Most e-bike noises fall into one of two categories, and riders routinely misdiagnose both. The first is a harmless noise that gets treated as a dying motor: a geared hub motor whining under load, a battery rattling in its housing, a fender stay buzzing at one speed. The second is a destructive noise that gets treated as "it's always done that": a bearing grinding, a brake pad worn to metal, a loose crank bolt. The difference between the two is not experience. It is a method: four questions, asked in order, which narrow almost any noise to a handful of components before you touch a tool.

Step 1 — Ask four questions

Question 1: When does it happen?

• Only when pedalling → drivetrain, bottom bracket, pedals, crank

• Only when coasting → freehub, wheel bearings, brake rub

• Only when braking → pads, rotor, caliper alignment

• Only when the motor is assisting → motor, controller, mount, speed sensor

• Only over bumps → loose hardware, battery latch, fender, rack, cables

Question 2: Where does it come from?Have someone walk beside the bike while you ride slowly, or put the bike in a stand. Front, middle, rear. Do not guess — a rear-wheel noise transmitted through an aluminum frame sounds remarkably like a bottom bracket noise.

Question 3: What is the rhythm?This is the fastest filter in the whole process:

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Question 4: Does load change it?Stand on the pedals and it stops? That points at the saddle and seatpost. It only appears when you push hard? That points at the bottom bracket, chainring bolts, or a frame joint. It appears only with a loaded rack? Check the rack bolts and the tyre clearance.

Step 2 — The noise library

Click, once per pedal revolution

Sound: a single, sharp tick that repeats with your cadence. Likely causes: pedal threads dry or slightly loose, crank bolt under-torqued, a worn bottom bracket bearing, chainring bolts, or a shoe cleat. Confirm: swap pedals if you can — it takes two minutes and eliminates half the possibilities. Then check crank bolt torque and chainring bolts. Action: fix this week. A loose crank bolt will damage the spindle if ignored.

Click, once per wheel revolution

Sound: tick, tick, tick, proportional to wheel speed, present whether or not you pedal. Likely causes: a loose spoke or one with uneven tension, the valve nut, a rotor with a slight bend, a dry wheel bearing, or the speed sensor magnet striking its pickup. Confirm: lift the wheel and spin it by hand, listening at the hub, the rim, and the caliper separately. Action: spokes and sensor gap are quick fixes; a bent rotor needs truing; a rough bearing is a shop job.

Creak under hard pedalling

Sound: a low groan or crack that appears only under torque. Likely causes, in order of frequency: dry seatpost in the frame, saddle rails, chainring bolts, quick-release or thru-axle interfaces, headset, and only then the bottom bracket. Confirm: grease the seatpost and re-test before replacing anything. It is the most common cause and the cheapest to fix. Action: fix this week. Creaks are rarely dangerous, but they hide the ones that are.

Rattle over bumps

Sound: a loose, hollow knock. Likely causes: battery moving in its housing (a very common e-bike noise), a worn latch, fender stays, rack bolts, cables inside the frame, or a loose kickstand. Confirm: ride over a rough patch with the battery removed vs fitted, if the design allows it. Action: tighten and, where appropriate, add a thin rubber shim. A battery that moves is a connector wear issue, not just a noise.

Whine that rises with assist

Sound: a smooth electric hum or gear whine. What is normal: geared hub motors whine — it is the sound of the internal planetary gears, and it is loudest at low speed under high load. Many riders hear it for the first time on a hill and assume something is failing. What is not normal: a pitch that becomes extremely high and sharp, or a whine that appears suddenly after thousands of quiet miles. Failing bearings tend to produce a very high-pitched, penetrating tone rather than a gear hum. Action: note the conditions and record it. Normal whine: observe. New, sharp, or worsening: contact support.

Grind when braking

Sound: metal on metal, often with vibration through the lever. Cause: pads worn past the friction material, or a pad that has separated from its backing. Contaminated pads more often squeal than grind. Action: stop riding. This is the one noise in this list that damages another component — grinding metal scores the rotor, turning a pad replacement into a rotor replacement.

Rumble that follows wheel speed when coasting

Sound: a low growl or roughness you can feel through the frame. Cause: wheel bearing wear, usually from water ingress or high mileage. Confirm: lift the wheel, spin it, and feel for roughness or play at the axle. Action: shop job. Do not ride on a bearing with visible play — the failure mode is a seized wheel.

Clunk under power

Sound: a single heavy knock when the motor engages. Cause: loose motor mount bolts, axle nuts, a worn freehub, or, on hub motors, a torque arm issue. Action: stop and check the axle nuts and mount bolts. A hub motor that rotates in the dropout can destroy a frame.

Squeal or rub at one specific speed

Sound: a rhythmic, high chirp that appears only around a certain speed. Cause: brake rotor contact — a slightly bent rotor, a caliper off-centre, or a pad that is not retracting fully. Action: re-centre the caliper. If the rub follows one spot on the rotor, it needs truing.

Step 3 — Triage: what can wait, what cannot

Stop riding now:

• Grinding under braking

• Any play in a wheel bearing, or a wheel that will not spin freely

• A clunk from the rear under power, with visible movement at the axle

• A burning smell, or a motor housing too hot to touch

Fix this week:

• Clicks from the crank or pedals

• Creaks under load

• A battery that rattles in its housing

• Brake rub that comes and goes

Observe, and monitor:

• Steady motor whine that has not changed

• Tyre noise

• A single rattle you have already traced to a fender stay

The judgment call is simple: noise plus heat, play, or metal particles means stop. Noise alone, with nothing loose and nothing hot, is usually a maintenance item.

Step 4 — How to record a clip that gets a fast answer

Most support tickets about noise fail because the recording is unusable. Do this instead:

1. 20–30 seconds, phone held close to the component — not from a metre away in wind.

2. Say the conditions out loud at the start: speed, assist level, pedalling or coasting, loaded or not.

3. Show the odometer and the serial number in the same clip.

4. One noise per clip. If there are two, send two.

5. Repeat the noise twice, so it is unmistakable.

That clip plus your four answers is usually enough for a support team to tell you whether it is a warranty issue, a five-minute adjustment, or a shop visit — without either side guessing.

What never to do

• Do not open the motor housing. It voids the warranty and, on a geared hub, the reassembly is not a home job.

• Do not spray lubricant into a bearing or a motor. It flushes out the grease that is still working and carries grit inward.

• Do not "ride it out". Most noises are cheap at the first sign and expensive at the third.

• Do not let anyone diagnose it from a video without hearing it under load. Noise that disappears on a stand is load-dependent, and that is diagnostic information in itself.

FAQ

Is motor whine normal on an e-bike?On geared hub motors, yes — the internal gears produce a hum that is loudest at low speed and high load. A sudden new high-pitched tone, or a whine that gets progressively sharper, is the pattern worth investigating.

Why does my e-bike click only when I pedal hard?Load-dependent clicks usually come from the crank, chainring bolts, or a frame interface rather than the motor. Start with the cheapest fix: grease the seatpost and check crank bolt torque.

Why is my e-bike battery rattling?The latch or the housing has worn or loosened. It is worth fixing even though it seems cosmetic — a battery that moves wears its connectors, and connector wear causes intermittent power faults.

Can I keep riding with a grinding brake?No. Grinding means metal-to-metal contact, which scores the rotor. Stop and replace the pads.

The noise stopped — should I still check it?Yes, if it stopped because something fell off or seated differently, you have found the problem, not solved it.

Should I grease a noise away?Grease the interfaces that are meant to be greased — seatposts, pedal threads, quick-release faces. Never grease a bearing from the outside, and never grease anything inside a motor.