Frequently Asked Questions . . .

 

Q: What weight are the BST wheels designed to carry?

A: Load rating of BST wheels.

BST has derived our load specification from experience in the field of motorcycle physics:
The load rating printed on the wheel stickers will reflect the maximum weight that the specific wheel is designed to carry in a static environment. We design with a safety factor of about 4 to deal with extra demands created by the dynamics involved in motorcycling.

We present the following scenarios created around the load rating for sport bike wheels:

Scenario 1
The weight distribution of a motorcycle with a rider is approximately 40% for the front wheel and 60% for the rear wheel.

Total Static Weight or TSW = Weight of bike with all fluids + weight of rider = 220Kg + 90Kg = 310 Kg

This leaves us with the following load ratings:
For Front wheel = 310Kg x 40% = 124Kg
For Rear wheel = 310Kg x 60% = 186Kg

Scenario 2
The weight distribution of a motorcycle with a rider and with one passenger, positioned in the conventional fashion, is approximately 37.5% for the front wheel and 62.5% for the rear wheel.

TSW = Weight of bike with all fluids + weight of rider + weight of passenger =220Kg + 90Kg + 90Kg =400 Kg

This leaves us with the following load ratings:
For Front wheel = 400Kg x 37.5% = 150Kg

It can clearly be seen that Scenario 2 is the worst case for both wheels, hence BST designs wheels for this scenario and total safety.

Calculation of TSW from the load specification from a wheel:

This means the following when calculating the TSW of a bike, rider and passenger using the info of a rear wheel with a load rating of 290Kg: the BST rear wheel is designed to carry 62.5% of the TSW of machine + rider + passenger.

This means that a load rating of 290 kg for the rear is 62.5% of 100% of the total static weight, converted it will then mean that it is designed for a TSW of 464 kg with 174 kg being the load rating of the associated front wheel. This is the specific calculation for the V-Rod and V-Twin wheels.

Q: How do I set up my bike for fast road riding with BST wheels - tire pressure and suspension settings?

A: For road use, use the same tire pressure that you usually use. For suspension - if the suspension is working OK for you before you put on the BST wheels, you should not have to make adjustments.

The carbon wheels make a huge difference to the smaller bikes so there are some things you need to know. If you get chatter on fast corners once you change to the carbon wheels that was not there with metal wheels, you should be able to tune it out with suspension settings, or you could add weight to the swing-arm. The reason is simple: the total weight working on the shock is a lot less and hence you are not working within the range of the rear shock. The shock works at about 5 - 10 hertz and the wheel at +- 30 hertz so the natural frequency can chase the chatter on the smaller bikes. By putting weight on the swingarm you have the same weight working on the rear shock while gaining the advantage of the much lighter rear wheel.

We have about ten 125 Hondas that run the wheels here in SA and they also tend to run lower tire pressures cold as the carbon does not transfer heat very well and they can get a bigger contact patch with lower pressure.

Q: What torque should I use when fitting the BST wheelss?

A: Use the torque as specified for the OEM wheels. As a rule this means:

M6 bolts
10Nm
M8 bolts
16Nm

Make sure the bolts of free of grease or oil, and fasten them with Locktite.

Q: Can I use tire warmers on my BST wheels?

A: Yes you can. Make sure that the warmers and regulators are operating correctly. Do NOT use enclosed tire warmers (side covers that blanket the entire wheel) as this pushes the temperature higher than the specification given on the warmers and on the BST wheels. BST wheels are designed to operate up to 80º C which is more than adequate and will work within the requirements of the tire warmer specifications. If used under normal circumstances, a tire warmer set at 90º C will warm the tire accordingly, and the wheel itself will not achieve more than 50-60º C. Carbon does not radiate the heat as quickly as metals so there is no need to over-do it with the warmers.

Q: How should I clean my BST wheels?

A: Use warm water with a mild cleaner, avoid petroleum or alcohol based products and don’t use aggressive or abrasive cleaners. A mild de-greaser will remove any oil. You can polish them with any normal polish for a painted surface. If you want to refurbish the wheels to get back the gloss and shine, then use a polish with a rubbing compound in it, and complete the process with a finishing polish. USA Distributor Motowheels uses "Plexus" to clean and "Glare" wax to protect.

Q: How should I fit the tires to the BST wheels?

A: A normal good quality shop will be able to fit the tires. Use a tire machine, and turn down the clamping force a touch. Don’t use too much mounting fluid (or soap) as this can make beading harder.

Q: How are the BST hubs fitted to the carbon part of the wheel?

A: The hubs are attached to the carbon fiber wheel using a unique fastening system combining high strength aerospace fasteners with mechanical locking mechanisms as well as high strength aerospace adhesive.

Q: Can I change the hubs on my wheels to fit a different bike or model?

A: The wheels are made specifically for a type and model of bike. Part of the manufacturing process ensures that the wheel runs absolutely true on its own hub. The hubs have a unique fastening system, and they must not be tampered with. No-one other than the BST factory may remove the hubs. So no, you cannot change the hubs.

Q: What sprocket can I use with my BST wheels?

A: The BST wheels come with a 5 bolt hole sprocket carrier - the PCD of the 5 holes is 100mm and the ID is 76mm.

Q: What do BST wheels include?

A: The BST wheels are designed to fit the same way the OEM wheels fit. They are supplied with:

  • All internal bearings, spacers and seals pre-installed
  • External spacers, where required
  • Air valves
  • Cush drive (rear conventional swing arm)
  • Sprocket carrier (rear conventional swing arm) where required – additional wheels can be purchased without a sprocket carrier for race teams etc.
  • You will need to buy a sprocket that fits the BST sprocket carrier

    • Q: How much horsepower are the rims rated for?

