Composites in Bicycle Manufacturing

8/6/2019 Composites in Bicycle Manufacturing

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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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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

Composites in Bicycle Manufacturing

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