Our strongest, lightest carbon yet
OCLV Carbon is Trek’s patented carbon fiber process, the result of more than 25 years of experience building the world’s finest carbon fiber bicycles in Waterloo, Wisconsin, USA. Experience matters, especially when working with a material that holds seemingly endless possibilities but presents such unique challenges as carbon fiber. To understand the best technology, you have to build it, and we’ve been doing just that since 1991.
Why OCLV Carbon?
A well-built carbon frame dramatically reduces weight compared to metallic materials, while maintaining the strength and stiffness that high performance bicycles and their riders demand. This is where Trek’s pioneered and patented OCLV Carbon—an acronym for Optimum Compaction Low Void—process comes in. OCLV Carbon frames begin with the best material available. Trek has spent countless development hours perfecting the construction of a variety of weights and types of carbon (cloth, unidirectional, etc.). The OCLV process is best explained when broken down into two parts:
Optimum Compaction: Carbon is layered into a series of plies compacted to the ideal fiber-resin ratio. The process starts with cutting carbon fiber from large sheets to a specific shape which is then placed into a mold. A combination of heat and pressure then compresses the sheets of carbon into a carbon lug. This combination of heat and pressure is OCLV’s most essential and closely guarded equation.
Low Void: Voids are the spaces that exist between the layers of carbon fiber that comprise a component or frame. Minimizing these voids is the primary goal of quality carbon engineering, as more voids translates to reduced strength and durability of the composite material. OCLV Carbon exceeds aerospace standards regarding the number of voids in its material.
Shapes matter
In addition to sizeable reductions in weight, the largest advantage of carbon fiber frames over another material are the limitless shapes that the material can be molded into. Different shapes exhibit different strength, stiffness, and aerodynamic properties.
Trek utilizes Finite Element Analysis, a comprehensive software simulation toolkit, to tell us exactly how different shapes will respond to different riders and riding surfaces. We utilize proven theories of fluid mechanics through Computational Fluid Dynamics in order to explore the aerodynamic properties of various designs. Our bikes are conceived with computer-generated designs, fluid-dynamically assessed and finite analyzed, and the resulting shapes appear seamlessly machine-made. At the end of the day, these complex scientific investigations are applied in a hands-on, ground-up process that combines multiple molds with a variety of carbon materials to result in a magnificently engineered and largely hand-built product.
Built to last
Trek builds bikes to last and we stand behind every one that we bears our name. Just as the first Trek hand-welded over forty years ago in a red barn, our first full carbon frame is still under warranty. All OCLV Carbon bicycles come with a limited lifetime warranty, because we believe that more people riding bikes is in everybody’s best interest.
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Kammtail Virtual Foil
What is Kammtail Virtual Foil?
KVF (Kammtail Virtual Foil) is an unconventional aerodynamic shape designed to employ the advantages of airfoils in a cycling-specific platform that is light, stiff, and performs well in crosswinds. KVF is the result of a nine-month engineering project dedicated to the development of low-speed airfoil technology.
Airfoils are designed to reduce the amount of drag a rider experiences by employing a streamlined shape to frames and components. In contrast to a traditional teardrop-shaped airfoil, KVF is a unique truncated-tail design. This design greatly improves not only aerodynamic drag but also increases lateral stiffness, reduces weight, adds stability in crosswinds, and provides a more comfortable ride with additional vertical compliance.
What is the benefit?
Designing airfoils for bicycles requires a great deal of creativity, as the traditional designs utilized by airplanes and automobiles do not consider the unique properties of cycling aerodynamics. The relatively low speed and forward thrust of bikes makes them far more vulnerable to environmental factors such as crosswinds, and requires technology that focuses on more than improving headwind aerodynamics. Bicycle tube shapes inherently exhibit a great deal of curvature and combined flow interactions, further complicating the process of creating a truly aerodynamic design.
While airfoils typically extend to a pointed end in a teardrop-type shape, Kammtail features a truncated, square end that increases stiffness and mimics the performance of a much longer, wing-like foil.
Airfoils are defined in terms of aspect ratio, or the relative surface area between the total width and profile of a frame or component. As aspect ratio increases, drag decreases. Yet, as with all things in life, there is a tradeoff to high aspect ratios. Stability, weight, and stiffness suffer proportionally as the aspect ratio grows. Professional cycling’s governing body, Union Cycliste Internationale (UCI), places significant limits on how extreme this ratio can be, limiting the maximum to minimum transverse dimension ratio to no more than 3:1.
How Trek's engineers solved this problem
Trek’s engineers set out to achieve the aero performance of a high aspect ratio within a compact, light profile that would be stiff, stable, and comply with UCI regulations. Veteran engineer Doug Cusack teamed up with new addition Paul Harder to investigate platforms for a cycling-specific airfoil. As Paul explains, “at the time, bicycle airfoils (industry-wide) were being designed using an old system for defining airplane wing airfoils. I saw this as a major disconnect and decided to study airfoils as they truly apply to bicycles as my first “personal” R&D project.” In order to test as many designs as possible, the team created a new approach to computational fluid dynamics (CFD) that acts as a virtual wind tunnel capable of testing 3D drawings. This more efficient approach allowed Trek to test more than eighty different shapes, something that would have never been possible in the wind tunnel. Doug had a hunch that truncating an airfoil could lead to a breakthrough in aerodynamic efficiency, and the CFD results the team saw with such designs exhibited unprecedented results. KVF was born.
