How to Fix Brake Discs on a Bike

Braking in an integral part of mountain biking, and disc brakes are a great addition to any mountain bike. They increase your stopping power and give you more control of the bike. They're especially more effective than rim brakes in wet conditions, although the use of disk brakes leaves your disc exposed to damage on rough trails due to their positioning. Knowing how to repair brake discs can help you stay on the trail.

Instructions

Difficulty: Moderately Easy

Things You’ll Need:

Bike stand
Hex key set
Cardboard sheet or carpet strip
Thread lock liquid
Rag or small hand towel
Channel locks
Meal file

Step 1

Secure the top tube of the bike in a bike stand. Balance the bike as evenly as possible before clamping the stand on the frame. Rotate the wheel with the damaged brake disc slowly watching for wobbles and other obvious damage, taking mental notes of where these are. Loosen the quick release on the wheel. Slide the wheel gently away from the bike. Set the wheel with the disc facing upwards.

Step 2

Straighten bent brake discs by placing a rag over the damaged portion of the disc. Place the jaws of the channel locks on the rag, over the disc, and grip the disk gently. Apply pressure in the opposite direction of the bend, bending slightly past center.

Step 3

Set the wheel upright and stand over the wheel. Look at the brake disc to see if any bends are noticeable. For bends you can see, lay the wheel down with the disc facing upward. Repeat the previous step until you can see no more bends with the wheel standing.

Step 4

Fold the rag up and hold it over both sides of the brake disc. Slide the rag around the disc feeling for any potentially rough edges. Grind any rough edges down by gently rubbing a file across rough spots and nicks in the edge of the brake disc.

Step 5

Clean metal shavings and any other impurities with a rag and alcohol. Rub the disc thoroughly and let the alcohol dry completely. Place the wheel back on the bike, and tighten the quick release. Rotate the wheel slowly watching for any damaged or bent areas on the brake disc. Remove the wheel and repeat Steps 3 and 4 for discs with additional damage. Discs too damaged to repair or use, must be removed using a hex key. Place the new brake disc on the hub and dab a drop of thread-locking liquid on each bolt as you install it.

Tips & Warnings

Repair damage as you find it rather than waiting until it gets worse

Do not pinch the vice grips too tight against the brake disc as doing so can permanently damage the metal surface

Article Written By Jeremy Slaughter

Jeremy Slaughter is a tax, accounting and small business expert. After completing his master's degree in accounting at Keller Graduate School of Management, Slaughter co-founded an accounting and tax firm where writing plays a daily role.

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