Analyzing The Peculiarities Of Shimano Centerlock Rotors

All Shimano Centerlock rotors have the same spline architecture and vary only in diameter (e.g., 180mm, 203mm…etc.). Thus, you can use any Shimano Centerlock rotor that fits your bike. If you want to upgrade to larger rotors, you will need the appropriate post-mount adapter.

Requirements For Rotor Compatability

The three major conditions that a rotor must comply with to fit in a brake system are:

  • The rotor has to be compatible with the mount that the hub uses. (Centerlock in this case; the other method uses 6 bolts).
  • The rotor has to be of the right diameter (not too small, not too big).
  • The rotor has to be compatible with the brake pads’ material (resin or metal).

Rotor Mounting Methods

All other parameters are irrelevant if a rotor cannot be installed on a wheel’s hub.

For a Centerlock rotor to be compatible with your bike, you need Centerlock-ready hubs (the brand is irrelevant).

Centerlock hubs have splines on which the rotor slides. Then, the rotor is secured with an internally or externally notched lockring that threads onto the hub.

All Centerlock hubs and rotors are compatible from the perspective of the splines. However, the lockrings that you need differ. If you have a 12mm thru-axle, you can work with an internally notched one; if you have a 15mm thru-axle, you will need an externally notched model.

Rotor Diameter

The diameter of the rotor has to be correct for the brake setup. If the rotor is too small (e.g., 140mm instead of 180mm), it will still fit, but parts of the brake pad will never come in contact with it.

As a result, those sections will remain new while the others wear down and get smaller.

Eventually, the sections that aren’t in contact with the rotor will touch each other and prevent the rest of the pad from grabbing the rotor. This phenomenon is known as brake pad overhang and causes a tremendous loss of stopping power.

If the rotor is too large, it either won’t fit into the caliper at all or will rub severely.

You can switch to larger rotors with the help of an adapter.

The adapter that you need depends on your current rotor size and the caliper mounts.

The three main caliper mounts are:

IS mounts

International Standard (IS). The brake caliper is attached to the frame and fork via bolts screwing perpendicularly to the mount. This is an older standard, and you will not find it on modern suspension forks.

Post Mount

Post Mount (PM). This is the most common disc brake mount. The caliper is mounted via bolts going directly into the mount.

Flat mount (FM). This is a fairly new disc mount common for road bikes. The mounts are very slick and discrete. Flat mounts are limited to 160mm rotors.

To transition to larger rotors, you need an adapter matching the mounts and increasing the distance by the difference between the old and new rotors.

For example, if you have 160mm Post Mount rotors, you need a +20mm Post-Mount adapter to transition to 180mm rotors.

Brake Pad Material and Rotor Compatability

Based on their material, brake pads are split into two categories:

  • Organic/Resin
  • Metal/Sintered

Most rotors can operate with both types. One exception would be Shimano’s entry-level rotors which are softer and labeled as “resin only”. Using them with metal pads would cause premature wear.

If a resin-only rotor is used with metal/sintered pads, it will wear down faster and may even warp. Warped rotors aren’t safe because they have irregularities hurting the stopping power of the bike.

If you’re going to switch from one type to the other, it’s recommended to softly sand the rotor, thoroughly clean it, and bed the pads.

Below is a list of Shimano rotors labeled as resin-only:

Shimano SM-RT30 Center-Lock182g
Shimano RT10M 211g7.44oz180mm
Shimano SM-RT70121g
Shimano Deore SM-RT54-S 162g5.71oz180mm
Shimano Tourney TX SM-RT10211g7.44oz180mm
Shimano Altus SM-RT10-M211g7.44oz180mm
Shimano SM-RT56132g
Average: 186.5 grams (6.58oz)
Shimano Centerlock Resin Only Rotors

Frequently Asked Questions About Centerlock Rotors

Can I use Shimano Centerlock rotors with non-Shimano Centerlock hubs?

Yes. If a hub is labeled as Centerlock, it has the architecture/interface to accept Centerlock rotors from any brand. Make sure to choose the correct rotor size and lockring for your hub.

It’s also fine to use non-Shimano Centerlock rotors on Shimano Centerlock hubs.

What tool do I need to change a Centerlock rotor?

If you have an externally notched lockring, you will need the “bottom bracket tool”.

If you have an internally notched lockring, a cassette tool is required. Use a breaker bar or a long pipe if the lockring is tight to gain additional leverage.

Can I use a 6-bolt rotor instead of a Centerlock rotor?

You can install a 6-bolt rotor on a Centerlock hub with the help of an adapter. But you can’t install a Centerlock rotor on a 6-bolt hub.

How tight should the lockring of a Centerlock rotor be?

The usual recommendation is 40Nm. It will be labeled on the lockring. You will need a torque wrench to tighten the lockring to the specified number.

40Nm is a lot, but it’s a safety measure. If the lockring comes undone, it’s game over, so to speak.

What are the advantages and disadvantages of using a Centerlock rotor?

The main advantage is that they’re easier to install and remove because you only have to untighten the lockring rather than several bolts.

The disadvantage is that Centerlock rotors are not as common as the bolt-on versions and there are fewer models to choose from.

Are Centerlock rotors lighter?

In short, no.

The rotors themselves are about the same weight as the other models out there. The average weight of the lockring is about 8 grams. Meanwhile, the weight of an M5 bolt used to mount a bolt-on rotor to a hub is about 1.5 grams. All 6-bolts are approximately 9 grams.

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