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Carbon Fiber Wheels: FAQ

Carbon Fiber Wheels: FAQ's

What performance gains can I expect by upgrading to BST wheels?

A: UK sports bike magazine, SuperBike, performed an independent two-day test at Spain’s Almeria circuit using a Honda FireBlade - which already has as original equipment particularly light wheels. The bike was in a mild state of tune, representing a typical modified road/street/track day sports bike by having; race exhaust, Dynojet Power Commander, double-bubble screen, Sprint steering damper, a two teeth larger rear sprocket and upgraded brake pads. The rider was already familiar with the circuit after having ridden there twice before. The first day’s testing took place with standard wheels and the only change for the second day was the substitution of BST wheels. Weather conditions were unchanged and the following was observed: - Acceleration was noticeably stronger with the rider reporting “it felt as though it had gained ten horsepower” - The bike could be braked later - The bike could be turned more easily - Top speed at the end of the main straight was increased by 5mph - Lap times fell by a full 3 seconds – although the rider did report “pulling the pin out” as he felt very confident on the bike during the second day These results are consistent with performance gains normally found by virtue of the combination of reduced unsprung weight and reduced rotational inertia provided by BST wheels. Even if a bike is not being used on a circuit, the same benefits of increased performance and rideability also apply to road/street use.

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I know lower weight (static) means more horsepower, can I just loose some weight to achieve the same effect as light C/f wheels?

No. Although reducing unsprung weight is always important, the added advantage of having a very low polar moment of inertia, which means they will spin up and down easily (i.e., minimum force to accelerate). The polar moment of a wheel is essentially the product of the wheel's mass elements times the location of that element from the center of the wheel (radius) squared. Since the rim of a wheel is the mass furthest from the hub, the rim mass contributes most to the polar moment of the whole wheel. Low mass carbon fiber wheels translates into a wheel with a much lower polar moment than a comparable sized aluminum/mag wheel. This is also true in transitioning a turn. Like power steering. Bumps also smooth as there is less weight for your shocks to have to compensate for, allowing for a lighter spring and shock rate.

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How does Carbon Fiber compare with Magnesium and Aluminum alloys?

Wheels manufactured from metal are either cast, forged, machined, or manufactured as a combination of the three processes. Aluminum wheels have been around for many years. They are relatively easy to manufacture and also relatively cheap, but they are heavy because of the density to strength ratio of Aluminum (how much strength you get per kilogram of Aluminum). To improve the weight you can either choose a material that is lighter or one that is stronger, or one that is lighter and stronger. Using magnesium, which is lighter but not necessarily stronger, you can improve on weight slightly. The problem with magnesium is two fold: first - its fatigue properties are poor and so are its corrosion properties, so a wheel may not last very long even if perfectly cast and machined. The second problem is worse - very often micro-porosity occurs during the casting process, which has a negative impact on both fatigue life and corrosion. So magnesium wheels can be nice and light but may not last very long, sometimes less than a racing season. This makes magnesium wheels good for racing but unattractive to the man in the street. The only solution is to find a lighter, stronger, fatigue free and corrosion free material - Carbon Fiber – which, as an engineering material is far superior to Magnesium or Aluminum alloys (see subsequent Q&A’s for its technical properties to confirm this).

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What do Motorcycle Metal/BST 16” wheels designed for Harley-Davidson® include?

Wheels are supplied with: - All internal bearings and spacers. - Sprocket/Pulley and Rotor Flanges (rear double-sided wheels) and dual flange with 2.20” rotor registers (stock 2000 ~ Current ) for direct replacement for the Touring Family.

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How much safer are Carbon Fiber wheels than standard wheels?

Carbon Fiber wheels have been in existence for some considerable time and have been proven to be safe when designed and manufactured properly and, as with any wheel, used within their design parameters. • V2: Motorcycle Metal’s HD/V2 wheels have design parameters for the maximum static weight of the motorcycle for which the wheels are designed (BlackStone Tek wheels are designed for motorcycles that weigh up to a total of 550 Kilograms wet! That translates to 1,212.542 442 017 pounds • Sport Bike: One of the parameters is the maximum static weight of the sport type motorcycle for which the wheels are designed (BlackStone Tek wheels are designed for motorcycles that weigh up to 280kg dry) and have more than adequate strength and damage tolerance for any usage within a road/street, sport or race environment. Safety is dependent on more than just strength, though, and whenever a bike becomes more easily controllable because of better dynamic characteristics, active safety is enhanced too.

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What are the physical properties of Prepreg Carbon Fiber that make it particularly suitable for wheels?

Some of the properties of Carbon Fiber composites as used in BST wheels. Material used - Carbon Fiber Prepreg in a woven and unidirectional format, embedded in a resin matrix, made from toughened epoxy. - Max structural temperature: 120 degrees C - Min structural temperature: -40 degrees C - Corrosion resistance: Totally corrosion free - Chemical resistance: Resistant to most dilatants such as acetone, benzene, thinners, - Automotive fluid resistance: Limited resistance to brake fluids and acids - Density: Approximately 1.7 kg/qdm (Aluminum 2.7, Titanium 4.5, Steel 7.9) - Damage Tolerance: Similar to 2024 Aluminum - Strength: Better than 2024 Aluminum - Stiffness: Similar to 2024 Aluminum Variable wall thicknesses can be created anywhere as needed in order to increase strength where required. Fibers are oriented in the direction of stress in order to increase strength.

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How much stronger are BST Carbon Fiber Wheels than conventional wheels?

