When to Replace Mountain Bike Disk Brake Rotors?

When to Replace Mountain Bike Disc Brake Rotors?

Someday ago, the mountain bike community planned a meet-up where one of the friends asked when to replace the mountain bike disk.

In an instant, I got a little confused;

But one of the seniors answered the question.

He said;

Controlling your brakes is critical, and the finest mountain bike disc brake rotors are there to help you.

All your bikes, whether road or mountain, now have disc brakes, so it’s important to know when to replace the disc brake rotors. Having effective brakes is a must for every road bike or mountain bike.

The disc brake rotors make riding easy, so you have to apply less force if they work properly. If the discs are old and worn out, replacement of worn discs is essential for your and other people’s safety.

The steps to doing that are detailed in this blog post.

When to Replace Mountain Bike Disc Brake Rotors?

If you are worried about changing the disk brake rotors of a mountain bike, then here are a few things to keep in mind when it’s necessary or required to change them.

bike Disk Brake Rotors

1. Upgrading Disc Brake Rotors:

The only reason you want to improve the disc brakes of your mountain bike may be so that you may get new rotors.

One-piece, steel-cut, less costly rotors are made of one material while floating rotors cost more.

Here, the braking surface is steel, whereas the center carrier is aluminum. The Ice-Tech, in many rotors, uses a three-layer sandwich structure of stainless steel and aluminum, the latter of which is used because it transfers heat more effectively than steel.

The idea is that you almost get consistent performance even if your braking system heats up while in use. Brake fade is lessened via reduced heat in the braking system (a fall-off in performance on long descents).

Additionally, it lengthens pad life and can result in noisier braking.

2. Worn Out Disc Rotors:

If you’re thinking about changing the disk brake rotors of your mountain bike, then you must notice that your disk rotors got damaged or exhausted.

Since disc brake rotors often last so long, many consider them “fit and forget” parts. On the other hand, manufacturers will set a minimum thickness for their rotors.

  • When the braking surface has been worn down to 5mm, it is advised to replace the 1.8mm-thick rotors.
  • On the rotor is a notation that reads “Min.TH=1.5,” which provides this information.
  • Mountain bike rotors start with a thickness of 1.85 millimeters. However, some of its 180-millimeter rotors are 1.9 millimeters. These 1.9-millimeter rotors should be discarded after they thin to 1.55 millimeters.

Check the specifics for the rotors you choose since several companies propose various minimum thicknesses. If you could cut ham with it, you’ve waited too long for it to get to that point!

It is possible that the rotor has to be replaced if a minor step has formed between the braking surface and the remainder of the rotor; however, before doing so, we suggest taking accurate measurements of the thickness.

3. Brake Fluid Refresh:

Brake fluid is an often disregarded and performance-affecting component of your bike’s braking system. Many of us are duped into believing that brake fluid remains constant for the whole of our bike’s life.

It is not the case. Regardless of the kind your system utilizes, brake fluid degrades with time and with use.

mountain bike Disk Brake Rotor

A mushy modulation and a less responsive brake lever feel/action might result from worn brake fluid.

It’s time to do or have your technician perform a brake fluid flush if it has been more than a year since you last had one.

4. Bent Disc Brake Rotors Of Mountain Bike:

If a mountain bike’s disc brake rotor has severe bending, then it should be replaced as soon as possible.

Disc rotors are susceptible to bending if they get overheated, sustain damage in an accident, or are often subjected to excessive side pressure when driving.

A typical reason is placing a bike in the rear of your vehicle and placing anything on the brake rotor.

When a brake rotor of the mountain bike is bent, you may be able to see it plainly, but other times you may only notice it when a portion scrapes against the brake pads when the wheel is turning.

Replace a rotor if it is severely bent, particularly if the damage was sustained in a collision.

If not, you may attempt to straighten the rotor of the mountain bike. You have nothing to lose, and it’s not a complicated science.

Doing this while the wheel is still attached to your bike will be much simpler.

Locate the bent portion of the rotor by sight or running it through the brake caliper and hearing for rubbing, and then press it back in the opposite direction while being cautious not to overdo it.

5. Altering The Rotor Size Of Mountain Bike:

Generally, you should replace a disc brake rotor of the mountain bike with one of the same sizes.

However, there are rare situations when a different size makes sense (assuming your bike can support this and you have the correct adaptors).

A big rotor will slow you down faster than a tiny rotor, all other factors equal.

The 180mm or 185mm rotors used with a disc braking system were built so that consumers could choose the size that best suited their weight and intended usage.

It is suggested that 180mm rotors for mountain bikes. Focus has informed us that, in tests, it found 185mm rotors better than the more typical 180mm since they can handle heat buildup more efficiently.

It goes against the current societal tendency for smaller rotor sizes.

You have the option; however, if you ride big, start with the 180s and see how you like them.

Disk Brake Rotor


While everyone knows that brake pads must be changed regularly, rotors are rarely discussed. You need to replace the rotors of the mountain bike if the thickness is less than 180mm.

If there’s any fault in your mountain bike’s rotor disk brakes, whether worn out or bent discs, you should change them. But these are not all the possibilities for changing the brakes. Hope by reading the above article, these points got clearer in your mind.

Frequently Asked Questions (FAQs)

How Do You Know You Need New Rotors?

Rotor wear and tear extends beyond a simple change to something lighter or bigger. You’ll need a pair of calipers to gauge the thickness of your disc since many will have a minimum thickness specified anywhere on the rotor.

If the rotors don’t specify a minimum thickness, measure the thickness of the braking surface and compare it to an area where the brake pads don’t contract; if there is a discrepancy of between 0.2 and 0.3 millimeters, the rotor is worn out and has to be replaced.

If you don’t have a pair of calipers to use as a measuring tool, run a pick or a paper clip down the rotor to see if any edges at the bottom of the braking surface catch the pick.

If they do, it may be time for a new disc.

Can A Bent Rotor Be Repaired, Or Should It Be Replaced?

Rotors are extremely brittle; it only takes a little to knock one off of alignment. Using your brakes for the whole descent may also cause excessive heat that can deform discs.

Most of the time, a few minutes with a truing tool can stop a disc from pinging a brake pad as the wheel spins, but rotors may distort it irreparably.

It’s time for a fresh disc if you’ve been working on one for more than 10 minutes and it hasn’t improved.

How Long Do Disc Brake Rotors on Mountain Bikes Last?

Disc brake rotors for mountain bikes should endure for at least 1,000–3,000 miles or through two or three sets of brake pads.

This rule is impacted by weather, maintenance, and riding difficulty. When braking often and heavily when cycling downhill, brake rotors deteriorate more rapidly.

Related Articles:-

Similar Posts

Leave a Reply

Your email address will not be published. Required fields are marked *