Care and feeding of polyurethane wheels

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The Motorboard drive system is friction based. The two motors make direct contact with the sidewalls of the rear wheel. It is normal that after about 150 miles (or less depending on road conditions and rider weight), the sidewalls of the rear wheel will wear down, and eventually be unusable. The rear wheel and the front wheel can be swapped, but once both wheels have worn down, a new wheel must be purchased.

Sudden stops by the wheel, caused by running over small stones, will cause the motor to carve a notch out of the wheel. Check that the sidewalls are smooth and free of any notches. Sidewalls with notches or grooves can create clicking or knocking sounds. Notches are very hard on the motors and will cause significant loss of power. A tire with sidewall grooves will damage the motors.

Excessive flat spots will result in extensive vibration, and will require you to change your tire. To avoid excessive wear of your tire, avoid skidding, or locking up the wheel to stop. Tires will last somewhat longer if the hand brake is used as little as possible.

Also it is very important that the motor spindle firmly touches the wheel. If the motor is loose or not connected properly to the motor sled, then loss of power will result.

Road surfaces

The most significant factor in determining wheel wear is the road surface. Small isolated rocks are particularly hard on polyurethane wheels.

Unfinished road surfaces causes rapid wear on wheels. Avoid sandy areas, wet, frozen, oily, or unpaved surfaces. Avoid potholes and surface cracks.

Brick pavement does not seem to adversely affect the wheels.

While cleaning with alcohol is recommended for maximum traction, it has been noticed that brand new wheels have "too much" traction. Wheels can be damaged very easily within the first few days of operation. Instead I have had success allowing the wheel to get coated with a small bit of "road dirt" (dust, grime and oil), which works its way into the polyurethane. After a week or two, then I begin to clean with alcohol. The traction is reduced somewhat, causing a slight reduction in speed, but the lifetime of the wheel can be increased from 1 week to 1 year.

Overuse

It is possible to damage or crack a wheel due to hard “scrubbing” or cornering with a heavy rider. Care should be taken to prevent conditions that lead to wheel breakage. Although the bearings are rated to carry the weight of a medium car, it is possible to crack them. The clicking noise may also be the result of a cracked wheel or bearings.

Jumping curbs can cause wheels to crack or fracture. The wheels may crack near the bearings with repeated abuse.

It is also important to fight the natural tendency to position your weight over the rear wheel. This wears out the rear wheel faster and causes increased wear on the motors and transmission (possibly breaking the motors or the bolts that hold the motors to the motor sled). For best performance it is best to evenly balance your weight between the front and back wheels by placing your feet accordingly.

Water damage

Damage may also be caused by water (although I have not seen this). If the wheel is wet, then you should dry it, especially the sidewalls. Wet walls will significantly degrade performance. Also wet grime from the street may enter the motorboard housing and short out the Motor Controller.

Cleaning

The wheels are best cleaned by a small bit of alcohol. Water tends to swell the wheels.

The manual says if you see the “eraser grit” on the sidewalls, use your thumb to rub as much off as you can. Ridges should be sanded down so they don't wear unevenly and crack. Crack edges should also be sanded down so that they don't expand.

Measuring

You can use the included Tire Gauge to help you determine when the rear wheel is worn down. The rear wheel sidewalls to wear down with use. The depends on environmental factors such as dirt and sand. The cleaner the road, the longer your tires will last.

In order to function the rear wheel must have a minimum sidewall thickness of 41mm to operate.

The included Tire Gauge can be to determine if your tire meets this specificaion:

  • Check tire wall thickness
  • Tire crown, or the cross section of the tire
  • Check for flat spots on the tire, caused by using the braking system, skidding, or locking up the wheel.

Checking the sidewalls

There are two motors, one on each side of the tire, so it is important to check both sides of the tire, as they may not wear down evenly.

  • Wipe off the grey-blue rim and tire in the area you will be checking.
  • Position the Tire Gauge on the rear tire as shown in the picture to the right. The Tire Gauge sits on the plastic rim of the wheel, next to the orange tire.
  • The orange material of the sidewall must be higher (thicker) than the thickness of the Tire Gauge. If it is just level or thinner, then its time to replace the tire.

Checking the Cross Section

  • Position the Tire Gauge on the rear tire as shown. The Tire Gauge should fit snugly over the tire. The center of the tire should be very close to the gauge. The maximum gap should be less than 3 mm (1/8” ).

Checking for flat spots

  • Position the Tire Gauge on the rear tire as shown. Run the Tire Gauge along the tire, and make sure it maintains full contact with the tire. Any flat spots, bald, or skidded areas in the tire should become apparent.

Storage

The polyurethane dries out over time. When new polyurethane wheels are shipped to you, they are usually packed in plastic bubble wrap. It is important that the wheel stay enclosed in plastic to preserve its "freshness". A wheel that has been exposed to the air for six months or more is liable to crack within weeks after use.

See also

References