Bill Shook obsessively engineers every wheel system to its optimal “sweet spot”, the balance of spoke tension, hub flange width, spoke angle and selection of the appropriate materials. After years of research and development, Bill Shook designed the American Classic three group spoke lacing for our 24 spoke rear wheel systems to build the strongest, stiffest and lightest road rear wheels in our line. We call this advanced system Series 3 for our 420 Aero 3, Magnesium, Road Tubeless, Aluminum Tubular and Carbon wheels. These good looking, hand built three group spoke wheels are at the forefront of performance, aerodynamics, comfort and durability.
The concept behind this lacing pattern is to create equal spoke tension for the drive and non-drive sides of the rear wheel, a state that cannot be reached in traditionally spoked wheels. Mathematically, this unique balance of spoke tension occurs on 24 spoked rear wheels. To achieve this balance, the rims are drilled in groups of three spoke holes. The spokes are laced to our finely crafted American Classic high-low 24 spoke hub, two on the drive side of the wheel to one on the non-drive side. The result is more spokes on the drive side where the wheel needs to be strongest, and fewer spokes on the non-drive side. Bill Shook calculated the optimal position for the non-drive side hub flange to create the ideal bracing angle of the non-drive side spokes. “The three group spoke design is a better use of materials achieving the balanced use of the spokes with equal spoke tension on both sides of the rear wheel,”says Shook.
The wheels are stiff and light to decisively dive into corners and power out, accelerate repeatedly, climb and descend with ease and hold speed on the flats. There are no broken spokes. No flexy feeling out of the saddle. When winning is your goal, the time-tested three group spoke wheel system delivers.
Carbon fiber is composed of extremely thin, bonded fiber made of carbon atoms. Thousands of carbon fibers are bundled together into cloth-like sheets. The sheets are combined with plastic resin. The sheets are placed into a mold with the fibers oriented in specific directions to create the desired characteristics of strength, stiffness or flexibility for the completed rim. Carbon fiber is used in wheels because of the high strength-to-weight ratio, low weight and the ability to mold the sheets into aerodynamic shapes. The subject of intense study in cycling, aerodynamics is the air flow over and around your wheels, bike and body as you ride. The goal of aerodynamics is to reduce the wind resistance called drag on your equipment, so the rider slices through the air and goes faster. At slow speeds, there is smooth air flow called laminar flow. As speed increases, the laminar flow turns to turbulent flow. There is a “sweet spot,” the point of reduced drag, when the air begins to tumble over and across the wheel surfaces in turbulent flow. The key to top carbon fiber wheel design is to produce rim shapes that optimize, capture and maintain the aerodynamic sweet spot for each rim depth.
Bill Shook started the engineering process on our carbon fiber rims from the inside, dictating the direction and lay up of the fibers to form stronger internal spoke beds for structural integrity and stiffness. He then moved to the outside of each wheel, designing unique features for aerodynamic performance to achieve the “sweet spot”. Carbon 38, Carbon 44 and Carbon 50 are the most challenging shapes because of their minimal surface area. Bill designed a gentle curved shape down to the spoke bed to minimizing drag by bringing the air flow back together without turbulence. Carbon 58 tubulars and clinchers have a recurve shape under the brake track. The recurve shape creates air pressure fluctuations causing a ripple effect to induce turbulent air flow to reduce drag at higher speeds. Carbon 85 tubulars are a semi disk shape with no spokes near the leading edge of the wheel. Bill designed the large, smooth carbon surface bringing air back together reducing cavitation behind the spokes. Carbon TT Disk is the ultimate in aerodynamics with lenticular skins to sustain the sweet spot for maximized power output.
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