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Full text of "NASA Technical Reports Server (NTRS) 20020086324: Bicycle Wheel"

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Bicycle Wheel 

At right, Mark W. 

Hopkins displays the 
new aerodynamic wheel 
for racing bicycles he 
designed with colleague 
Frank S. Principe. Both 
engineers are members 
of a “Wheel Team” 
organized by the 
Advanced Composites 
Division of E. I. duPont 
de Nemours and 
Company, Wilmington, 

Delaware. The team 
developed the wheel in 
conjunction with 
Specialized Bicycle 
Components, Inc., Morgan Hill, California, employing 
duPont composites technology with NASA 
aerodynamic and computer modeling technology. 

At racing speeds (25-35 miles per hour), 
multispoked wire wheels create considerable speed- 
trimming drag. Newer disc wheels offer less but still 
significant drag and their large surface areas make 
them difficult to control in crosswinds. To obtain 
even lower aerodynamic drag, Principe and Hopkins 
decided that the design should be as thin as possible 
and should have the fewest spokes that would 
support the loads the wheel would encounter. The 
design effort was a complicated task because the 
thinner the wheel and spokes, the more difficult it 
becomes to obtain adequate lateral stiffness. 

The duPont engineers conducted extensive 
research on the latest data available relative to drag 
coefficients for NASA 
airfoils and determined 
an optimum profile to 
balance aerodynamic 
and structural needs. 

The basic design they 
selected is a three spoke 
wheel, each spoke in 
effect an airfoil, with a 
blunt leading edge and a 
thin trailing edge to 
maximize aerodynamic 
efficiency as the spoke 
moves through the air 
like a helicopter’s rotary 
wing. To get the 
requisite stiffness, they 

employed a composite 
material of epoxy resin 
reinforced by fibers of 
carbon, glass and 

After establishing 
the basic geometry, the 
team used sophisticated 
computer modeling 
techniques to engineer 
the material to the target 
weight and stiffness. 
Modeling was 
accomplished by use of 
NASTRAN® computer 
programs (NASTRAN is 
an acronym for NASA Structural Analysis; MSC/ 
NASTRAN is an enhanced proprietary version by 
MacNeal-Schwendler Corporation). 

The final product met its targeted performance 
goals and has a retail price of $750. Introduced in the 
spring of 1990, the wheel is manufactured by 
duPont’s Pencader Composite Part Fabrication Plant, 
Newark, Delaware. Specialized Bicycle Components 
handles promotion and marketing. 

®Kevlar is a registered trademark of E.I. duPont de Nemours 
and Company. 

®PATRAN is a registered trademark of PDA Engineering. 

®NASTRAN is a registered trademark of the National Aeronautics 
and Space Administration. 

The basic 
design is a 
three spoke 
wheel, each 
in effect 
an airfoil