The document provides details of a design project to develop a new product called the Omnibike for Rhoadescar International. The Omnibike is intended to be a fitness bike that incorporates carbon fiber, allows for upper body exercise, and can fold or disassemble to fit in a sedan. The document discusses the competition, various design considerations including materials selection between carbon fiber and aluminum, methods for incorporating carbon fiber construction, the final frame and powertrain designs, and major contributions from team members.

1. Design Review
Lloyd Ambrose
Willie Carter
Andrew Marione
bike
Allan Regis
Daniel Tepper
Chufei Yu
(High-fidelity prototype)

2. Rhoadescar International
• Leading International Quadricycle
Manufacturer
• Headquarters: Hendersonville, TN
• Founded: 1991
• Key people
– David Rhoades (Founder, President 1992 –
2009)
– Bill Pomakoy (Co-owner, President, and CEO)
– Phyllis Shelton (Co-owner)

3. Design Project Description
• Develop new product called “The
Omnibike.”
• Fitness bike based on “GoBoy:
Comfort Ride”
• Key Design Criteria:
– Incorporate carbon fiber into design
– Add an upper body exercise to
augment fitness benefits
– Design such that product can be
folded or disassembled to fit in the
back of an average sedan
– “Mom Certified”; an older woman
should be able to intuitively
understand what our product is, and
how it works

4. Needs Wants
• Exciting aesthetic quality
• Intuitive, no lean steering
system
• Multi-gear drive train
• Lightweight design
• Simple repair and
replacement
• 4 Wheels
• Carbon Fiber
• Upper-Body Workout
• Fold/Disassemble
• 20” wide comfort seat
• Capable of seating 300lb
riders

5. The Competition
• No product exactly like the Omnibike exists
• Individual design elements are used in design of
Quadricycles, Tricycles, Bicycles, and other vehicles.
• Focus Elements:
– Frame Design and Material Selection (Carbon Fiber)
– Upper Body Movement
– Folding/Disassembly

6. The Competition—Frame Design
Pacific 2rider
Very-Eco Quadricycle
Specialized Big Hit
Custom Bicycle by Svetlyo Kostov
Da Vinci Tandem Bicycle

7. Folding
• Not Quadricycles, but
Bicycles.
• Two main styles of folding:
– Fold in half at center
hinge
– Slide through sockets into
a single plane
• Goal is to get bike to a
compact shape in a single
plane
Pacific Cycles
If
Pacific Cycles
Carry Me

8. The Competition—Upper Body Exercise
• Seen in exercise bicycles and more commonly in tricycles for
handicapped athletes.
• Wheel with handles rotates chain that drives either front or rear
wheel.
Varibike
Pacific Cycles Handy

9. • High Modulus of Elasticity
• High electrical and thermal
conductivity
• Low coef. of thermal expansion
• Low failure strain
• High Strength
• Low Density
• Anisotropic
Carbon Fiber Properties

10. General Comparison
Taken from “Aluminum: Properties and Physical Metallurgy”, John Hatch and “Carbon Fiber Composites”, Deborah Chung
Aluminum:
Density: 2600 kg/m3
Modulus of Elasticity: 62 GPa
Poisson’s Ratio: 0.33
Ultimate Tensile Strength: 115 MPa
Carbon Fiber:
Density: 1600 kg/m3
Modulus of Elasticity: 70 GPa
Poisson’s Ratio: 0.1
Ultimate Tensile Strength: 600 MPa
Steel:
Density: 7850 kg/m3
Modulus of Elasticity: 190 GPa
Poissons Ratio: .27
Ultimate Tensile Strength: 276 MPa

11. - PAN - most common,
less expensive
- 610K TOW PITCH donated
by Oak Ridge Nat’l Labs,
fiber strands
Future Challenges: moving
from fiber to prepreg
610K TOW is hard to mold
PAN (polyacrylonitrile) vs PITCH (petroleum pitch)

