composites in bicycle manufacturing
TRANSCRIPT
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Composites in BicycleManufacturing
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Overview
Basics of frame geometry
Background and history
Focus on:
Titanium frames Carbon Fiber frames
Kevlar frames
Video of composite frame construction
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Basics of Frame Geometry
Mountain Bike Frame Design
Angled top tube
Front/rear springs
Heavier construction
Relaxed rider position
Aggressive fork rake angleForgiving design for crashes!
Greater rider movement about bike
Road Bike Frame Design
Springs are atypical
Emphasis on less weight
Top tube parallel to ground
More aggressive rider position
Less flexibility on rider movement
Stiffer frame design for responsiveness
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Basics of Frame Types & Geometry
Basic Frame Types:
Diamond: The most common sport version
Step Through: Commuter focus
Recumbent: Ergonomics and aerodynamics
Truss: Precursor to Diamond
Monocoque: Typically Al, hollow shell
Penny-Farthing:
Bicycle Jig Construction:
Common across all frametypes, with monocoque &
some composites the
exception (molding instead)
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Background Wood & Steel
Precursor to the modern bicycle The Draisienne
Primarily wood construction
Incidentally, the inventor is also credited with the
first cycling traffic fine: for running over a
pedestrian!
Velocipedes and Penny-Farthings soon followed
From Penny-Farthing to today
Penny-Farthing comprised of low-
carbon spring steel
Followed a similar path as aircraft
construction always moving to
lighter, stronger alloy steelsCommon steels used today are often
4130, or Chromoly
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Background - Aluminum
Aluminum Frame Construction:
Far better strength-to-weight ratio, machinability, and lower stiffness than steel equivalents
Introduced the use of TIG welding in bike manufacture, as well as hollow-tube forming such as
with monocoque frames
There are even CNC-machined Aluminum frames!Typical Aluminum alloys are 6061 and 7005
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Background - Titanium Alloys
TitaniumAlloy bike frame construction
6/4 and 3/2.5 the most common alloys
Gaining steady popularity in recent
years due to desire for lower weight vs.steel and higher stiffness vs. Aluminum
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Focus on Carbon Fiber
Carbon Fiber-based tube frame construction:
Is able to utilize all major forms of bicycle frame manufacturing:
Tube-to-tube techniques
Monocoque/molding techniques
Latticework techniques
Material type ranges from 1k to 15k tow, plain weave
Preimpregnated epoxy is still uncommon, but gaining in popularity
Bike material of choice for racers
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Focus on Carbon Fiber
Focus on Carbon Fiber
Carbon Fiber is also an excuse to pursue more esoteric designs:
Recumbent racing bikes
Ultra-lightweight folding designs
Artwork/ off-the-wall designs
These designs often retain full
functionality!
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Focus on Kevlar Fiber
In Truth.
This is a Kevlar/Carbon Fiber composite
bike frame
Utilizes a latticework construction with
kevlar/carbon roving
Three-dimensional triangulation for
superior column strength and resistance to
buckling/bending
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Focus on Kevlar Fiber
Kevlar/ latticework manufacturing and research
hook-and weave construction methodology (patented, of course!)
1:12 weight ratio vs. Steel of comparable strengths1lb of lattice material supporting 11,600lb reinforced concrete block
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Carbon Frame Construction Video!
http://www.youtube.com/watch?v=2nVbmcnsXXs&feature=related
Manufacturer name is Trek
Monocoque construction demonstration
Sorry for the length (6 minutes), but its good stuff!
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Thank You
Any Questions?
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References
http://www.phred.org/~josh/build/design.html
http://blog.velocite-bikes.com/carbon-fiber/
http://www.delta7bikes.com
http://www.jamisbikes.com/usa/thebikes/road/xenith/nearnet_xenithsldi2.html
http://en.wikipedia.org/wiki/Bicycle_frame
http://en.wikipedia.org/wiki/Bicycle