This document summarizes the history of all-composite bicycle frames. It discusses early prototypes from the 1960s, the introduction of production composite frames by Kestrel in the 1980s, and Trek's development of their OCLV line in the early 1990s using technology licensed from Radius Engineering. It describes improvements in Trek's frame construction between 1991 and 1997 that eliminated seams, reduced weight and manufacturing costs, and improved stiffness and fatigue life. The document predicts that further cost reductions could disrupt the bicycle industry by making composite frames competitive with aluminum. In summary, it traces the development and commercialization of composite bicycle frames from early prototypes to large-scale production models.

1. University of Utah
Mechanical Engineering
"All-Composite Bicycle Frames"
Ron Nelson, ClosedMold Composites
Thursday, Jan. 18, 2007
Salt Lake City, Utah

2. All-composite Bicycle Frames Don’t Have Metallic Lugs
• Metallic Lug Elimination Reduces Weight
• Metal Lug Tube and Lug Diameters Are Smaller
Than in an All-composite Frame
– Minimum Wall Thickness Manufacturing Requirements for
Metal Lugs and Need to Reduce Lug Weight
• Composite Structures Use Larger Space Envelopes
Than Metal Because of Lower Density
• Mismatch Results Between Optimum Space
Envelope Between the Metal Lugs and the
Composite Components

3. “Production” Bicycles Impact the Consuming and
Economic Communities
• Production Is At Least 500 a Year, If Not 1000’s
• Significant Market Impact Means Should Be
Considered in New Product Development Efforts
– Generally Safe, Strong, and Reliable, I.E. Meet US CPSC
Tests
– Product Has Met More “Hurdles” Because Production
Startup Funding Was Spent, and Independent People Spend
Money to Buy Them
– You and I Can Afford “Production” All-composite Frames
Because Production Volumes Drastically Reduce Price

4. All-composite Bicycle Product and Inventors
• 1960 Bowden Spacelander, Bowden
• Huffy Custom Frames, Bishop
• Kestrel, Trimble
• Trek 5000, Duplessis
• LeMonde, Calfee
• Trek 5500, Nelson
• Radius HIR, Nelson

5. Patent Chronology and Production Products
Inventor Assignee
U.S. Patent
Number
Patent Filing
Date
Patent Issue
Date
Earliest Filing
Date for
Associated
Patents Product Line
Nelson Et. Al. Radius
Engineerin
g
na 5/29/97 na na none yet
Nelson Et. Al. Trek
Bicycle
Co.
5624519 5/29/92 2/29/97 na Trek 5500, Trek's Line of OCLV
frames
Calfee na 5160862 5/31/91 11/3/92 3/9/89 Sold under Lemond name for a
while
Duplessis na 5080385 5/25/90 1/14/92 11/14/90 Trek 5000, Trek's 1998 line of
all-composite frames
Trimble na 4986949 11/14/89 1/22/91 6/16/88 Kestrel line of bicycles, Radius
worked with in 88'-89'
Bishop et. al. Huffy
Bicycle
4900049 10/18/88 2/13/90 na Huffy semi-custom all-composite
frames

6. 1960 Bowden Spacelander
First All-Composite Bicycle Frame

7. 1960 Bowden Spacelander
Patent

8. 1960 Bowden Spacelander
Was a Commercial Failure
• Monocoque Fiberglass
• Two Halves Joined at
Midplane
• 50 Lb.
• $90.00 Retail
• About 500 Made
• "the bicycle was a
monumental frustration ….
the whole episodes cost him
fortunes"

9. Custom Huffy Frames/bikes Cost Roughly $10,000
Development Was Marketing Driven

10. Production of Cycle Composites Inc.’s Kestrel
Frames Shook the Industry

11. Kestrel Probably the First All-composite Frame Made in
Relatively Large Quantities, >1000/yr.

12. Radius Worked With CCI From
Mid-88’ to Mid-89’

13. CCI Declined to License Radius’ Technologies Freeing
Radius to Work With Trek 1 Year Later
Jim Colegrove/Radius,
He Later Worked
At Trek During and After
Radius Transferred
Technology to Trek

14. Key Players at CCI and My Impressions
• Brent Trimble
– original inventor
• Rich Hollingsworth
– A key in making it work in production
• Bevil Hogg
– president CCI, came from Trek where he was a key in the
Trek 5000 product
• Tom French
– V.P.?, co-owner prior to Schwinn sale?
• Preston Sandusky
– longtime engineer and current owner?

