What Are Floating Brake Discs Used For?

One of the most common questions among riders who are still relatively new to the motorcycle world is: What is the difference between fixed brake discs and floating brake discs?

Let’s break it down. To begin with, fixed brake discs are those that are directly mounted to the center of the wheel. They are most commonly found on the rear wheel of many modern motorcycles.

With floating brake discs, the braking surface is attached to a central carrier, often called the spider or inner core, which serves two purposes: one is to hold the braking track in place, and the other is to mount the assembly to the wheel itself. We explain this in more detail in this article you can read here .

The connection between the spider and the braking track in floating discs is made using safety rivets or bobbins. If you inspect them closely, you’ll notice they have a small amount of play. This axial and radial clearance allows the disc to absorb slight misalignments when the brake pads clamp down, ensuring the disc can center itself properly during braking.

Additionally, during braking the disc reaches extremely high temperatures, which causes it to expand. The floating mechanism gives the disc the freedom to adapt to that thermal expansion. These controlled movements improve braking efficiency and consistency even under intense heat.

Like all brake components, discs have a limited service life defined by wear. Each disc includes a marked minimum thickness. You can find more details here: link .

When replacing a brake disc, it is best to measure its thickness using a micrometer (Palmer screw gauge) , which offers high accuracy thanks to the Abbe principle. Alternatively, a caliper can also be used, although it is less precise.

Our recommendation is that every time you change brake pads, you should also measure disc thickness to monitor wear and anticipate replacement.

Another useful tip is to use the same type of brake pad compound throughout the disc’s lifespan— whether organic, semi-metallic, metallic, carbon, ceramic, etc.

Remember that the holes in the braking track are designed to cool the disc and remove pad debris. Just like pads, discs also wear out and must be replaced once they reach the recommended limit.

If you are looking for the exact disc model fitted to your motorcycle, you can find its reference and specifications in the NG Brakes catalog here .