The fuzz about Internal v/s External Serrated Disc Rotor

Confused about the internal v/s external serration for the disc rotor lockring ?
Here's what it means what you need to remove or install them 🙂

And then comes with both internal and external serrations!

Locking rings with both internal and external serrations are available, such as the Shimano model Y8JX98020. These lock rings have teeth on both the inside and outside.

You might be wondering why not use both 15mm and 12mm lock rings. However, as previously explained, even a 12mm lock ring with an inner serration may cause interference during installation. Therefore, this specific lock ring is used in such cases.

And... Just like the cycling world offers too many flavours and competitive innovations - there comes the AFS hubs!

For AFS hubs, overseas manufacturers like Campagnolo and Fulcrum utilize a different center lock standard called AFS (Axial Fixing System). While the rotor splines are the same as those used by Shimano, there is a difference in the lock ring attachment area.

In Shimano's center-lock standard hub, the groove for lock ring installation is on the inside. As a result, the Shimano lock ring connection features a groove on the outside to engage the inner groove.

So which type of disc lockring should I choose?

Firstly, the thickness of the bike's axle determines the serrations, with 12mm indicating inside serration and anything thicker indicating outside serration. However, for Shimano wheel hubs, the compatibility chart specifies the appropriate lockring, and an AFS hub requires a special lockring.

Next, it is important to check the lockring's thickness as it may interfere with the fork or frame depending on the wheel hub's shape. The lockring's thickness also affects compatibility with the wheel, and some wheels come with a dedicated lockring for use.