1. Kestrel introduced bladder-molded monocoque
to the industry in 1986. Carbon fiber composites delivered the best
of all worlds – stiffness, strength, lightweight, formability,
corrosion resistance, shock damping – for a superior ride.
The use of Aerospace-grade carbon/epoxy “pre-preg” materials
would revolutionize bicycle frame design and manufacturing and change
the sport forever.
2. Our Modular Monocoque construction combines the best of the multi-patented
Kestrel frame technologies, EMS fork technologies and structural bonding
techniques that we’ve honed for two decades. A one-piece, hollow
bladder-molded main frame is joined to separately bladder-molded rear
sub-assemblies using advanced bonded joint designs and aerospace adhesives,
yielding a single Modular Monocoque frame structure.
[ref “why kestrel” info on website]
3. Kestrel was the first company to use higher-stiffness “intermediate
modulus” carbon fiber, dating back to 1989 and the 200 EMS. In
fact, Kestrel’s use of Hercules “IM-8” fiber pre-dated
the US Air Force’s qualification for the F-22 Raptor prototypes
by two years.
4. Kestrel introduced the world’s first all-carbon composite
bike frame, the Kestrel 4000, in 1986 for the 1987 model year. The
4000 was also the first production frame with aerodynamic “tube” sections.
5. Kestrel was the first bicycle company to employ true aerospace
carbon fiber engineers, starting back in 1986, with engineers from
such companies as Lockheed Missiles & Space, Aerojet Strategic
Propulsion and the US Air Force Advanced Composites Program. The original
Rocket Scientists of the bike industry.
6. Kestrel engineers have set up carbon fiber frame manufacturing
plants in the US (three separate facilities), Japan and China. We have
acted as consultants on manufacturing equipment, processes and quality
control to today’s major Asian carbon frame suppliers. We’ve
been there and done that so we know exactly what it takes; and we know
exactly what to monitor to insure that Kestrel’s strict engineering
and quality standards are met.
7. Kestrel introduced the world’s first all-carbon mountain
bike, the MX-Z, in 1988. This bike dispelled the myth that carbon fiber
composites could not stand up to off-road use and abuse.
8. Kestrel introduced the world’s first all-carbon triathlon
bike, KM40, in 1989. One of the first bikes to adopt a forward, 78-degree
seat position and dual 650C wheels, the KM40 also was the first production “tri
bike” to utilize aerodynamic tube sections.
9. Even Kestrel’s owner/operators are aerospace-trained carbon
fiber engineers, including its President and its Product & Marketing
Director. These two individuals alone represent more than 40 years
of carbon fiber engineering in both design and manufacturing.
10. Kestrel provides design and manufacturing
engineering to several
automotive aftermarket companies.
11. World’s first monocoque carbon road fork, the “EMS
Fork”, introduced for 1989. With its higher stiffness, lower
weight and smoother ride over the existing metal forks, the EMS literally
created a new market segment. Carbon forks are now standard spec on
virtually every high-end road and tri bike.
12. Kestrel’s full-carbon “Nitro” MTB prototype of 1988 was the predecessor to the full-suspension craze. The bike
featured the first-seen prototype of what was to become RockShox, as
well as ingenious approaches to high-forward pivot design, linear-pull
brakes and on-the-fly suspension lockout. In 2001, the Nitro was selected
by Mountain Bike magazine as the second most important mountain bike – ever.
13. 1992 – the Kestrel 500 SCi is the first
modern seat-tubeless design. Kestrel engineers fully exploit the unique properties and formability
of carbon fiber, creating a structure completely unattainable with
traditional metal frame materials and providing improved aerodynamics,
a silky-smooth “passive suspension” ride and stiffer-than-steel
bottom bracket response.
14. The 1999 KM40 Airfoil becomes the first molded composite frame
completely designed utilizing 3-D Solid Modeling techniques. Kestrel’s
advanced design is so complicated in form that not even the engineers
who developed the Solid Modeling software can replicate it. Instead,
custom-modified code must be used to input the KM40’s complex
curves and blends.
15. Aluminum rivnuts, stainless rivets. There you have it, the entire
list of “off the shelf” items that go into a Kestrel frame.
Because every Kestrel – road, mountain or tri – is designed
entirely from scratch by our team of engineers and designers, from
the proprietary modular monocoque composite structure to the model-exclusive
machined, stamped or forged details that finish it off. Unlike our
competition, we don’t use any pre-made, generic-design tubesets,
stay assemblies, or metal fitments.
16. No generic “private labeled” forks, either. Every
Kestrel road and tri frame comes with its own model- and size-specific
Kestrel fork design, based on over 17 years of experience in making
the finest carbon forks available.
17. Proprietary Bonding Design and Techniques. In addition to our
pioneering development of monocoque carbon molding, Kestrel has employed
engineering-grade structural adhesives and bonded joint designs since
day one. We design our bonds correctly, loading the adhesive in “shear” for
optimal strength, with properly maintained adhesive gap for reliability.
Typically, the bond is over-designed so that its strength surpasses
that of the carbon structure itself. It’s light-years from gluing
a bunch of separate tubes and lugs together.