The new design solved a fundamental problem with previous platforms. Bike airfoils have very high curvature compared to a more stretched out airplane wing or stabilizer type of airfoil, and bikes also experience much higher yaw, or a larger angle between apparent wind (often inconsistent and coming from the side) and the direction of bicycle motion. The larger this angle is, the more unwanted lateral movement the bike will experience. As a result, air has a very difficult time staying attached to the airfoil wall and tends to separate, causing large amounts of drag and reduced stability. The truncated design of KVF solves this curvature problem by using the portion of a high aspect ratio that works the hardest, (the front), and doing away with the pointed rear that is less important in cycling-specific applications. Winds flow around the front of the foil like a traditional design, and stay on this trajectory because truncating the shape reduces its curvature. As yaw and crosswinds increase, so does the performance advantage of KVF.
KVF performs like an 8:1 aspect ratio foil in headwinds, but complies with UCI’s 3:1 regulation. The shape can be applied to virtually every surface on the bike, including fork legs, downtube, seat tube, seatstays, and handlebar. As a bonus, KVF is an inherently wider shape than a traditional teardrop airfoil, and provides improved bike handling as a result of increased lateral stiffness.
KVF just keeps getting better
KVF was initially developed as part of a larger project to build the world’s fastest bicycle. Once the truncated design of KVF reached proof-of-concept in CFD analysis, our engineers constructed a complete prototype and took it in for extensive testing at the A2 wind tunnel in Mooresville, North Carolina and later at the San Diego Wind Tunnel in California. They were impressed with the results, and this bike soon became the original Speed Concept, Trek’s wildly successful triathlon platform. The benefits of this bike to triathletes were so immediately apparent that the engineering team soon began to expand the application of KVF to traditional road racing bike designs.
KVF was easier to integrate into the smaller surface area of traditional road frames than previous airfoil designs, allowing new conceptions of aero road bikes to come to life. Madone, Trek’s high-performance aero race bike, was brought into the fold with KVF technology in 2013. Speed Concept has since been revamped and is faster than ever, thanks in large part to a revised KVF with less frontal area and reduced drag at all yaw angles. The 2016 Madone also features an improved design in which KFV is an integral element. Trek’s engineers continue to search for more applications for this amazing technology, and have seen great success expanding it to more components such as handlebars.
Is it proven?
KVF’s design has been widely replicated in the years since Trek’s engineers first unveiled it. Though we’re flattered that so much of the industry has adopted KVF-like design, we still push the limits of what KVF as a subtle technology can help a rider accomplish. As Paul says, “by nature, the KVF design must be highly-engineered, and casual knowledge of Kamm-style airfoil construction and theory is not enough to design a high-performing KVF.” That, it seems, can only be left to those who discovered and perfected it.
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Aerodynamics
When the margin of victory is measured in thousands of a second, every inch, every gram, every angle matters. In the effort to move an object through air in the most efficient manner possible, Trek engineers dream, draw, build, test, and repeat. The countless hours of development and work are paid in the raised arms of thousands of athletes the world over grateful to have met their challenge. Whether its ever spoken, every age group triathlon, every World Tour Time Trial, every coffee ride sprint finish, the work of Trek's Analysis Team plays a role.
Wind tunnel testing
Ideas you can argue. Data you cannot. So when it comes time for the hard math of Trek's aerodynamic development efforts, the laboratory becomes a little more claustrophobic. The wind tunnel is the perfect laboratory for testing the aerodynamic performance of cycling equipment and Trek has been committed to its use for over two decades of development. Tested in the same tunnels used by aerospace engineers, equipment design breakthroughs such as Kammtail Virtual Foil and Bontrager's Aeolus line of aero wheels have been tested in the wind tunnel and proven on cycling's biggest stages.
Manny
A key member, though typically unheralded, of Trek's Analysis Team is the aerodynamic mannequin the team has lovingly dubbed, "Manny." More the strong silent type, Manny, is an inanimate surrogate capable of a pedaling motion that addresses the muscular limitations of human design by being able to hold a consistent aerodynamic position for however long required by the team. This allows the Analysis Team to work specifically on whatever they are trying to prove during their time in the tunnel. And at the end of the day, Manny conveniently folds into a custom made case easily checked on all major airlines.
Track testing
Though a wind tunnel will produce accurate data regarding a rider and their bike's aerodynamic potential, races are not contested in wind tunnels. A rider has to be able to hold a position for a given period of time for the lessons of aerodynamics to be applicable. Refining a rider's aerodynamic position in movement takes place on an indoor track where Trek's Analysis and Precision Fit teams can collaborate on finding a rider's optimal aerodynamic position.
Computational Fluid Dynamics
Computational Fluid Dynamics (CFD) is a program that Trek engineers deploy throughout various development cycles to test early tube shape concepts that exist only as three dimensional drawings. CFD acts as a virtual wind tunnel to test the aerodynamic potential of the drawing to determine whether prototyping can continue or further refinement is required. It’s aided Trek in our most important contributions to aerodynamics including Kammtail Virtual Foil and Bontrager’s Aeolus wheel line. While CFD cannot completely replace the need for wind tunnel testing, it can drastically reduce development time and turn ideas into reality much faster.