The Compatibility Of 6-Bolt Rotors And Centerlock Hubs

A 6-bolt hub can be installed on a Centerlock hub only with the help of a special adapter.

The Differences Between Centerlock and Bolt-on Attachment Mechanisms

Centerlock is Shimano’s patented method of securing a disc brake rotor to a bicycle’s front or rear hub.

This mechanism operates with a special hub that has splines in it.

The rotor body slides onto the splines, and a lock ring is used to secure the rotor against the hub.

Rear Hub with Centerlock Mechanism (notice the splines on the left)
Centerlock Rotor with Grooves for the Hub’s Splines

Meanwhile, bolt-on rotors are bolted to the hub via 4 or 6 bolts (most common) going straight into the hub.

How To Install a 6-Bolt Rotor On a Centerlock Hub

This conversion requires a special adapter.

The principle of the adapter is presented in the image above.

The adapter slides onto the centerlock hub as if it’s a rotor itself. Then, the rotor is tightened to the adapter via 6 bolts. Finally, the lock ring secures the adapter (and the rotor) to the hub.

The bolts used to connect the rotor to the adapter are M5x10mm.

The lock ring is tightened with the same tool used to install and remove Shimano’s standard cassettes when the hub has quick-release wheels.

Cassette Tool

If the hub has a 15mm thru-axle, then a bottom bracket tool will be needed as the cassette one is too small.

The Advantages of Installing a Bolt-On Rotor On a Centerlock Hub

The only advantage is the ability to use a wider variety of rotors without having to replace your existing hub.

If you want a new hub, it will be necessary to relace the entire wheel and buy new spokes due to the different flange widths.

The process isn’t incredibly complicated for advanced bike mechanics, but it’s time-consuming (if you do it yourself) or pricy (if you pay someone). On the bright side, you will gain wheel-building experience that will be very helpful in the future.

That said, it’s simpler and cheaper to use an adapter.

The Downsides Of Installing a Bolt-on Rotor On a Centerlock Hub

Adapters add weight and make the system more complicated by introducing another potential point of failure.

Shimano’s SM-RTAD05 adapter weighs about 55 grams (bolts included) and can operate with rotors up to 203mm. Thus, it would add approximately 100 grams to the bike. Why 100 instead of 110? Because a lock ring has to be used even when relying on standard Centerlock-ready rotors.

100 extra grams is not a game-changer by any stretch. They make a difference if one is trying to set a world record for the lightest possible bike. But in that case, it would make more sense to use rim brakes as they are much lighter thanks to the absence of rotors, and mounting bolts.

The rotor alone could weigh 200 grams depending on the size. Meanwhile, a light rim brake is about 250 grams. (Those numbers are just guidelines as there is a multitude of factors that influence the final weight of the brake.)

Are The Adapters Safe?

In short, yes. But only if they’re of good quality and installed correctly. The installation procedure shouldn’t be taken lightly because the rotor is subject to enormous torque. If the rotor isn’t properly secured, a fall is guaranteed, especially when the failure occurs at the front of the bike.

It’s also important to use the dedicated bolts as they have a thread lock compound (e.g., Loctite blue thread locker) on them. The thread locker is an adhesive put on the threads of fasteners to prevent unwanted loosing and corrosion due to moisture and other environmental factors.

FAQ: Can You Install a Centerlock Rotor On a 6-bolt Hub?

There isn’t a way to install a Centerlock rotor on a hub designed for bolted rotors due to massive architectural incompatibilities.

If you have accidentally bought a Centerlock rotor, replace it with a bolted model. The benefit of sticking with bolt-on rotors is the larger variety of models out there.

FAQ: I am looking for new disc brake wheels. Should I get a Centerlock hub or a bolt-on version?

First, make sure that the wheels in question satisfy your riding demands. Only then analyze the rotor attachment mechanism.

For instance, if you need lightweight road bike wheels and you can only find them in a “Centerlock version” get them.

If you want heavy-duty downhill wheels and locate a decent model with bolt-on rotors, go for it.

If the models that you are analyzing are available in both versions, then I would personally go for the bolted units for the following reasons:

  • You don’t need a cassette removal tool to install or remove the rotor.
  • Larger availability of hubs and rotors

That said, some people prefer a Centerlock ecosystem as the installation/removal process is faster since you only have to remove the lock ring rather than 6 bolts (which may be very tight by the way).

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