Home Getting Started What is a Rim Magnet & How to Check if Your Bike Has One

What is a Rim Magnet & How to Check if Your Bike Has One

Last updated on Jan 27, 2026

What is a Rim Magnet & How to Check if Your Bike Has One

From 2025, many Bosch-powered eBikes use a rim magnet speed sensor, and knowing whether your bike has one is crucial for choosing the correct tuning kit.

What is a Rim Magnet?

A rim magnet sensor looks like this. It's a small magnetic sensor attached to the rear wheel's valve stem. It works with a sensor in the motor to measure your wheel's rotation and calculate your speed.

Why does this matter? A lot of eBikes from 2024 onwards are fitted with these sensors. They require a specific type of tuning kit. Our plug & ride kits will not work with this sensor.

How to Check if Your Bike Has a Rim Magnet

Step 1: Look at Your Rear Wheel Valve

Check the area around your rear wheel's valve stem (where you pump air into the tyre). If you see a small black module attached to the rear valve, you have a rim magnet.

Step 2: Look inside the rear wheel tire

If you don't see a small black module on the valve, you may have an internal sensor as shown in the example on the right above. Rather than be visible on the valve stem, it's hidden within the wheel rim.

Visual Guide

Rim Magnet System:

  • Small module attached to the valve on the rear wheel (either outside or inside the rim)

  • Common on newer Bosch Powered bikes from 2024 onwards

No Rim Magnet:

  • A physical magnet will be on the rear wheel spokes

  • Or, a rotor magnet will be found near the rear cassette

  • Common on older Bosch systems and Smart System bikes pre 2024

Which Bikes Typically Have Rim Magnets?

Bikes WITH Rim Magnets:

  • Most Bosch Performance Line CX Gen 5 bikes

  • Many Bosch Performance Line CX Gen 4 bikes (from 2024)

  • Some Bosch Smart System bikes with Gen 3 motors

  • Most Bosch Performance Line SX bikes

Bikes WITHOUT Rim Magnets:

  • All older Bosch powered bikes without Smart System

Why This Matters for Tuning Kits

Using the wrong kit type will not work - the kit is designed to interact with a specific type of speed sensor.

Not Sure? Here's What to Do

  1. Take a photo of your rear wheel (near the valve) and your chainstay

  2. Send it to us - we'll confirm whether you have a rim magnet

  3. Or share your bike make, model, and year and we'll look it up for you

Need help? Contact us with photos of your rear wheel area and we'll identify the right kit for you.