Disc Brake Adjustment

The mechanical disc brakes that come with all ebikes by Rad Power Bikes are are a critical safety feature and keeping them well-adjusted is very important. The brakes are essentially the same as mechanical disc brakes that come on standard pedal bikes and their adjustment and maintenance should be very familiar to any certified, reputable bike shop. 

 Read through these instructions and contact Rad Power Bikes Technical Support if you have questions. If you are not confident in your ability to successfully and safely perform all steps, we recommend having the work performed by a local, certified, and reputable bike mechanic.

Notice: With a brand new bike, a small amount of rubbing and noise can occur during the break-in period of the brake pads. If the wheel spins freely or mostly free, making no or barely making any contact between the brake disc and pads, we recommend to but around 25-50 miles on the bike to allow time for the pads and rotors to break in before making the first adjustment. 

1. Gather the tools you will need: a 5 mm Allen wrench and a torque wrench.

2. Power off the bike. Ensure the bike is in the off position and use the key to remove the battery. Once removed, press and hold the “MODE” button on the LCD Display Remote until the display remains off for about two seconds (it may flash on briefly). This ensures the power is fully discharged from the bike and it is safe to work on.

3. Elevate the bike in a bike stand that can handle the weight of an ebike or hold a wheel in the air so it can spin without making contact with the ground. Spin the wheel and check for clearance between the brake pads and brake caliper.

4.a. If the wheel does not spin freely, the brakes are likely too "tight," meaning the brake pads are making contact with the brake disk when the brake lever is not applied. Move to the "Loosening the brakes" section below.

4.b. If the wheel spins freely, check the brake lever clearance at the handlebar grip. Spin the wheel and pull the corresponding brake lever to check that the brake pads contact the brake disc about halfway between the lever's neutral position and the handlebar grip. Note: The left brake lever corresponds to the front brake, and the right lever to the rear brake. 

If the brake lever touches the handlebar, or the brake pads make contact with the brake disk when the lever is closer to the handlebar than halfway between lever-neutral and the handlebar, the brake pads are too far away from the disc, or the brakes are too "loose." Move to the "Tightening the brakes" section below.

 

Tightening the brakes: decreasing the space between the brake pads and the brake disc

  • Slightly tighten loose brakes by turning the barrel adjuster counter-clockwise. Elevate and spin the wheel, then pull the brake lever to check that the brake pads contact the brake disc about halfway between the lever's neutral position and the handlebar grip. 
  • If the brake lever touches the handlebar, or the pads make contact with the brake disk too late (when the lever is closer to the handlebar than halfway between lever-neutral and the handlebar), the brake pads are still too far away from the disc, and the inner pad will need to be adjusted closer to the rotor.*
  • Adjust the inner pad. Rotate the spokes out of the way if necessary and slot a 5 mm Allen wrench through the wheel, directly into the hole in the center of the silver brake adjuster disc. Rotate the adjuster clockwise (to the right) to move the inside pad towards the disc about 1-3 clicks.
  • Test the pad clearance and braking feel. Spin the wheel and pull the corresponding brake lever to check that the brake pads contact the brake disc about halfway between the lever's neutral position and the handlebar grip.
  • Repeat as necessary.

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*Note: For the RadRover and RadMini, both front and rear brakes' inner pad adjustment will be accessible without removing the brakes from the bike. To adjust the inner pad on the rear brake of the RadCity and RadWagon, the caliper must be unbolted from the frame to adjust the pad, and then re-attached to the frame. 

 

Loosening the brakes: increasing the space between the brake pads and the brake disc

If the wheel does not spin freely, the brake pads are making contact with the brake disk when the brake lever is not applied.

If the contact between the pads and the disc is only slight, small adjustments can be made by twisting the barrel adjuster at the brake lever. Turn silver barrel adjuster knob clockwise a few turns, which will back the outer pad away from the brake disc. 

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If the spinning wheel is resisted by substantial pad-disc rubbing, the inner pad adjuster at the brake caliper requires adjustment to back the inner brake pad away from the disc.*

  • Adjust the inner pad. Rotate the spokes out of the way if necessary and slot a 5 mm Allen wrench through the wheel, directly into the hole in the center of the silver brake adjuster disc. Rotate the adjuster counter clockwise (to the left) to back the inside pad away from the disc 1-3 clicks.
  • Test the pad clearance and braking feel. Spin the wheel and check that the wheel spins freely. 
  • Repeat as necessary.

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*Note: For the RadRover and RadMini, both front and rear brakes' inner pad adjustment will be accessible without removing the brakes from the bike. To adjust the inner pad on the rear brake of the RadCity and RadWagon, the caliper must be unbolted from the frame to adjust the pad, and then re-attached to the frame.

 

Adjust the Rear Brake on the RadCity and RadWagon 

To adjust the rear brakes on the RadCity and RadWagon, unbolt the caliper from the frame (the bolts shown in the picture below), adjust the pad, and re-attach the brake to the frame. Torque these screws to 6-8 Nm.


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If that didn't fix the issue or the disk brake rotor looks like it gets twisted when the brake is squeezed, the caliper may need to be centered.

 

Adjust the Caliper Mounting Position

To do this, start by loosening the two bolts that hold the brake caliper (shown in the picture below) onto the brake adapter that’s bolted onto the bike frame. You’ll need to use the 5 mm Allen wrench included in your toolkit to do this. Once these are loose, and the brake caliper is free to wiggle around, squeeze and hold the brake lever for this caliper, up on the handlebars. While holding this down, re-tighten the 5 mm bolts. When tightening the bolts, only turn the bolt 1/4th of a rotation then switch to the other bolt. Go back and forth to evenly tighten both bolts to 6-8 Nm.  This will center the caliper over the rotor and should take care of some of the noise and rubbing.  


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NOTICE: If you do not have the experience, skill, and tools to complete brake adjustment and maintenance, Rad Power Bikes highly recommends having a certified, reputable bike mechanic complete these procedures as well as any future adjustments or tuning.  

For questions or assistance with brake adjustment procedures or for help finding a bike shop in your area that can help, contact Rad Power Bikes Technical Support by email to support@radpowerbikes.com or by phone to (800) 939-0310 x 2.