BST Carbon Fiber wheels are comfortably over-engineered for street/road use and have undergone an intensive program of very stringent testing to verify their design and to confirm their strength and durability. In the case of a Sport Bike and not V2 (MM wheels are built much stronger): A designated test body in the UK performed the following tests and all tests were conducted on a single wheel. It is important to note that performing a ‘single wheel test’ is not usual when checking metal wheels, since due to metal fatigue behavior, a single wheel could not withstand all the tests. To allow for this weakness in metal wheels, the test regulations actually specify that using one new wheel for EACH AND EVERY test is permissible during which it is destroyed, whereas in this case a single BST wheel withstood ALL tests and was still completely serviceable afterwards. - Cornering fatigue: 100,000 cycles at 530Nm - Radial fatigue: 500,000 cycles at 5200Nm - Torsional fatigue: 100,000 cycles at 400Nm - Impact test: 337.5kg from 150mm (JWL) The front wheel was designed for a 135kg static load and the rear wheel for a 145kg static load (this translates into a bike with a total dry weight of 280kg). Modern sports bikes normally weigh between 160-220kg and race bikes rarely exceed 170kg, so these static load design parameters comfortably exceed normal conditions. The Eurotype Test Centre has tested the rear wheels where both conventional and offset versions have been subjected to cornering fatigue testing in excess of 1,000,000 (one million) cycles at 590Nm.

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Do BST wheels have TUV certification?

Yes, they have TUV certification for both their manufacturing facility and for the wheels – GSXR1000 front and rears, Ducati 916-998 series and 748 front and rears. TUV requires certification per model and the following are currently in process – Ducati 999, MV Agusta, Honda CBR1000, 954, 929 RC51 (SP1/2), others to follow.

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How much lighter are BST wheels than standard wheels?

Standard wheels are have become lighter in recent years anyway as bike manufacturers fight for magazine headlines and performance gains. However, it is still possible to make very significant weight savings. GSX-R1000 wheels have been used here as a typical example of a modern sports bike as it has wheels that are among the lightest. On older bikes, the weight savings with BST can even greater. Weight Examples quoted here include bearings, spacers, seals, sprocket, cush drive, valves, but exclude. discs & tires Standard GSX-R1000 wheel weights Front 4.360Kg Rear 7.529Kg BST with Aluminum Alloy hubs wheel weights Front 2.380Kg – weight saving 1.980Kg / 45% lighter than standard) Rear 4.638Kg – weight saving 2.891Kg / 38% lighter than standard) Total weight saving 4.871Kg

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How long have BST wheels been in development?

One of BlackStone Tek’s design engineers, Chris Adrian, has been developing Carbon Fiber wheels for nine years, some of which have been used in GPs. This new BlackStone Tek range of wheels has been under development for over 2 years. Q: What is the difference between wet lay-up and the Prepreg construction, as used in BST wheels? A: In a wet lay-up manufacturing process, the fibers are positioned in the mould dry and the resin is applied with a brush. The resin is mixed by hand and inconsistencies can be found after mixing. This is a relatively inexpensive process, but the resulting part is normally heavier and the Fibers can distort during the lamination process meaning the process is less controlled. This method does not lend itself to the Autoclave process, which cures the part under controlled heat and pressure. In the Prepreg process used to manufacture BST wheels, the resin is applied by machine onto the Fibers in a thin film. Therefore, the resin is very even and controlled. The layers are laminated by hand but can be positioned much more accurately. The parts are then cured under a high pressure and temperature environment (Autoclaved). This results in a well-compacted laminate with better properties than with wet lay-up. Laminate properties in Prepreg Carbon Fiber can be 10%- 20% better than wet lay-up at a lower weight (because less resin is used to do the same job). This Prepreg and Autoclave process is perhaps more commonly known as the process used to manufacture the exceeding strong, but light, chassis centers (often known as ‘tubs’) for Formula 1 race cars.

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How long do Carbon Fiber wheels last?

Carbon Fiber wheels originally made nine years ago by BlackStone Tek’s design engineer, using earlier and less sophisticated technology, are still running today and there have been no problems with any of them. As Carbon Fiber is a fatigue-free material, their lifespan should exceed that for wheels manufactured from alternative materials. Note that the magnesium hubs on the full race wheels are the limiting factor, as the magnesium itself should be checked for integrity every 2 years.

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How much horsepower are BST rims rated for?

BST wheels are safe up to 1900Nm torque. BlackStone Tek uses the torque measurement rather than horsepower, as it is torque that is driving the wheel. If your bike generates more than 1900Nm of torque we would like to see it, as a standard 2002 GSX-R1000 normally tests at around 99Nm…

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Any more information?

For more information about the BST range please don't hesitate to contact our sales department @ toll free: 1-866-899-5962, or send an email to howard@motorcyclemetal.com

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How do I plan my design & purchase of a standard or custom motorcycle carbon fiber wheel?

Start by choosing what tires you are going to use. What tire you are going to put on the bike! “What do you want the thing to do? Information is available from every tire manufacturer. Use it! Conceder: 1. Tire diameter & width clearance. 2. Performance - Load & speed range maximum for your application. 3. Climate conditions expected 4. Fuel & tire mileage 5. Visual appearance Remember: It is essential that you refer to your machine manufacturer’s handbook when buying and fitting replacement tire. Changes in tire size, type, and construction should not be made without first seeking advice from the machine or tire manufacturer, since fitting the wrong tire may have an adverse effect on handling, safety, and wear.

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