18. Even our bonding adhesive is better than what the other guys use.
While others specify a cheaper, quick-cure single stage glue, Kestrel
engineers insist on using the highest quality, aerospace grade 2-part
structural epoxy adhesive. This adds time – and cost – to
our manufacturing process, but it also provides the strongest bonds
possible. We wouldn’t have it any other way.
19. Every Kestrel carbon fiber frame, fork, handlebar and seatpost
is covered by our legendary Lifetime and No-Fault Warranties.
[ref “warranty statement” on website]
20. All Kestrel frames, forks and components are built using unidirectional,
long-filament pre-preg composites. We use long-filament 700K
and 800K carbon for the superior strength you get from continuous fiber runs,
and we can tune each structure with careful fiber orientation. Our
pre-preg carbon - meaning it's pre-impregnated with resin - uses a
proprietary, toughened thermoset resin matrix. A fancy way of saying
we employ a tough, strong epoxy to hold our carbon together. By using
pre-pregs we're able to ensure an optimal fiber-to-resin ratio in the
completed part, what you'd call lightest and strongest. This is the
preferred way of building carbon parts, that’s why it's employed
in Aerospace, Formula 1 racing and virtually all other high-performance
21. Carbon fiber has the best stiffness-to-weight and strength-to-weight
ratios of any frame material, with infinite fatigue life and a shock-damping
capability 10-15 times that of metals. But not all carbon is the same
- there are different grades of carbon, just as there are different
grades of metals. We use two different grades of carbon fiber, 700K and 800K. The "K" is short for ksi, which denotes the material's
tensile strength in thousands of pounds per square inch. So 700K carbon
can withstand a tensile load of roughly 700,000 pounds per square inch
of material. And 800K is even stronger, taking an 800,000-pound load.
For comparison: chrome-moly steel falls into the 63-97 ksi range, 3Al/2.5V
titanium is 73-90 ksi, 6Al/4V titanium is 128-138 ksi, 6061-T6 aluminum
is 40/45 ksi, and 7075-T6 aluminum is 73-83 ksi.
But even more significant is stiffness, since a stiff frame that resists
pedaling forces is a more efficient one. Carbon's stiffness trumps
other frame materials, hands down. Our 700K carbon has a relative stiffness
(or Elastic Modulus) of 33.4 million pounds/square inch (msi), and
the 800K fiber we use is 42.7msi. (Chrome-moly steel, the stiffest
metal used in bicycle frames, comes in at 29.7 msi, 3Al/2.5V titanium
is 14.5 msi, 6Al/4V titanium is 16.5 msi, while 6061-T6 and 7075-T6
aluminum are 10.0 and 10.4 msi, respectively.)
[ref “About Carbon” page of our Technology section]
22. Carbon composites offer 10-15 times the shock-damping
capabilities of any of the metal frame materials. Which means that, unlike with
metals, you actually can feel the difference. With metal structures,
the only way to absorb road shock (without incorporating suspension
devices) is through flex, so comfort and efficiency become polar opposites.
With carbon fiber composites, the inherent damping of the material
is substantial enough that the comfort of the frame can actually be
addressed separately from its structural performance. The result – a
strong, stiff Kestrel frame or component that provides an incredibly
efficient ride, yet smoothes out the road and tracks like nothing else.
23. Optimized Tube Shapes and Junction Design. Everything on a Kestrel
frame is designed for optimal performance of the task at hand. Tubes
and junctions are sized and shaped for the given loading conditions
and functional requirements. Tube sizes and shapes continuously vary
from one end to the other; bottom bracket and head tube areas are massively
reinforced; stays are formed to provide tremendous lateral stiffness
while adding to the signature smooth ride.
24. Size-Specific Structural Design and Fiber
Layup. Kestrel engineers
vary the type, amount and ply angles of our carbon fiber pre-preg materials
throughout each frame design, to suit the structural needs at literally
every point in the frame. This maximizes performance and ride quality
while eliminating unnecessary weight, regardless of frame size. Plus,
tube and junction sizes are actually designed in proportion to each
individual frame size for consistent stiffness, response and ride throughout
the line. In fact, in some models every tube and junction is scaled
proportionally to every frame size.
25. Ride Tuned Stays. Our Modular Monocoque seatstay and chainstay
sections are engineered for efficient power transfer and lateral tracking,
while at the same time enhancing the already silky-smooth carbon ride.
Hollow, bladder-molded stay assemblies combine the best of Kestrel
frame, fork and bonding technologies. Add to this design details such
as functional aerodynamics, and our size-proportional sections and
fiber layup techniques.
26. Exclusive and Proprietary EMS Fork Technology. Every Kestrel road
and tri model frame comes with its own design-specific Kestrel fork.
Each is designed and manufactured using our legendary and proprietary “EMS” fork
technology and, like our frames, held to the highest engineering, quality
and reliability standards in the industry. Every aspect – from
materials and processes, to geometry and functional styling, to performance
and ride quality – is designed to work in concert with and enhance
the Kestrel frame.
