The bike shakes, buzzes or hums in a certain speed range, felt through the handlebars, footpegs or seat. Vibration can come from the wheels and tyres (it follows road speed) or from the engine (it follows engine speed). The first test tells you which.
Is it safe to ride?
With care, below the speed where it happens. If the handlebars start to shake or wobble, slow down gently without braking hard and see Handlebars shake or wobble.
Quick checks first
- Check both tyre pressures.
- Look for lost balance weights on the rim (a clean mark or glue patch).
- Spin each wheel on the stand: visible wobble?
- Is anything loose: mirrors, number plate, panels, carrier?
Diagnose it step by step
1At the speed where it vibrates, pull the clutch in and let the engine idle while you coast. Does the vibration stay?
- Yes: it follows road speed, so it is wheels, tyres or chain. Go to step 2.
- No: it follows engine speed. Check engine mounts and loose parts, see New or increased engine vibration and Rattling from panels.
2Are tyre pressures correct?
- No: set them (Check tyre pressure) and test again.
- Yes: go to step 3.
3Are the tyres evenly worn, without cupping, flat spots or bulges?
- No: see Inspect tyres for wear and damage and Tyre worn into a scalloped or cupped pattern. A bulge means stop: Tyre has a bulge or cut.
- Yes: go to step 4.
4Lift each wheel. Any side play or rough spin?
- Yes: Check wheel bearings.
- No: go to step 5.
5Spoked wheels: any loose spokes? Any wheel: runout over the limit?
- Yes: Check and tighten spokes, Check a wheel for runout. K-Light 125 rim runout limit: 2.0 mm.
- No: go to step 6.
6Felt in the bars (front) or seat and pegs (rear)? Was a tyre fitted or repaired recently?
- Yes: the wheel may be out of balance. Balance a wheel.
- No: go to step 7.
7Rear: is the chain tight in places, or the sprocket worn or loose?
- Yes: Check and adjust chain slack, see Chain is tight in some places.
- No: check the brake discs (Brakes pulse or judder) and steering head bearings.
Causes, most likely first
| Cause | How to confirm | Fix |
|---|---|---|
| Wrong tyre pressure | Gauge | Set pressure |
| Wheel out of balance, lost weight | Recent tyre work, weight missing | Balance a wheel |
| Uneven or cupped tyre | Visible wear pattern | Inspect tyres |
| Loose spokes or bent rim | Tap test, runout | Spokes, runout |
| Worn wheel bearing | Play, rough spin | Wheel bearings |
| Chain tight spots, worn sprocket | Chain check | Chain slack |
| Engine-speed vibration | Stops when coasting with clutch in | Engine vibration |