Front rotor. I need schoolin'.

[wizbangdoodle]

This is the front rotor on my 2012 wr450. Please tell me the purpose of having it separated from the hub.

When I was messing with my bike I noticed, when holding the front brake and rocking the bike, a little play.

When looking closer, it is from these floating rings that hold the rotor to the hub.

[bikedude987]

when the rotor heats up, it expands.  This allows the rotor to absorb more heat without warping.

[wizbangdoodle]

That makes sense. Why isn't the rear rotor the same? Not enough heat?

[GuyGraham]

Its called a 'floating' disc

as said above it allows expansion with warping

It also has side to side movement so you get better alignment with the caliper

 

Its more of a sports bike thing where braking from high speed can turn the discs blue (300°C +) - its a bit OTT on a dirt bike

[FORMA MOTO]

It's so when you tap the brakes lightly, you think your steering head is loose, and it drives you crazy until you realize they are floating discs.

[wizbangdoodle]

It's so when you tap the brakes lightly, you think your steering head is loose, and it drives you crazy until you realize they are floating discs.

This is what I thought was happening at first. I thought my bearings were shot or something.

[ThumpMe]

It's so when you tap the brakes lightly, you think your steering head is loose, and it drives you crazy until you realize they are floating discs.

 

 Been there done that....... and +1 on it driving you crazy!