27. Proven No-Compromise Geometry and Fit. Kestrel road, mountain
and tri geometries have been tweaked and refined over two decades,
with input from some of the premier sizing and fit experts in the industry.
Geometries are based on classic center-to-center dimensions - we don’t
compromise with one-size-fits-all designs or marketing fads. And since
each size of each frame model requires its own unique set of costly
CNC-machined tooling, the geometry spec’s for each size can be
designed without the shared tube angles, lengths or junctions commonly
found on volume manufacturers’ frames. As a result, Kestrel frame
models provide size-proportional fit and consistent performance throughout
28. Every millimeter of the Airfoil Pro tri
bike is designed
to minimize drag and provide high-speed stability. Case
in point: Our engineers employ extensive wind-tunnel test knowledge
to push the aerodynamic “center
of pressure” as far rearward as possible. This precise
redistribution of side surface area maximizes crosswind stability,
plus it reduces
drag by taking full advantage of the forward lift vector generated
by those same crosswinds.
So the only ones being blown away are your competitors …
29. The 2006 Airfoil Pro combines exacting new carbon/epoxy
materials processing with fine-tuned ply
orientation for increased torsional
stiffness and bottom bracket rigidity. The result – a faster,
more efficient bike that retains its signature smooth ride and wind-cheating
30. Kestrel wrote the industry handbook on carbon bicycle design,
and our engineers are constantly adding new chapters.
31. Kestrel introduced the world’s first one-piece molded carbon
road handlebars, the “EMS Pro” series, in 2001. Lighter
and stiffer the then-standard aluminum bars, with a smoother ride,
an unlimited fatigue life and a Lifetime Warranty.
32. Every tube and stay on the Evoke features
unique, continuously varying cross-sections over its entire length, for optimal use of our
proprietary 700K Carbon Fiber. Kestrel engineers employ 3-D Solid Modeling
software to develop each size’s proportionally scaled
tube and junction profiles, for consistently superior stiffness, response and
ride quality throughout the size range.
33. Every Kestrel design is proprietary-we engineer everything in-house
in Santa Cruz, California, beginning with computer-aided design & analysis
and ending with exacting manufacturing procedures and quality standards.
While other companies may simply order up a mass-produced, generic-design
carbon frame from a nameless factory and slap their own stickers and
paint on it, we engineer every Kestrel from scratch.
34. Ever notice how some of our competition’s bikes look like
Kestrel designs of ten or more years ago? We have…
35. Kestrel Engineering specifies the most
rigorous qualification testing of carbon products in the bicycle industry. Twenty years of
prototyping, manufacturing and testing of carbon frames, forks and
components gives us a proprietary database that has proven effective
time and again. While other companies rely solely on certain commonly
accepted “standards” as well as the advice of their outside
suppliers, Kestrel goes the extra mile to consistently produce the
most reliable, best performing products on the market. Yes, it’s
more costly to produce products that satisfy our testing requirements,
but we believe it’s a better value at the end of the day.
36. Fiber Areal Weight (faw) – is the weight of the fiber portion
of a given quantity of fiber/matrix pre-preg material; usually expressed
in grams-per-square meter, or gsm. For example, a carbon/epoxy pre-preg
with a faw of 150 gsm contains 150 grams of carbon for every square
meter of material. Similarly, one square meter of 110 gsm material
would contain 110 grams of carbon. Since the comparative surface area
is fixed (one square meter) the difference in fiber weight will determine
the thickness of the layer, or “ply” of pre-preg material.
Note that faw has nothing to do with the stiffness or strength properties
of the material, but is merely an indication of the fiber weight and
therefore the ply thickness of the material.
Lowering the faw of a given fiber will make the ply thinner and lighter,
but will also decrease the structural properties. However, when employing
a stronger, stiffer material - such as Kestrel’s 800K carbon
- the faw can be reduced proportionally to provide a thinner, lighter
structure while retaining sufficient stiffness and strength in the
In fact, Kestrel was the first to combine a lower faw with higher
grade, high strength/high stiffness fibers to produce ultralight carbon
frames, starting with the 200 EMS back in 1989. Years before the industry
marketing machines caught on to this concept.
37. The Airfoil Pro comes in a full range
of six sizes – from
47cm to 59cm, to fit a wide range of athletes. Yet each and every size
features its own unique set of geometry and fit specifications. Head
angles and seat angles are dialed to the nearest quarter-degree, to
provide consistently superior fit and finely balanced handling throughout
the range. Even wheel diameters are proportional, with 700C wheels
on 54/56/59cm frames and 650C on 47/50/52cm versions. So you get the
best fit and fastest ride possible, regardless of your frame size.
38. The Evoke comes in a full range of seven
sizes – from 47cm
to 62cm. Yet each and every size features its own unique set of geometry
and fit specifications. Head angles and seat angles are tweaked to
the nearest quarter-degree, to provide consistently superior fit and
finely balanced handling throughout the range. We don't cut
corners to save in tooling or production costs. So you get the best ride possible,
regardless of what size frame you ride.
Production Perfection | No-Compromise
Materials | About Carbon | Anatomy
of a Kestrel