How to fix rotor rub on your mountain bike (without losing your mind)

There’s nothing like the high-pitched whine or the quiet whomp, whomp, whomp of your brake pads rubbing against your rotor. It’s your bike taunting you; letting you know you’re wasting energy with every pedal stroke. The good news? It’s almost always an easy fix—you just have to figure out what’s causing it.

There are three main culprits when it comes to rotor rub:
A misaligned brake caliper, a bent rotor, or brake pistons that are sticking too far out

The first step is to spin the wheel and listen. If the rubbing is constant, it’s probably a caliper alignment issue. If it’s rhythmic — like a faint “whomp, whomp” sound — you’ve got a bent rotor. If you recently took a wheel off and squeezed the brake lever, your pistons could be over-extended.

If you want to be fancy about it, you can also hold a flashlight behind the caliper or use a piece of white paper to see that tiny gap between the rotor and brake pads. Spin the wheel and figure out what’s rubbing.

Pro tip: First make sure everything is tight and aligned properly. This means your through axle or quick release. If your wheel isn’t in right, that could be culprit. Also make sure your caliper is tight and your brakpads are installed properly. Check the bolts that hold your disk on too. If any of this stuff is loose, your brakes won’t work right.

How to align a brake caliper

Most brake rub comes down to simple caliper misalignment. Here’s how to fix it: Loosen the two bolts that hold the caliper to the frame. Usually, they’re a 5 mm hex bolt or a T 25 Torx. Sometimes calipers mount to an adapter rather than the frame. The two bolts you want to loosen are the two that attach the caliper to the frame or the adapter.

With these bolts loose, squeeze the brake lever. This centers the caliper naturally over the rotor.

While holding the brake lever, retighten the bolts gradually, alternating back and forth so the caliper doesn’t shift when you torque them down.

If it’s still rubbing after that, no big deal — just loosen the bolts a tiny bit and nudge the caliper by hand until it’s perfectly centred.

How to straighten a bent rotor

If your rotor is the problem, you’ll need to get a little hands-on. The easiest way to true a rotor is with a dedicated rotor truing tool, but an adjustable crescent wrench or if you’re trailside, a clean set of needle nose pliers could work. Make sure anything you’re touching the disk with is clean; you don’t want any kind of oil or grease on your calipers.

Here’s the process:
Spin the wheel slowly and find the bent spot. Identify which side is rubbing against the pads. Use the truing tool or adjustable, gently bend the rotor away from the pad. Take it slow — light pressure and small adjustments are key.

If the rotor’s badly bent (say from a crash), you might not get it perfect. Sometimes it’s smarter to just replace it instead of battling a wobbly rotor for eternity.

If the pistons are the problem

If you yanked your wheel off and accidentally squeezed the brake lever (we’ve all done it), your pistons might be sitting too far out. Here’s the fix:
Remove the wheel and use a clean plastic tire lever (or better yet, a piston press tool) to push the pistons gently back into the caliper. Reinstall the wheel and pump the brake lever a few times to reset the pads’ position. You might need to realign the caliper again after doing this, but it’s no big deal — you’re basically a brake mechanic now anyway.

The bottom line

Brake rub sucks, but it’s an easy fix if you know where to look. Nine times out of ten, it’s just a quick caliper adjustment. Even a bent rotor usually only needs a few minutes of patient tweaking. Still stuck? Sometimes a deeper issue like uneven pistons or a brake fluid bleed is to blame — and that’s when it might be time to phone a pro. But most of the time, all you need is a multi-tool, a few minutes and a little bit of patience to silence the rub and get back to riding in peace.