The wheel stops turning and skids with only light pressure on the lever or pedal, or the brake grabs suddenly instead of building smoothly. A locked front wheel usually means a fall; a locked rear makes the bike slide sideways. Causes include a brake that is already partly on (drag), a grabbing drum shoe, contaminated or wrong pads, a CBS that is out of balance, worn tyres or low grip, and poor rear suspension that lets the wheel bounce off the road. This page is about the brakes locking the wheel. If the wheel is locked while you push the bike, or on an electric bike with the motor, see the related pages.
Is it safe to ride?
No. Find the cause before riding again.
Quick checks first
- Spin both wheels on the stand. Any drag?
- Check tyre pressure and tread.
- Is it only in the wet, or on gravel or sand? Locking is easier there for any bike.
- Electric bike: is the wheel locked even with the brakes released? Go to Rear wheel is locked or very hard to push.
- Does the bike have ABS, and is the ABS light on?
Diagnose it step by step
1Is the wheel hard to turn by hand with the brake released?
- Yes: the brake is dragging, so a small extra push locks it. Go to Brake drags and the wheel does not spin freely.
- No: go to step 2.
2ABS bike with the ABS light on?
- Yes: the ABS has switched off. Go to ABS warning light is on.
- No: go to step 3.
3Is it the rear wheel on a CBS bike?
- Yes: check the rear pushrod setting and pedal free play with Adjust the rear brake pedal. If still wrong, Check a combined braking system (CBS).
- No: go to step 4.
4Is it a drum brake that grabs?
- Yes: worn cam, broken return spring, or oil-soaked or glazed linings make shoes grab. Service a drum brake.
- No: go to step 5.
5Disc brake: are the pads new, the wrong type, or contaminated, or is a piston sticking?
- Yes: fit pads listed for your bike and clean the caliper with Clean a brake caliper and free the pistons.
- No: go to step 6.
6Are the tyres worn, hard, or at the wrong pressure, or does the rear bounce over bumps?
- Yes: Check tyre pressure and Check the rear shock absorbers.
- No: practise progressive braking: squeeze, do not grab, and use both brakes.
Causes, most likely first
| Cause | How to confirm | Fix |
|---|---|---|
| Brake partly on (drag) | Wheel hard to spin | Check for brake drag |
| Low grip tyres or wrong pressure | Worn tread, low pressure | Check tyre pressure |
| Grabbing drum shoes | Drum brake, uneven bite | Service a drum brake |
| CBS out of adjustment | Rear locks on CBS bike | Adjust the rear brake pedal |
| Wrong or contaminated pads | Pads not listed for bike; oily | New correct pads |
| ABS fault | ABS light on | Diagnose an ABS warning light |
| Rear shock worn | Rear bounces over bumps | Check the rear shock absorbers |