opposed to pedaling, motion. The length of such bicycles is often quite a bit greater than that of standard two-wheeled bicycles. (http://www.aviroute rowingbike.com/rowingbike/manoeuvrability/)

How the AIM Full-Body Bike Was Developed

With the above history in mind, AIM set about the task of creating a hand and foot-pedaled bicycle of standard size and shape. As far as we are aware no such bicycle existed prior to our efforts.

The initial task was presented to a team of Stanford University senior undergraduate mechanical engineering students taking the course, ME 113 Mechanical Engineering Design taught by Professor Fritz Prinz in the Spring quarter, 2003. The students were told that they could not change anything to the rear of the handlebar neck of a normal bicycle, i.e., all changes had to take place from the neck forward. The students were given a budget of about $1,500 and ten weeks to develop a fully functional working bicycle.

Instructor: Professor Fritz Prinz
Project Coordinator: Richard Reis
Project Coach: Uri Geva
Student Design Team: Sean Whalen, Caitlin Kalinowski, K.C. Lukens, and Carlos Jorge
Other Advisors: Doug Schwandt, Jake Workman, Vit Bares, Alan Ross

 

VERSION #1

The student team purchased, at a considerable discount, a Cannondale Lefty DLR bicycle and made several modifications to it. A unique feature of this Cannondale model is its "Lefty" fork that goes down only one side of the wheel. This arrangement allowed the students to put a sprocket on the other side of the front wheel over which they could run a chain that was also connected to a sprocket system mounted off the handlebars that in turn was linked to a crank and hand-pedal system that the rider could use. Another interesting feature of this initial version was the placing of the cranks in a parallel position, as opposed to the 180 offsets found in standard bicycle foot cranks.


Version 1

Photo 1

This arrangement was necessary to enable riders to better steer the bicycle while pedaling with their hands. The student effort was a significant achievement and served to prove that such a bicycle could be built and ridden. (The students received an "A" grade in the course.)

Version #1 did have some problems that needed to be corrected in order to make it safe to ride long distances. The fork was placed on the right side of the wheel instead of the left side for which it was designed and this allowed the bolt that held the wheel in place to turn in the wrong (loosening) direction. The bicycle also had the front brake removed which not only reduced the overall braking power of the bicycle, it eliminated the back-up safety feature designed to hold the wheel in place should the front axle bolt fail for some reason.

VERSION #2

To correct these problems, Mr. Jake Workkman of the Wheel-Away Bicycles in Campbell, California (http://www.wheelaway.com/) was asked to make various modifications. Among other things the fork was returned to the left side of the wheel, a front hand brake was added and a shock absorber was added to counteract the air spring in the Lefty fork. See Photo below

Photo 2

VERSION #3

Richard Reis, AIM executive director, rode Version #2 to and from Los Altos, California to Stanford University (about 12 miles round trip) most week days during the months of August - December, 2003 making minor modifications from time to time.

Good as Versions #1 and #2 were, they did not fully meet the goal of a "normal" bicycle that could be pedaled with the hands and the feet. The Cannondale was an expensive bicycle with a unique front fork arrangement not likely to be something a normal rider would want to acquire. In addition, the front end of the bicycle was quite heavy and this made steering somewhat difficult. (Note: The full bike weighed 75 pounds compared to a typical bicycle weight of 20-25 pounds.)

Photo 3

In January, 2004 Reis set about building on the Version #2 concept by modifying a standard, Specialized 26 inch 02 Crossroads Comfort Bike that was purchased from the Stanford Bike Shop for $200.00 After developing a number of prototypes and riding them to and from work, Reis settled on the one shown in Photo above. The special features of this bicycle are listed below:

1.) The standard front wheel is replaced by a standard rear wheel with a single sprocket.

2.) In order to accommodate the wider rear axle, the front fork has been widened by bolting the lower pieces of another fork on the sides of the cut off portions of the original fork.

3.) The rear triangular portion of the frame of another similar bicycle was cut from that bicycle and mounted on the Version #3 bicycle as shown. By using standard handlebar mounting gear obtained at Wheel Away the triangle was rotated 180 and attached above the standard Specialized handlebars as shown.

4.) A standard rear hub and sprocket was placed in the standard rear bracket of the triangular fork, which now extended over the front of the bicycle above the sprocket on the front wheel.

5.) A second, smaller sprocket taken from a standard derailleur, was mounted along the triangle support just to the back of the rear hub on the triangular frame. (Again see photo). A lengthened chain was then run from the main pedal sprocket to the front "rear" axle down to the front wheel sprocket; back up over the derailleur sprocket and back to the main pedal sprocket.

6.) An important feature of the above arrangement is the ability to adjust the position along the frame of the derailleur sprocket so as to provide the chain with the proper tension.

7.) The pedals of the original parallel cranks were removed and replaced with the cylinder grips as shown. A third brake, behind the front fork was added and the grip was attached to the front left hand pedal.

With the above arrangement it is possible to ride the bicycle in the normal way with the gearshifts and standard front and rear break grips on the standard handlebars. At any time riders can remove their hands from the standard handlebars and grip the hand pedals. They can hand coast in this position or hand pedal, whichever they choose. Braking is done with the left grip while in the hand pedal mode. Shifting and standard braking is done by returning the hands to the standard handlebars.