15. Calfee Frame Got Publicity Just As the Trek 5500 Was
Being Introduced

16. Stunningly Simple
Design Concept and Process

17. Similar to Old Brazed Lugged Steel Frame

18. The Trek 5000 - 1988 Model Year Frame
Very Similar to Kestrel in Construction
4,828,781 Duplessis
Duplessis Patents Are
Nearly Identical to Trimble
Patents.

19. Rear Triangle Secondarily Bonded Contrary
to Patent Application and Different From Kestrel

20. Trek 5000 Looked Similar to Kestrel

21. Inside of Trek 5000 Filled With Parasitic
Materials to Aid Molding

22. Improvement in Quality of Trek 5500
Is Obvious and Very Pronounced

23. Trek 5500 OCLV Produced in Higher Quantities and Lower
Costs Putting Kestrel Out of Business
Trek’s John Burke,
Tom Albers, and Bob Read made
a big commitment on the new product
line only a couple of years after the
commercial failure of the Trek 5000. It
required a clear strategic vision and it paid off.

24. Nelson Et. Al. Patent for OCLV
Product Line Assigned to Trek Per License
(also 6,270,104)

25. Radius-Trek Development & Licensing
Contract Signed July 90’ and Production Started in September 91’
……..Only 14 Months to Develop and Implement
Brand New Product and Manufacturing Process…….

26. Trek 5500 OCLV Key Engineers
Committed to Project
Dimitrije
Milovich
Ron
Nelson
John
Short
Rest break during “Product Testing”
on Desolation Ridge, Above SLC, Utah
Proud Radius Engineers
With One of the First Frames
In Waterloo
Late Bob Read of Trek Bicycle
The “Heart & Soul” of New
Bike Project

27. Trek OCLV 5500 “First Assembly”
Was Exciting Moment
John Short “Mingling”
With Production Personnel

28. Preplied Quasi-isotropic Prepreg Die Cut Into Multiply
“Preform” Shapes for Loading Into Mold

29. Quasi-isotropic Die Cut Preforms
Are Pushed Into Mold

30. Bladder Molded Head Lug Cross Section Is
Typical Construction
Bladder Inflated Bladder Deflated
Mold
Mold Mold
Mold

31. Socket Joint Key to Overall Manufacture
“Butt Line” Designed for Positive
Precise Positioning During Frame AssemblyTaper in Plug Designed to
Prevent Shear Failure
“Socket” “Plug” on Molded
Lugs Only
Taper Angle Has to Be Less
Than a Critical Value

32. Monostay Yoke Bladders
Thin Thermoplastic
Bladder

33. Layups Via Finite Element Analysis at Radius
(Pierre Minguet – EIFEL, Mountain Bike Swingarm Too)

34. Milovich & Nelson Surprised and Happy
After Lance’s August 1999 Tour Win

36. Rigid (9900/9800) and Rear Suspended (9500) Mountain Bike
Models Introduced 2nd Model Year

37. Fischer Bike Line Owned by Trek

38. Significant Cost Reductions and Performance
Improvements Can Be Made to 1991 Technology
“holy smoke…those aren’t marcelle waves…
…those are Horseshoe Waves!”