12. The experimental 610K TOW carbon fiber is exactly
that—experimental. How can a group of
undergraduate college students think of a way to
use unimpregnanted carbon fiber to build a sturdy,
four-wheeled bicycle??
Our Problem

13. The bladder and mold method
• Carbon fiber sheets are placed over an inflatable latex ‘bladder’,
which is inflated in high pressure mold
• Disadvantage: Requres carbon fiber to be pre-prepared in
uniform sheets, + expensive tooling and resources
Possible Methods of Carbon Fiber
Manufacturing

14. The ‘plug and bag’ method
1. Create a plug out of Styrofoam
2. Wrap the plug with carbon fiber and epoxy (prepared in sheets or otherwise)
3. Vacuum-bag to create a more compressed carbon fiber structure
4. Melt the Styrofoam with acetone once carbon fiber is dry
Disadvantages: Carbon fiber tubes would be incredibly ununiform in strength… failure
could result in catastrophic injury for the end user

15. Manufacturing Option 3—The Uhing
With the help of my peers and the CEO of a bicycle manufacturing company known as Slipstream Bicycle, LLC,
we considered constructing a uhing apparatus, which uses small devices called uhings that move up and down
a shaft at a constant rate as it rotates. By threading carbon fiber strands through a plate mounted on top of a
uhing as is goes up and down the shaft, we can wrap a plastic mold with the carbon fiber at an angle, and in a
uniform manner.
Carbon
Fiber
Spools
Uhing
Devices
Plastic
Mold
Small
GearmotorsRubber Belt Oak Ridge National Laboratory has offered to
allow our team to utilize their state of the art
3D printers to print plastic molds of our pieces.
Once the components are wrapped with carbon
fiber, they will be sent back to Oak Ridge and
baked in an over to cure the impregnated
carbon fiber and melt out the plastic mold.
Finally, the parts will be sent to Rhoadescar’s
mill to be cut in the appropriate shapes and
dimensions.

16. However…
In the end, the team decided that purchasing
prefabricated carbon fiber tubes was the wisest
decision. We decided that it would not have been
ethical for us to design a device not knowing if it was
safe to ride or not, and that trying to ‘reinvent the
wheel’ would have taken too much time away from our
core objectives. Ultimately this proved to be a very
wise decision for us.

17. Omnibike Initial Concept Design
… my initial design was WAY too
unbelievable. We all quickly
realized the constraints of modern
manufacturing

18. Final Frame Design
Final CAD dimensions done by Daniel
Tepper, once we knew what parts we
had, and what their dimensions were

19. Dissasembly
The tubes of the bicycle
would interlock and be kept
in place via store-bought
push pins. When the bike is
to be disassembled, the
pins would be removed, the
tubes would slide in (to
allow for easy removal of
chains), and then the tubes
can easily be slid out.

20. Powertrain Considerations
How might we achieve gear switching with rear-wheel drive,
while still allowing the bicycle to disassemble??
My proposed solution was a jack-axle setup, in
which the cassette of the bicycle sits on the back
wheels. The jack axle’s main job would be to allow
the chain (or carbon belt) to be easily removed for
disassembly, then easily put back onto the bike to
ride again.
A more advanced version of our bike could make use
of a second cassette, which would provide a much
larger range of gear ratios for the bicycle.
(Powertrain notes included separate in portfolio)
Cassette
(In Use)
Cassette
(Not In Use;
no derailleur
on bike)
Overrunning
Clutch Gear

21. Power Train Plans
What is an overrunning
clutch?
http://www.youtube.com/watch?v=QjR7dimpSJA&t=0m37s
http://www.youtube.com/watch?v=OqV_VHz5BKo
• Similar technology can be used in
a freewheeling system for bicycles
• Allows for drive only in one
direction

