The RadWagon E-Bike's Disc Brake Rotor Inspection and Tightening Guide

Why E-Bike Rotors Need More Attention

E-bikes are heavier. They go faster. And they put way more stress on braking components than a regular bike. If you're riding a RadWagon or any other e-bike, rotor inspection isn't optional. It's something you should be doing every few months, especially if you're commuting daily or hauling cargo.

The video below covers a RadWagon rotor inspection, but the same principles apply to every e-bike. Read on for the full checklist.

Are there strange sounds coming from your RadWagon e-bike? 🚲💨 Your disc brake rotor could be the cause! For a safe and comfortable ride, we demonstrate in this video how to inspect and tighten a loose rotor. Just solid stopping power / no more squeaks or shaking! 👍 💬 For more e-bike advice, leave a comment below and click SUBSCRIBE! 🔥 #DiscBrakes #EbikeMaintenance #radwagon 

E-Bike Rotor Inspection Checklist

1. Check Rotor Thickness

Every rotor has a minimum thickness stamped on it (usually around 1.5mm, but check yours). A new rotor is typically 1.8-2.0mm. Once it wears past the minimum, it can crack under heavy braking. This is dangerous on any bike, but on an e-bike carrying extra weight and speed, it's a serious safety issue.

Use a caliper or micrometer to measure thickness at several points around the rotor. If you don't have one, compare a new rotor to your used one. The difference in thickness is often visible to the eye when it's getting thin.

2. Check for Warping

Lift the wheel off the ground and spin it slowly. Watch the gap between the rotor and brake pads. If the rotor wobbles side to side, it's warped. Minor warps can be trued with a rotor truing tool. Severe warps mean replacement time.

On e-bikes, warping happens more often because of heat. Heavy braking on long descents (or repeated stop-and-go commuting with a loaded cargo bike) generates heat that can permanently deform a rotor.

3. Check Bolt Torque

Rotor bolts (whether 6-bolt or centerlock) can loosen over time, especially with the added vibration of a hub motor or the extra forces from e-bike braking. Grab a torque wrench and check them every month or two. For 6-bolt rotors, the standard torque is 2-4 Nm with a T25 Torx. For centerlock, it varies by manufacturer.

Signs Your Rotor Needs Replacing

• Visible grooves or scoring – Deep grooves in the braking surface mean the rotor has seen a lot of wear. Light scoring is normal.
• Below minimum thickness – Non-negotiable. Replace it.
• Persistent warping after truing – If you've tried to true it and it won't stay straight, the metal is fatigued.
• Discoloration – Blue or purple spots indicate the rotor has overheated. It may still work, but the metal structure is compromised.
• Pulsing brake feel – If you feel a rhythmic pulse when braking, the rotor is warped or the braking surface is uneven.

E-Bike Specific Considerations

A RadWagon fully loaded with kids and groceries can weigh 100+ lbs. That's serious stopping force on every brake application. We recommend 180mm or larger rotors on e-bikes, and checking pad and rotor wear twice as often as you would on a regular bike. The cost of a new rotor is nothing compared to the cost of brake failure at speed.

Need new rotors or pads for your e-bike? Shop brake pads at Loam Goat.