Floating Brake Rotors Vs. Solid Brake Rotors

Floating brake rotors are made from two pieces of metal instead of one solid piece. Floating brake rotors feature an outer ring that is contacted by the brake pads and an inner ring that attaches to the wheel.
Warping
Brake rotors can be subjected to extreme temperatures. Though the brake rotor is made from materials meant to withstand this temperature, rotors can and do warp. Floating rotors reduce the chances of warping as the outer ring can heat up and expand without impacting the inner ring which stays much cooler as it is not in contact with the brake pads.
Rotor Life
The constant expansion and contraction of the brake rotor will cause the rotor material to weaken and eventually fail. Floating rotors are less impacted by this heat as the outer ring is allowed to expand independent of the inner ring, giving the floating rotors a longer service life than solid rotors.
Cost
Solid brake rotors are much less expensive than floating rotors as they are much simpler to manufacture. Though more expensive to purchase than solid rotors, the longer life of floating rotors may offset their cost over the life of the bike.