Hub motor e-bike troubleshooting: direct-drive and geared hubs

This page covers e-bikes with a direct-drive or geared motor in the front or rear wheel hub, as on most direct-to-consumer e-bikes. If your bike's maker has its own troubleshooting page, start there. See also our systems overview.

Before you start

• Find your bike's manual and display. Error codes, torque values and settings come from the bike maker, the controller and the display, not the hub itself. If your display is a Bafang one, see Bafang troubleshooting.
• Power off first. Himiway says never to work on the rear wheel with the bike powered on, and to remove the battery if you can (Himiway flat tire guide).
• Know your hub type. A geared hub freewheels when you turn the wheel forward, which is normal (hall sensor test guide).

Common problems and what to check

Motor cuts out while riding

Himiway lists the usual causes and checks for its hub motor bikes (Himiway motor cutting out):

• Battery seating. Bumps can shift the battery. Take it out, clear any debris from the slot and refit it until it locks.
• Voltage sag. Under hard acceleration or on hills, voltage can drop and trigger a cutoff, more so with a cold, old or weak battery. If cutouts happen only under load and clear after you power cycle, the battery may be the cause.
• Brake sensors. A faulty or touchy brake sensor can tell the controller the brakes are on and cut power while the display stays on. Check that both levers return fully, then see check brake cutoff and throttle.
• Speed sensor. A dirty or moved magnet can cost the controller its speed signal. Himiway says its magnet should pass within 3 to 5 mm of the sensor arrow. Other bikes differ, so check your manual and see align speed sensor magnet.
• Heat. Long climbs, heavy loads and hot weather can trigger thermal protection. Himiway suggests resting the bike 15 to 30 minutes.
• Water and connectors. Moisture can corrode connector pins. See inspect and clean connectors and e-bike got wet.

More steps: motor cuts out.

Motor stutters, jerks or won't start

• Grin, a hub motor specialist, names connector problems, hall sensors, blown controller mosfets and throttles among common failures (Grin troubleshooting).
• Check the motor cable connector is fully pushed together and undamaged, and look for wet or corroded pins (Himiway motor cutting out).
• A shop can test the hall sensors with a multimeter while the wheel is turned slowly by hand (hall sensor test guide). The test needs the system powered, so leave it to a pro.
• See throttle not working and no pedal assist.

Wheel feels loose, or the axle has turned

A hub motor pushes back on its axle. Grin explains that if the dropouts can't hold it, the axle can spin, wrap and cut the motor cables, and the wheel can come out of the bike (Grin torque arms).

• Check that both axle nuts are tight and that any torque washers or torque arms are in place. Grin says wheels put back with only hand tight nuts are at high risk.
• Regenerative braking reverses the load and can slowly loosen nuts or let the axle wiggle, so check them more often if your bike has regen.
• Grin says aluminum dropouts can crack, and front forks are usually weaker than rear dropouts.

Flat tire on the motor wheel

• Photograph the axle hardware on both sides before you take anything off, and unplug the motor cable by its connector bodies, not the wires (Himiway flat tire guide).
• Put washers, torque arms and nuts back in their original places, and tighten the nuts to the maker's torque value with a torque wrench.
• Before riding, check the wheel is centered and spins normally and the brakes work, then test the motor at low power somewhere safe.
• Step by step: fix a flat on a rear hub motor wheel and e-bike flat tire.

Grinding, clicking or humming from the hub

• Bafang lists bearing failure, gear wear or failure, rotor imbalance, water inside the housing and frame resonance as causes of mechanical noise. Electrical noise usually comes from a poor match between motor and controller (Bafang FAQ).
• These need a shop. See e-bike noises.

Error codes

Codes depend on your controller and display. On Bafang systems, hub related codes include (Bafang FAQ):

• 08: hall sensor error
• 09: motor phase winding fault
• 10: motor over temperature
• 12: motor overcurrent
• 21: speed sensor fault
• 30: communication failed
• 33: brake detection circuit fault

See e-bike error codes for other systems.

Official help

• Bafang FAQ for Bafang motors and displays.
• Grin troubleshooting guides and Grin on torque arms.

When to get a pro

• A burnt smell, which Himiway says suggests a failed controller, or grinding during cutouts, which can mean stripped gears or failed bearings (Himiway motor cutting out).
• Hall sensor, phase winding or overcurrent codes, and anything inside the motor. Grin publishes workshop guides for hall sensor repair and stator removal (Grin troubleshooting). Those are shop jobs.
• A spun axle or damaged dropout.
• Controller settings. Pedalwise doesn't cover reprogramming power or speed.

Sources

• Why does my e-bike motor keep cutting out, Himiway
• How to fix a flat tire on a rear hub motor e-bike, Himiway
• Troubleshooting guides, Grin Technologies
• Torque arms, Grin Technologies
• Hall sensor testing guide, hosted by Grin Technologies
• FAQs, Bafang

Stuck after these checks? Find a shop near you.