VERSION #4

While Version #3 worked well it still had some problems. The rotating hand brake on the left hand pedal was awkward and still required letting go of the right hand pedal in order to use the rear brake.

Version #4 solves these and a number of other minor problems. It was constructed by Reis from two new 26 inch Townie Electra bicycles as shown in Photo #4.

Version 4

Photo 4

 

The Townie bicycle has a number of desirable features:

  1. The foot pedals are to the front of the seat post so a riders can sit on the seat while their feet touch the ground when   stationary. This adds safety and stability.
  2. The bike has a three-speed internal rear hub which means that there is no need for a derailler to change the length of the chain while shifting.
  3. The bike has a coaster rear brake allowing the rider to brake the rear wheel by pushing backward on the pedals

The rear wheel of Bike #1 replaced the front wheel of Bike #2, which became the final bike.

Version 5

Photo 5

Making this change required the spreading the front fork of Bike #2 by about 0.75 inches. The coaster brake of this now front wheel was attached to the fork and the gear-shift for the front hub was mounted on the left handlebar. The rear triangular frame of Bike #1 was cut and mounted on the handlebars of Bike #2 in a manner similar to that of Version #3. The hand-pedals were aligned in the same way as were the guide sprockets.

This arrangement allowed riders to brake with both their feet and hands without removing either from their rotating positions. Simply by pushing forward on the hand-pedals when in their lower position riders can easily slow down the front wheel while maintaining full control of the steering.
Not only can riders shift the rear wheel to one of three gears, they can do the same with the front hand pedaled wheel giving even more control while pedaling and steering.

Bike 10/6

Photo 6

VERSION #5
One difficulty with Version #4 was that the triangle frame piece attached to the handlebars extended much too far in front of the bike making it hard to control when turning. The length of this unit was dictated by the fact that it was cut from the rear of Bike #1 and was never designed to extend out in front of the new bike. A significant portion of the frame was cut off and the pulleys were mounted closer to the handlebars. (See Photo #6). Note that the pulleys could not be brought too close the handlebars otherwise the chain wouldn't clear the front fork and a rider would not be able to make a sharp right turn.

Also note the cool windshield, the red lights on the valve stems and the Sissy Bar. Now all we need are the plastic streamers that extend out from the handlebar grips.

 

VERSION #6

A problem with Versions 1-5 is that the hand crank support tube is mounted off-axis in front of the neck of the fork. A more ideal position would be an extension along the neck axis itself and this is the case in Version #6. (See Photos #7 and #8). Not only does this arrangement provide a cleaner look, it is lighter due to the absence of mounting gear, while providing a more natural and balanced steering system.

Photo 7

Photo 7

Photo 8

Photo 8

In Version #6 the rear toolbox has been replaced by a Zuca Bag ( http://www.zuca.com/) that can be easily detached from the carrier for transport.

VERSION #7

In Version #7 a decision was made to return to the two-chain option. In this approach each chain is shorter and as such has a smaller vibration amplitude and is thus more stable with respoect to the chain sprockets.

Photo 9

Photo 10

VERSION #8

Version #8 is an entirely new bicycle, but one clearly modeled on the previous version.  In Version #7 a number of "mistake" holes had been drilled in the frame (and covered with black tape) and this made me nervous.  The hub at the front support was taken directly from the rear of a discarded 12- speed bicycle and had many more sprockets - and weight - than needed. I also thought it was time to "clean up" the design and bit, to make it look less cut-and-paste and more like something that would come out of the same factory that made the original Townies.

I started with two identical three-speed Townie Electra's, just as in Version #7, except that the new ones were red.  See photo below.



Photo 11

I replaced the front wheel of the first (final) bike with the rear wheel of the second bike and started cutting up the second frame as
before. See photo #12 below.

Photo 12

I decided to use the entire rear triangular frame of the first bike just as in Version #4.  This guaranteed that the hand pedaled sprocket
would line up exactly with one of the sprockets in the front hub.  It also provided a factory -designed support for the front hub. Because, unlike Version # 4, the mounting took place on top of the neck, the extension out over the front wheel was not as great.

Photo 13

This new arrangement  did create an undesirably high moment of inertia when steering.  This was reduced considerably by mounting the heavy bicycle light battery to the rear of the stem axis, providing a counterweight that makes steering quite easy.  Since the overall
weight of the bicycle remained the same there was no real downside to such a move.

I replaced the full sprocket front hub with one that allows one or more sprockets to be replaced by spacers.  Thus, I only had to use two sprockets.

Photo 14

A number of other touches went into giving the bike a more polished look.  I replaced the toy Honda rev-and-roar motor with a custom
Townie bag from Electra.  I purchased a backrest designed for children's bikes and mounted it in front of the Zuca bag from Version
#7.  It is much more comfortable.  Finally, I ordered Fullbodybicycle.com signs for mounting on the sides of the Zuca bag.

Photo 15

For comments and further information contact Richard Reis (reis@stanford.edu)