39. Deadly Red-Hot “Horse Shoe” Waves
Fiber Paths Convoluted

40. Successor 1997 Technology
Termed High-Interleave-Ratio Construction
New Design Flexibility Allows Sockets
In Lugs for Lower Cost and
Curved “Plugged” Tubes

41. Illustration of 1991 OCLV Technology
8 or 12 plys at
0/+45/90 degrees
Mold
Die cut
preforms
Mold
“Net” side
preform
“Lap” side
preform

42. 1991 Technology – Cont’d
Full Thickness Multiply Preform “Pushed” Into Female Cavity
Tending to Form Wrinkles
Mold
Mold
Mold
Bladder
“Net” side
preform
“Lap” side
preform
“Lap” side
preform
“Net” side
preform

43. 1991 Technology – Cont’d
Seam at Overlap Between Two Halves
“Net” side
“Lap” side
Seam
“Lap”

44. 1991 Technology – Cont’d
Sockets on Lugs Difficult Because
Overlaps Machined Away
Overlap Material
Removed to Form
Round Socket
Socket Side
Of Joint
Plug Side
Of Joint
Socket Side
Of Joint
Socket Side
Of Joint

45. 1997 Technology “Pulls” Flexible One or Two
Ply Preforms Over Male Shape Reducing Wrinkles

46. Core Removal Step in 1997 Technology
This Patent Owned by
Radius Engineering, Inc.

47. 1997 Technology Produces
High-Interleave-Ratio Construction
Interleave Ratio Is Length of “Seam”
(Path From Inside Part to Outside of Part
Without Crossing Fibers) Divided by Part Wall Thickness

48. Exceptionally High Compressive Strain Delivered in
Frontal Load Test of 1997 Technology Head Lug

49. 1997 Technology Construction Big Improvement
Over 1991 Technology
• Fundamentally Different Structure
– Structurally Weak Crack-prone "Laps" Joining Lug Halves
Eliminated
– Near Seamless Construction Significantly Lighter and Stiffer
• Fiber Waves and Wrinkling in the Lug Walls
Essentially Eliminated
– Major Source of Fatigue Cracking and Lug Failure

50. Big Improvement Over 1991 Technology – Cont’d
• Carbon Lugs and Components 25% Lighter While Being 10%
Stiffer
– Demonstrated in Side-by-side Testing of Batch Runs of Lugs
Made With Old and New Construction
– Due Primarily to Elimination of Laps Between Part Halves
and Laminate Wrinkling.
• As-molded Pinhole Surface Defects and Laminate Wrinkle
(Folds) Induced Resin-rich Surface Defects Are Effectively
Eliminated

51. Big Improvement Over 1991 Technology – Cont’d
• 35%-50% Cost Savings in Prepreg Materials Alone
– Much Lower Scrape Rate and Lighter Finished Component Weight
– Old Complex Preform Shapes Produced Large Scrape Rates
– New Simpler Shapes Allow Near Zero Cutting Scrape
• Fewer Tools and Presses For Given Production Rate
– One Half to One Fourth the Number of Tools and Presses
– Part Lay-up Occurs Separate From Molding
• Allows Greater Design Flexibility
– Plug and Socket Joints to Be Configured and located As Needed
– Fiber Orientation and Laminate Wall Thickness Tailored Throughout
Lug

52. • As Dr. Dan Said "Those Aren't Marcelle Waves…Those Are
Horseshoe Waves“
• Small Marcelle Waves Are Known to Reduce Strength
Substantially, But These Waves Aren’t Small
• Specific Strength Is up 10% while Specific Stiffness Is up 30%
– Easier to Control and Improve Stiffness More Than to Improve
Static Strength
– Fiber Waviness elimination Explains Higher Stiffness
Big Improvement Over 1991 Technology – Cont’d
No more Horseshoe waves

53. Possible Developments in Next 2-3 Years
• Large Price Reduction in All Composite Frames
Problem for Large Bike Companies
– Multiple Product Lines Defined by Different Frame Materials
– Improvement in One Product Line Not As Important As Effect
on Company As Whole
• Cheaper All Composite Frames Could Wreck Havoc
With Existing Aluminum Product Lines
• So a New Low Cost All Composite Line Would
Cannibalize Allot of Existing Sales

54. Award Winning Closed-Mold Composite
Sporting Good Products

55. Award-Winning Closed-Mold Composite
Sporting Good Product