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How-to guide

Universal throttle and pedal assist sensor replacements: what has to match

Replacing a thumb or twist throttle or a PAS sensor with a universal or aftermarket part: signal, plug and magnet count, class rules, and examples from parts specialists.

Last edited Nov 8, 2026 by Pedalwise team Edit History Add a subpage

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Difficulty
Moderate
Time
20 minutes for a throttle, about an hour for a PAS sensor

This guide is for replacing a broken thumb or twist throttle, or a pedal assist (PAS) sensor, with a universal or aftermarket part. These are the most swappable electrical parts on an e-bike, but the plug, the signal and the bike's class still have to match. First check it's really the part: see Throttle not working, No pedal assist and Check brake cutoff and throttle.

Remove the battery before you unplug anything. Never cut and splice wires to fit a different plug, and never bypass a brake cutoff sensor. If the new part's plug doesn't match, stop and find a shop.

When this makes sense

Use the bike maker's own throttle or sensor first. Go universal when that part is gone or the maker can't supply it, and only when the seller shows it fits your bike or kit.

Options

Thumb or twist throttle (easy, plug and play when the plug matches)

  • What it replaces: the throttle on the handlebar.
  • What must match: Grin Technologies explains that most throttles use a hall sensor, putting out about 0.8 to 0.9 volts at rest and about 3.6 to 4 volts at full (Grin, e-bike parts explained), so the signal is common but plugs vary widely between makers. Match the plug and pin count.
  • Bafang kits: California Ebike lists Bafang throttles for the BBS02, BBSHD and Ultra, with universal thumb throttles at $10 and a heavy duty left thumb throttle at $16, and the half twist versions sold out (read Nov 9, 2026).
  • Sondors and similar: Area 13 E-Bikes lists a twist throttle at $32.99 with a 6 pin waterproof plug, a direct fit for single speed Sondors and some others (read Nov 9, 2026).
  • Rad bikes: Area 13 also lists a Rad thumb throttle at $24.99 that it says fits all Rad models as far as it knows, out of stock when we read it on Nov 9, 2026.
  • Class matters: a Class 1 bike has no throttle (Bosch, three class system), so don't add one to a Class 1 bike. On a Class 2 bike the throttle stops helping at 20 mph.
  • What's involved: loosen the grip side clamp, slide the old throttle off, fit the new one, route the cable clear of the steering, and plug it in with the battery out.

Pedal assist sensor (moderate, needs a crank puller)

  • What it replaces: the cadence sensor and magnet ring at the bottom bracket.
  • What must match: Grin notes that pedal sensor signals aren't standardized, so compatibility with a given controller is hard to predict, and that a torque sensor is a different part that replaces the bottom bracket (Grin). Match the sensor type, magnet count and plug.
  • Parts and prices (read Nov 9, 2026): Area 13 E-Bikes lists a universal PAS sensor with 10 magnets at $14.99, said to work with Rad, Sondors, Area 13 and other bikes, and warns to check crank clearance first.
  • Rad's integrated sensor: Rad says all RadRunner models, the RadMission, RadTrike, RadExpand 5, RadCity 5 and RadRover 6 use an integrated PAS sensor. Its replacement guide uses a crank puller, refits the left crank bolt to 35 Nm, and asks you to have the work checked by a certified mechanic.
  • What's involved: unplug the sensor, pull the left crank, slide the old sensor off noting its direction, fit the new one, refit the crank to its stated torque, and plug in.

Setting it up

  • On KT displays, the manual's P4 setting decides whether the throttle can start the bike from a stop, and C1 sets the pedal sensor type (KT-LCD3 manual). Use the values your kit maker gives.
  • Check the brake levers still cut the motor with the new part fitted.
  • Keep the speed limit within your class: 20 mph for Class 1 and 2, 28 mph with pedal assist for Class 3.
  • Going past your e-bike class limits can make the bike illegal on public roads and bike paths in many places, voids the warranty, and adds wear on the battery, motor and brakes. A bike set up as Class 3 needs a Class 3 label.

Videos

Replace a Pedal Assist Sensor on an E-Bike from E-Bike Eric: a PAS sensor swap at the bottom bracket.
Himiway Expert: How to inspect or replace a pedal assist sensor from Himiway Bikes: a maker shows how it checks and replaces its sensor.
Thumb to Twist Throttle, Get the parts you want from CitizenCycle: swapping throttle styles at the plug.
Replacing Himiway throttle with a Thumb throttle, Tinkering Turtle from Tinkering Turtle: an owner fits a different throttle style.

When to get a pro

Get a shop if the throttle runs on by itself, the motor surges, the crank won't come off cleanly, or the plug doesn't match. A runaway throttle is a stop riding fault. See When to call a pro.

Sources

Stuck after these checks? Find a shop near you.

Need a pro?

If these steps didn't fix it, find a shop near you in our partner network. For battery or wiring trouble, look for shops marked Battery and electrical.

Talk

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