22. Front Wheel Drive/Hand Crank Drive?
Could we make the powertrain happen through the front wheels?
• Nope! We can’t run an axle through the front wheels.
• To better address this concern, we looked at front-wheel drive cars. But quickly
realized that any attempt to make the bike front-wheel drive would drastically
increase the cost of manufacturing & assembly
Could we make the powertrain connect to the hand crank?
• Integrating the steering into a hand crank for exercise proved too difficult
• Having steering handlebars AND the hand crank would be impractical (cuz you
know, humans only have two arms n stuff)

23. Upper Body Exercise
• Store-bought dual hydraulic piston system
w/ handles
• Resistance can be adjusted to user’s
preference
• Again, an excellent idea that avoids
‘reinventing the wheel’

24. Steel vs. Aluminum?
We chose to fabricate our works-like-prototype of the
bike using steel tubes instead of aluminum. This is
because we only had one experienced welder on our
student team (Daniel), and he didn’t feel comfortable
trying to weld aluminum due to its high conductivity and
low melting point.

25. Finally Finished!

26. Major Team Contributions
Me!
• Established the initial conceptual framework for the bike’s main systems, namely the
powertrain and disassembly method; assembled the jack axle
• Handled all communication & Report deliveries to Rhoadescar, LLC executives
• Helped think of cheap and reliable ways to manufacture the bike
• Worked closely w/ Walter Webber, CEO of Slipstream Bicycle, to flush out the details of the uhing manufacturing
method
• When we realized that making our own carbon fiber wouldn’t work, I found the cheapest pre-made tubes I could find
(They were on clearance!!)
• Designed all 3D-printed components
Andrew Marione
• Led the research for carbon fiber manufacturing methods, specifically the ‘plug-and-bag’
method & the ‘bladder-mold’ method
• Machined most of the parts
• Came up w/ the idea for the pre-fabricated hydraulic hand exercise

27. Major Team Contributions
Daniel Tepper
• The designated team leader; was very good at keeping us on task and making sure we were
prepared for deadlines
• Made many quick manufacturing decisions towards the end of the project that helped us save a lot of time
• Handled all part orders
• Did ALL the welding
• Led the efforts to research & compile data about general carbon fiber material properties,
PAN vs. PITCH, comparison to aluminum/steel, etc.
• Made revised CAD designs for final design
Lloyd Ambrose (my partner in crime!!)
• Machined parts w/ Andrew
• Excellent at 2D visualization. Provided nice bike renders for our presentations to
Rhoadescar, and came up w/ the logo
• The wheel inside the ‘O’ used to spin, but now it won’t do it anymore and idk why 
bike

28. Major Team Contributions
Chufei Yu
• Handled all the driving! :D
• Did majority of competition benchmarking in Nashville area by visiting
local bike shops
Willie Carter
• Did most of the online benchmarking research
• Did extensive research into the steering conditions for cars, specifically
the Ackerman Condition and caster angles (typically observed in cars)
• Although we found significant inefficiencies in the current ‘Go Boy’ model’s steering geometry, we
decided that it would be outside of our time frame to change it.

29. Needs & Wants, Revisited
• Exciting aesthetic quality
• Intuitive, no lean steering
system
• Multi-gear drive train
• Lightweight design
• Simple repair and
replacement
• 4 Wheels
• Carbon Fiber
• Upper-Body Workout
• Fold/Disassemble
• 20” wide comfort seat
• Capable of seating 300lb
riders

30. Things to Consider Moving Forward
• Abandon the idea of making ‘partially’ carbon fiber bicycles; go all
aluminum instead.
• Not only were the materials expensive, but the dislocations of materials throughout
the bike create discrete stress points (not to mention that drilling carbon fiber is bad.)
• Explore possibility of adding shocks to the bicycles
• More product documentation!
• Statics Charts? Failure Analysis w/ ANSYS or Creo Simulate? Complete parts list?
• Do more research into the Rhoadescar steering linkage; review
Ackerman conditions to see if any power is being lost through turns
• Consider carbon fiber belt-driven system for easier & cleaner chain
removal?
• Stands to support bike sections during disassembly?
• Better ways to keep brake cables out of the way during disassembly