How to straighten a bent brake rotor

If your brakes are rubbing you could have a bent rotor, here are a few quick tips for straightening things out

If your brakes are rubbing it could be down to a bent rotor, so here are some tips to help you identify the problem and how to go about straighten a bent rotor — if that's the cause of the issue.

Step 1

Check caliper alignment
Check caliper alignment

If your brake is rubbing, first check that the caliper is aligned with the rotor.

Loosen the calliper bolts just enough to allow you to move it from side to side. Spin the wheel, then adjust the position of the caliper by hand until it no longer rubs, or only rubs at one point of the rotor.

Tighten the bolts alternately, a little at a time, until tight.

Step 2

Is it the front or back that's rubbing?
Is it the front or back that's rubbing?

Rotor still rubbing at one point? It’ll need straightening. If it’s the back wheel that’s affected, shift onto the smallest rear sprocket, remove the chain from the cassette and hang it over the dropout. This will make it easier to identify the bend in the rotor.

Step 3

Identify where the rubbing is happening
Identify where the rubbing is happening

Spin the wheel and listen out for a rubbing sound. Stop the wheel at the point where the rotor contacts the pads. Look down through the caliper to see which pad the rotor is touching. If it’s the right pad you’ll need to bend the rotor left, and vice versa.

Step 4

A rotor truing tool is good here
A rotor truing tool is good here

Note which part of the rotor is rubbing, then rotate the wheel until the bent section is free of the caliper.

With a rotor truing tool, adjustable spanner or clean hands, pull the rotor a few millimetres in the opposite direction to the pad it was touching.

Step 5

Repeat step 4 if the rotor is still rubbing
Repeat step 4 if the rotor is still rubbing

Rotate the bent section of rotor back into the caliper and look down through the pad slot again. If the rotor is still touching the same pad, repeat step 4, but this time bend it a little further than before.

Step 6

Be careful not to overbend
Be careful not to overbend

If the rotor now touches the opposite pad, you’ve bent it too far. Repeat step 4, but this time bend the rotor more gently and in the opposite direction to before.

Repeat until it’s central between the pads.

Step 7

Listen out for any rubbing before repeating the steps
Listen out for any rubbing before repeating the steps

Spin the wheel again, listening out for any rubbing spots. If necessary, repeat steps 3 to 6. When the rotor is no longer rubbing, put the chain back on the cassette and you’re ready to ride!

What's a rotor truing tool?

Rotor truing tool
Rotor truing tool

Also known as a truing fork, this tool makes it easy to bend the disc back into shape. A (clean) adjustable spanner can be used instead. Sometimes it’s easier to straighten the rotor by hand, particularly if a large section is bent.

This article was originally published in Mountain Biking UK magazine, available on Apple Newsstand and Zinio.

Seb Stott

Technical Writer, UK
Seb is a geeky technical writer for BikeRadar, as well as MBUK and What Mountain Bike magazines. Seb's background in experimental physics allows him to pick apart what's really going on with mountain bike components. Years of racing downhill, cross-country and enduro have honed a fast and aggressive riding style, so he can really put gear to the test on the trails, too.
  • Discipline: Mountain
  • Preferred Terrain: Steep!
  • Current Bikes: Focus Sam 3.0, Kona Process 111, Specialized Enduro 29 Elite
  • Dream Bike: Mondraker Crafty with Boost 29" wheels, a 160mm fork and offset bushings for maximum slackness.
  • Beer of Choice: Buckfast ('Bucky' for short)
  • Location: Bristol, UK

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