When the throttle on a Rad Power Bikes e-bike stops responding, the first useful question is not "which throttle should I buy?" but "does pedal assist still work?" Rad's own Help Center starts from that split, and it can save you from replacing a part that was never the problem.
Step 1: Ride it on pedal assist first
Rad's Help Center article "Throttle Not Working" says that if the throttle is not working but the Pedal Assist System (PAS) is functioning correctly, it recommends replacing the throttle and wiring harness. It also suggests swapping in the throttle from another bike, if you have one, as a test.
Our reading: if PAS works, the battery, motor and most of the controller are doing their job, so the search narrows to the throttle, its cable and the parts that can block it. If PAS is dead too, look upstream first with our connector-by-connector check for a Rad that won't turn on.
Step 2: Read the display before you unplug anything
Rad's "Error Codes - By Bike Model" page lists three codes that matter here on many of its models. In Rad's words:
- Error 17 - Throttle on Start Up. The throttle was used while the bike started, or it is stuck in the on position. Release the throttle during startup; if the code stays, check whether the throttle sticks and replace it if it does.
- Error 22 - Throttle Fault. A fault with "either the throttle body or connection": a connector that is not seated, a connector that is damaged, wet or corroded, or a faulty throttle body. Reseat first. Damaged, corroded or wet connectors mean replacing the throttle and wiring harness; a code that persists after reseating means replacing the throttle body.
- Error 25 - Brake Sensor Fault or Brake Applied at Start Up. A brake lever was held during startup, a lever has not fully returned, or what Rad calls the motor cutoff switch is faulty. Release the lever and restart, or push the lever back into its body to reset the sensor. Rad also notes that non-OEM electrical parts on the bike can trigger this code.
For every other code, see our complete Rad Power error code reference. For help reading the symptoms, our e-bike repair online page walks through a diagnosis step by step.
Step 3: Works only in some positions? Rotate it
Rad's "Throttle Position Adjustment" article says a throttle that only works in certain positions may have interference between the throttle magnet and the brake lever magnet. Its steps: turn the bike off and remove the battery; find the hump on the throttle with a wire coming out of it; loosen the throttle with a 3 mm hex key; turn the hump to the 6 o'clock position, pointing at the ground; re-tighten, reinstall the battery and test.
Step 4: Isolate the parts that can block the motor
Rad's RadRover 6 Plus throttle article adds an isolation test. With the battery out, disconnect the right brake lever, left brake lever, taillight and headlight sensor, then reinstall the battery and see if the throttle engages. If it still does not, Rad says the controller may need replacement. If it does, reconnect everything except one part, test, and repeat until the faulty part shows itself.
That article is written for the RadRover 6 Plus and points to that model's connector check guide. Layouts differ between models, so use the guide for your bike.
Step 5: If it really is the throttle
Rad's "Throttle (Twist Power Assist) Replacement Guide" shows the job on a 2020 model, using a flat head screwdriver, isopropyl alcohol, flat side cutters, 3 mm and 5 mm Allen wrenches, a torque wrench with a 3 mm bit and zip ties. The points people most often get wrong:
- Power down, remove the battery, then hold the power or MODE button again to discharge remaining power.
- Pull the throttle connector straight apart, without twisting. On reassembly, line up the internal notch, pins and outer arrows.
- Note which way the spacer faces before you slide it off. Rad calls its orientation critical.
- Torque the throttle clamp bolt to 3 Nm and do not overtighten.
Rad recommends having a professional bike mechanic do or inspect the work. Its Help Center also says you can order a replacement throttle by giving your model and account details.
Our notes, not Rad's
- Photograph every connector before you unplug it. Bent pins and green corrosion are easier to spot on a photo.
- Write down the error code and when it appears. If you have no second throttle to swap in, that is your best evidence.
- Change one thing at a time and test after each change.
Sources
Rad Power Bikes Help Center, read November 3, 2026: "Throttle Not Working" (updated 2025-04-01), "Throttle Position Adjustment for E-Bike" (2025-04-07), "Troubleshooting Throttle Issues on RadRover 6 Plus" and "Throttle (Twist Power Assist) Replacement Guide" (2025-08-19), "Error Codes - By Bike Model" (2025-09-08), "Error Code 17/22/25 Troubleshooting Steps" (2025-10-08), "How to Order a Replacement Throttle" (2025-04-08).
RideRow is an independent parts retailer and is not affiliated with, endorsed by, or sponsored by Rad Power Bikes. Rad Power Bikes and model names are trademarks of their respective owners and are used here only to identify the bikes this guide covers.