If you twist the throttle and your e-bike takes off normally, but pedalling gives you nothing — no assist, no matter how hard you push — you are not looking at a mystery. You are looking at one of the most diagnosable faults on an electric bike, and in most cases you can clear it in your driveway without buying a single part.
Here is why, and what to try, in order.
What this symptom already tells you
A working throttle is a complete electrical test that you have already run without realising it.
For the throttle to drive the motor, current has to leave the battery, pass through the controller, and reach the motor windings. If that whole chain works, then your battery, your controller, your motor, and your main wiring are all doing their jobs. Nothing in that group is your problem.
That isolates the fault to the pedal assist (PAS) circuit — the cadence sensor that watches your cranks turn, its connector, and the assist-level setting that tells the controller how much help to add. It is a short list, and four of the five items on it are free to check.
Before you touch anything
Power the bike off, remove the battery, and wait about 30 seconds. Do this before unplugging or reseating any connector. Plugging and unplugging live connectors can arc and destroy controller components — a free fault turns into an expensive one very quickly.
We also do not recommend opening, modifying, or rewiring battery packs. That is outside what any driveway repair should cover.
Fix 1 — Check that your assist level is not sitting at zero
This is the single most common cause, and it looks exactly like a dead sensor.
Many displays reset the assist level to 0 after the battery has been run down deeply. At level 0 the controller is working perfectly and simply adding nothing. Press the UP or + button until you are in level 1–3 and pedal again.
Fix 2 — Power cycle properly
Switch off, pull the battery out, wait about 15 seconds, and put it back. This clears logic glitches in the controller that a normal on/off does not. It costs nothing and resolves a meaningful share of these cases.
Fix 3 — Look at your brake levers
Almost every e-bike has a brake cutoff sensor that kills motor output the instant you touch a lever. That is a safety feature working as designed — but a lever that has not fully returned, or a sticky cutoff switch, keeps the motor silenced. Squeeze and release both levers a few times and check that each returns fully to its resting position before you go further.
Fix 4 — Reseat the cadence sensor connector and check the magnet gap
The cadence sensor sits at the crank or bottom bracket: a magnet disc that spins with your pedals, and a pickup head that counts it. Two things go wrong here, and both are mechanical.
- The connector works loose. It sits low on the frame and gets bumped constantly, especially when you pull the battery for charging. Unplug it, check the pins are clean and dry, and push it firmly back together.
- The gap drifts. The pickup head needs to sit roughly 1–3 mm from the magnet disc. Too far and it never triggers; too close and it fouls. The disc also needs to run true rather than wobble, and both surfaces should be clean and free of chain oil.
Fix the gap and the alignment and a “dead” sensor often comes straight back to life.
Fix 5 — Then, and only then, replace the sensor
If levels are set, the bike has been power cycled, the brakes are clear, and the connector and gap are both good, the sensor itself has likely failed. These are inexpensive parts and usually terminate in a common 3-pin waterproof plug.
We stock cadence sensors for several older platforms, including a multi-model pedal cadence sensor and an R1 pedal cadence sensor. If you want to confirm continuity before you order, a basic digital multimeter is the right tool for the job.
Before you order a replacement, take four photos
Fit is decided by the connector, not by the name of your bike. Photograph your display face, your display connector close-up (pin count, gender, colours), your controller label, and your motor cable connector. Those four images are what we use to confirm a part actually matches your bike — and they are worth taking before you spend money, not after.
Where we stop
RideRow sells parts and publishes installation information. We do not perform repairs, take in service work, or make house calls — installation is done by you or by a technician you choose. Modifying a bike’s electrical system may void the original manufacturer’s coverage, and raising current or voltage can push a bike outside your local legal class limits. Those decisions stay with the owner.
If your bike will not move at all — throttle included — this article is not your diagnosis; that branch starts at the battery and main connectors instead. And if you are wondering how much life is left in the pack driving all of this, our guide on how long e-bike batteries really last is a good next read.