Why this happens
A wheel that is not in line with the frame scrubs sideways as it rolls, wasting energy and wearing the tyre unevenly. A dry, rusty or worn bearing adds friction and, if left, can develop play that affects stability. On an EV, both quietly reduce range and make the motor work harder.
What you need
Tools
- Centre stand or paddock stand
- Straight edge or two lengths of string
- Measuring tape or steel rule
- Torch
- Spanners to the axle nut sizes (for inspection only)
- Torque wrench
Materials
- Clean cloth
- Notebook for measurements
Before you start
- Do not open a hub motor to reach its bearings; it contains strong magnets and the motor cable, and opening it may void warranty.
- Never ride with a loose axle nut; tighten to the manufacturer's torque before riding.
- Keep fingers away from spokes, discs and the tyre when the wheel is spinning.
Step by step
- 1
Power off and support the scooter
Turn the key off and switch off the main power switch if fitted. Place the scooter on its centre stand on level ground so the front wheel is lifted, or use a suitable paddock stand. Make sure it is stable before you push or spin wheels.
- 2
Check front wheel bearing play
Hold the top and bottom of the front tyre and try to rock it side to side, at right angles to the direction of travel. You should feel no clunk or movement at the hub. Make sure you are not feeling the steering head move instead; hold the brake lever to isolate it. Any free play suggests worn bearings or a loose axle.
- 3
Spin and listen
Spin the front wheel by hand and listen closely near the hub. A healthy bearing is quiet and smooth. Grinding, rumbling, clicking or a rough feel through your fingers on the axle area indicates a worn or dry bearing. Rule out brake rub first by checking the pads.
- 4
Check the rear wheel
Lift the rear wheel if your stand allows, or check play by rocking the scooter. Rock the rear tyre side to side. On hub-motor scooters, the rear bearings are inside the motor; noise or play there needs a service centre, as the motor should not be opened at home. Note what you find.
- 5
Check alignment with a straight edge
With the handlebars straight, hold a long straight edge or a taut string against the rear tyre's sidewall at axle height on one side, and run it forward to the front tyre. Measure the gap between the string and the front tyre's sidewall at its front and rear edges. Repeat on the other side, allowing for any difference in tyre width.
Tip: Two people make this much easier: one holds the string against the rear tyre, the other measures.
- 6
Interpret the measurements
If the wheels are in line, the gaps at the front and rear of the front tyre will be equal when the handlebars point straight. A clear difference that you cannot correct by straightening the bars suggests the rear wheel is mis-set, the frame or swingarm is bent, or the forks are twisted.
- 7
Check axle nuts and adjusters
Check that the axle nuts are tight using a torque wrench set to the value in the service manual. If your scooter has chain or belt adjusters or adjustable rear axle slots, check that the marks match on both sides. If you need to change rear wheel position on a hub-motor scooter, have a service centre do it, as the motor cable must not be stressed.
- 8
Recheck and test ride
After any tightening, repeat the spin and play checks. Take a short, slow test ride in a safe place and check that the scooter runs straight with your hands lightly on the bars and that there is no new noise.
How to tell it worked
Wheels spin quietly with no play, the alignment gaps match, axle nuts are at the specified torque, and the scooter tracks straight.
Stop and call a technician if
- There is clear play or grinding in a wheel or hub-motor bearing.
- The alignment check suggests a bent frame, swingarm or fork.
- The motor phase cable at the axle shows cuts, crushing or exposed conductors.
Questions
How often should I check wheel bearings?
A quick rock-and-spin check every month or two is enough for most riders, and always after a pothole impact or riding through deep water.
Can I replace front wheel bearings myself?
It is a mechanical job that needs a bearing puller or press and the correct bearings. If you are not experienced, have a workshop do it so the new bearings are fitted squarely.