    A: BST wheels are safe up to 1900Nm static 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 static torque we would like to see it, as a standard 2002 GSX-R1000 normally tests at around 99Nm.

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

    A: 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: 100 degrees C
    • Min structural temperature: -40 degrees C
    • Max operating temperature: 80 degrees C
    • Corrosion resistance: Totally corrosion free
    • Chemical resistance: Resistant to most dilutants such as acetone, benzene, thinners,
    • Automotive fluid resistance: Limited resistance to brake fluids and acids
    • Density: Approximately 1.7 kg/qdm (Aluminium 2.7, Titanium 4.5, Steel 7.9)
    • Damage Tolerance: Similar to 2024 Aluminium
    • Strength: Better than 2024 Aluminium
    • Stiffness: Similar to 2024 Aluminium

    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.
    BST has a patented process for the manufacture of a monocoque (single unit) hollow spoke wheel .

    Q: What is the difference between wet lay-up and the Prepreg construction, as used in BST wheels?

    A:     In the wet lay-up process, the fibers are positioned in the mould dry and the resin is applied with a brush. The resin is mixed by hand and mistakes can be made during mixing. This is a relatively inexpensive process, but normally the part is 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 parts are then cured under a high pressure and temperature environment (Autoclave). 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 used to manufacture the exceedingly strong, but light, chassis centres (often known as ‘tubs’) for Formula 1 race cars.


    Q: How much stronger are BST Carbon fiber Wheels than conventional wheels?

    A: BST Carbon fiber wheels have undergone an intensive programme of very stringent testing to verify their design and to confirm their strength and durability.

    A designated test body in the UK performed the following tests and all tests were conducted on a single prototype wheel.

    It is important to note that this ‘single wheel test' is not usually the case when testing a metal wheel, since due to metal fatigue behaviour a single wheel would not last throughout all the tests. To allow for this weakness in metal wheels, the test regulations actually specify that one new wheel for every test is permissible, whereas in this case a single BST wheel withstood ALL tests. A sample of test results is given below, tests and forces exerted depend upon requirements of the testing body (eg TÜV) and the wheel (front or rear).

    • Cornering fatigue: 1,000,000 cycles at 530Nm
    • Radial fatigue: 3,200,000 cycles at 6082Nm
    • Torsional fatigue: 1,000,000 cycles at 890Nm
    • Impact test: 337.5kg from 150mm (JWL)

    The front wheel was designed for a 150kg static load and the rear wheel for a 250kg static load (this translates into a bike with a total dry weight of up to 400kg). Modern sports bikes normally weigh between 160-220kg and race bikes rarely exceed 170kg, so these static load design parameters comfortably exceed normal conditions.

    Q: What performance gains can I expect on my bike by changing to BST wheels?

    A: You'll gain in many ways – this is the best performance enhancing product you can buy. BSTs will make a dramatic difference that will gain you speed and responsiveness with less effort and fatigue. It'll feel like you've added a few horses to your engine – but at a very reasonable price. Best BANG per BUCK for performance …

    Extra performance:

    Low mass and lowest Moment of Inertia (click here to see our page on The Effects of Inertia) results in a lower unsprung mass; this means faster cornering, later braking, improved acceleration – in all, faster lap times. Imagine the difference you'll experience from dropping 11.2 lbs off the weight of your bike! That's the difference in weight between the standard GSXR1000 wheels and the BSTs.

    Extra Riding Fun and Rider Safety:
    The huge drop in weight means that handling improves dramatically – quicker lap times with less effort and astonishing responsiveness means less fatigue.

    Extra Safety:
    • Carbon fibre is a fatigue free material resulting in longer product life;

    • Carbon fibre composite is a very damage tolerant material. In the event that a wheel is damaged, the damage is unlikely to propagate;

    • Very low corrosion susceptibility;
      •
    Extra Cool Looks:
    Whether you are into performance or looks, this wheel attracts attention – gleaming, black, woven- look finish and “soft” styling makes a stunning addition to your motorcycle.

    The views of UK SuperBike magazine:

    "what else can you do to a bike - for that money - to make it so much faster?"

    UK sports bike magazine, SuperBike, performed an independent two day test at the Almeria circuit in Spain using a 2002 Honda CBR900RR (954) FireBlade.

    “ 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. "

    If you have any further questions relating to this test or would like more information, email the rider, Jamie Wilkins, SuperBike magazine's Road Test Editor, on: jamie_wilkins@ipcmedia.com

    Q: How does Carbon fiber compare with Magnesium and Aluminium alloys?

    A: Wheels manufactured from metal are either cast, forged, machined, or manufactured as a combination of the three processes. Aluminium 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 Aluminium (how much strength you can get for a kilogram of Aluminium). 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 the 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 material that is lighter, stronger, fatigue free and corrosion free - Carbon fiber. As an engineering material, carbon fiber is far superior to Magnesium or Aluminium alloys.

     
    Q: Do BST wheels have TUV certification?

    A:     We achieved TUV certification for the facility and for the wheels – GSXR1000 front and rears, Ducati 916-998 series and 748 front and rears. TUV requires certification per model. BST wheels passed every test. However TUV are currently writing new specifications for carbon wheels and all manufacturers will have to have their carbon wheels tested to the new specifications when this process has been completed.

    Q: How much stronger are Carbon Fiber wheels than standard wheels?


    A:     Carbon fiber wheels have been around 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. One of the parameters is the maximum static weight of the motorcycle for which the wheel is designed (BSTs are designed for motorcycles that weigh up to 280 kg dry) and have more than adequate strength and damage tolerance for any usage within road/street, sport or race environment. Safety is dependant on more than just strength and stiffness. Due to improved handling and therefore lower driver fatigue and effort, BSTs make a positive contribution towards driver safety.