When an e-bike's pedal assist stops working, cuts out, surges or comes in late, the fault is usually in one of five places: the pedal assist or torque sensor, the speed sensor and its wheel magnet, a brake cutoff switch, the wiring, or the controller. We repair all of them at every Wilson's shop, on any brand of e-bike: pedal assist and torque sensor repair from $35, speed sensor and magnet from $35, parts and labor included. Looking it over and telling you what we find is always free.
Pedal assist is a chain of parts that all have to agree before the motor helps you. One loose plug or one dead sensor breaks the chain, and the e-bike rides like a heavy pedal bicycle. Below is how the system works, what each repair costs, and what our technicians check for each symptom.
How pedal assist decides when to help
Every pedal assist system answers two questions many times a second: are you pedaling, and how fast is the e-bike going? Different parts answer them:
- Cadence sensor: a ring of magnets at the crank and a small sensor beside it. It tells the controller that the pedals are turning, and the motor adds a set amount of power for the assist level you picked.
- Torque sensor: sits in the bottom bracket or at the rear axle and measures how hard you push on the pedals. The motor adds power in proportion, which feels smoother and more natural, especially from a standstill and on hills.
- Speed sensor and magnet: a sensor on the frame reads a magnet on the rear wheel or disc, so the controller knows the road speed and can stop assisting at the e-bike's class limit.
- Brake cutoff switches: in the brake levers. When either lever moves, the motor stops, so a stuck switch can kill assist.
- Controller and display: the controller reads all of the above and drives the motor; the display sets the assist level and shows fault codes.
How much does pedal assist repair cost?
Each price is the starting price for that job, parts and labor included:
| Job | From |
|---|---|
| Simple inspection, any brand, any issue | Free |
| Full diagnosis with disassembly or test equipment | $30, waived on repairs over $100 |
| Pedal assist and torque sensor | $35 |
| Speed sensor and magnet | $35 |
| Brake cutoff switch | $35 |
| Wiring harness and connector repair | $35 |
| Error code fix | $35 |
| Controller replacement | $35 |
| Bottom bracket and crank service | $35 |
| Dashboard and display repair | $100 |
| Hall sensor and phase wire repair | $100 |
| Motor repair (hub and mid-drive) | $100 |
| Mid-drive motor replacement | $300 |
The final price depends on your e-bike and the part it needs. Full list: how much e-bike repair costs.
What we check, symptom by symptom
Pedal assist doesn't come on at all
We start with the brake cutoff switches, because a lever switch stuck in the "braking" position stops the motor and looks exactly like a dead sensor. Then we test the pedal assist or torque sensor signal, the speed sensor, the connectors between them and the controller, and the assist setting on the display. If the throttle works but assist doesn't, the motor and battery are fine and the fault is on the sensor side.
Assist cuts in and out
Intermittent assist is usually a connection: a plug that has worked loose, a wire chafed where it runs past the head tube or the battery mount, or water in a connector. We test each connector under movement, and check the speed sensor gap, because a sensor that has been knocked away from its magnet only reads some of the time.
Assist surges, or comes in late
On a cadence sensor, a late start often means the magnet ring has slipped or cracked, so the sensor misses pulses. On a torque sensor, surging can mean the sensor needs calibrating or is failing. We read the sensor output while the cranks turn, and compare it with what the controller does.
The speed reads zero or jumps around
The speed sensor and the wheel magnet are the first suspects: a magnet that has moved on the spoke or disc, a cracked sensor, or a cable damaged when the wheel came out for a flat. Many controllers cut assist when they lose the speed signal, so a speed fault often shows up as an assist fault. Speed sensor and magnet repair starts at $35.
An error code after a sensor fault
We read the code against that model's fault list, then test the part it points to rather than replacing parts on a guess. Fixing the fault behind an error code starts at $35; looking it over is free.
Clicking or creaking from the cranks, with weak assist
On a mid-drive or a bottom-bracket torque sensor, wear in the bottom bracket or a loose crank can upset the reading as well as make noise. We check the crank arms, the bottom bracket bearings and the sensor together. Bottom bracket and crank service starts at $35.
After a fall, a crash or riding in heavy rain
A fall can push the speed sensor out of line or crack the cadence magnet ring; heavy rain can get into the sensor plugs. We open up the connectors along the frame and test each sensor. Water damage starts at $50 and crash damage at $30.
Cadence sensor or torque sensor: does it change the repair?
It changes the part, not the process. A cadence sensor is the simpler, cheaper part. A torque sensor is more precise, so it is more often matched to a particular motor and controller, and some are built into the bottom bracket or the rear axle. We replace a sensor with one that works with your controller, and test the whole chain afterwards: sensor, speed signal, brake cutoffs and assist levels.
Several e-bikes we sell use torque sensors: the Hiboy EX9 has Hiboy's first dual-sided torque sensor, the Hiboy EX11 pairs a torque sensor with a 90 Nm motor, and the Segway Xafari regulates its 12 assist levels with torque and gyroscope sensors. If you are choosing between the two types, see the best electric bikes of 2026 and e-bike classes explained.
Is pedal assist covered by the warranty?
A sensor, controller or display that fails from a manufacturing defect can be covered: 3 years on Wilson's-designed rides and 1 year on every other brand we carry, with Wilson's handling the claim. Damage from a crash, water, misuse or an unauthorized repair is excluded. See our warranty policy. Bought your e-bike somewhere else? We still repair it, wherever you bought it.
Where to get e-bike pedal assist repaired
- Flushing: 35-23 Farrington St, Flushing, NY 11354
- Elmhurst: 82-15 Queens Blvd, Elmhurst, NY 11373
- Brooklyn: 268 Richardson St, Brooklyn, NY 11222
- Long Island City: 41-13 31st Ave, Long Island City, NY 11103
- San Francisco: 360 11th St, San Francisco, CA 94103
- Miami: 2235 NW 20th St, Miami, FL 33142 (walk-ins)
Walk in at any shop, no appointment needed, or book a repair at our New York and San Francisco shops. Express service runs at every shop. Text or call (516) 300-0944. For everything else on your e-bike, see e-bike repair, chain and drivetrain repair and display repair.
Frequently asked questions
Why is my e-bike pedal assist not working?
The common causes are a brake cutoff switch stuck on, a speed sensor knocked away from its magnet, a failed pedal assist or torque sensor, a loose or wet connector, or a controller fault. We test them in that order.
How much does it cost to fix e-bike pedal assist?
Pedal assist and torque sensor repair starts from $35, and a speed sensor and magnet from $35, parts and labor included. A simple inspection is free.
Can a brake lever stop pedal assist working?
Yes. If a brake cutoff switch reads as "braking" all the time, the controller cuts the motor. We replace a switch from $35.
Why does my e-bike throttle work but not the pedal assist?
Because the throttle doesn't need the pedal or speed sensors. When the throttle works, the battery, controller and motor are usually fine, and the fault is in the sensors or their wiring.
Can you replace a torque sensor?
Yes. Pedal assist and torque sensor repair starts from $35; the final price depends on the sensor your e-bike uses and where it is fitted.
Do you repair pedal assist on e-bikes you didn't sell?
Yes. Any brand, any issue, wherever you bought it, at every Wilson's shop.
Sources: Wilson's product pages for the Hiboy EX9, Hiboy EX11 and Segway Xafari, and the Wilson's warranty policy, read November 2026. Repair prices: Wilson's price list.
