My disc brake is rubbing constantly, How do I align it?

There is nothing quite like the irritating sound of a rhythmic ching-ching-ching as you pedal along a quiet country lane. For many UK cyclists who have made the switch from traditional rim brakes to modern disc brakes, that constant rubbing sound is a frequent source of frustration. Not only is the noise enough to drive you mad on a long ride, but that tiny bit of friction is actually slowing you down and wearing out your expensive brake pads prematurely. 

In the UK, we often deal with more brake issues than our friends in sunnier climates. The combination of rain, road grit, and salt from the winter gritters can lead to pistons getting sticky or rotors warping slightly. If your wheel doesn’t spin freely, you are essentially riding with the brakes on.  

But don’t worry, aligning a disc brake is one of the most satisfying DIY jobs you can do at home, and it doesn’t require a degree in engineering. 

Why is it Rubbing? 

Before you reach for the tools, it helps to understand why the rub is happening. A disc brake system works with a very tight tolerance. The gap between your brake pads and the metal rotor is often less than a millimetre. 

The most common cause of rubbing is simply that the “caliper” (the part that holds the pads) has shifted slightly on its mount. This can happen if you have recently removed your wheel to put the bike in the car or if a bolt has vibrated loose over time. Another culprit is a warped rotor. If you lean your bike against a railing or a street sign, a small knock to that metal disc can bend it just enough to catch the pads as the wheel rotates. 

The Solution: The “Squeeze and Bolt” Technique 

For about 90% of rubbing issues, a simple realignment of the caliper will fix the problem. You will only need one tool for this: a 5mm Allen key. 

1. Loosen theCaliper: Find the two main bolts that hold the brakecaliper to the bike frame or fork. Loosen them just enough so that the caliper can move side to side when you touch it. Do not take the bolts out completely. 
2. The Magic Squeeze: Spin the wheel and then pull the brake lever hard. Hold the lever squeezed tight. This action forces the brake pads to clamp onto the rotor, which naturally pulls thecaliperinto a perfectly centred position. 
3. Tighten While Squeezing: While you are still holding that brake lever tight with one hand, use your other hand to tighten the two bolts back up. Do this gradually, alternating between the top and bottom bolt to ensure thecaliperdoesn’t twist as it tightens. 
4. The Spin Test: Release the lever and give the wheel a spin. In most cases, the rubbing will have vanished.

When the Rotor is the Issue 

Sometimes, no matter how much you align the caliper, you still hear a “tick” at one specific point in the rotation. This means your rotor is warped or worn out. If your rotor is thin, pitted, or has been badly bent in a bike rack, the best solution for your safety is a fresh start. 

A high quality replacement like the Laxzo 160mm Disc Brake Rotor is a reliable fix for this. It uses the standard 6-bolt mounting system found on the majority of UK mountain bikes and hybrids. Replacing a rotor is as simple as unscrewing the old bolts and popping the new one on.  

A fresh, perfectly flat rotor makes aligning your brakes ten times easier and restores that silent, smooth stopping power you had when the bike was brand new. 

FAQs

1.What if the brake still rubs after I align it?  

Check your quick-release skewer or thru-axle. If the wheel isn’t sitting perfectly straight in the frame “dropouts,” the disc will never align. Always ensure the wheel is fully pushed into the frame before tightening your brakes. 

2.How do I know if my rotor is worn out?  

Most rotors start at 1.8mm or 2.0mm thick. If yours has worn down to 1.5mm or looks like it has a deep “trench” where the pads hit, it is too thin.  

3.Can I use a screwdriver to bend a warped rotor back?  

You can buy a specific “truing fork” for this, but a clean adjustable spanner can work in a pinch. However, be very careful. Rotors are sensitive to oil, so never touch the braking surface with your bare hands, as the oils from your skin can cause the brakes to squeal. 

4.Why does my brake rub only when I am turning?  

This is often due to “frame flex.” On some budget or lightweight bikes, the fork or frame can flex slightly under cornering loads, pushing the rotor against the pads. If it only happens during hard turns and stops immediately after, it is usually nothing to worry about. 

5.Should I use WD40 to stop the rubbing noise?  

Absolutely not. Never let WD40 or any oil-based lubricant get near your disc brakes. It will contaminate the pads and make the bike impossible to stop.