These Floating Rotors Any Good?

[d8mok]

The point of floating rotors is to allow calipers with pistons on only one side. Instead of the caliper floating, or having the caliper centred and opposed pistons, the disc itself moves.

Pretty pointless on a bicycle for all sorts of technical reasons, not least of which most bike calipers are opposed piston. Even with single pistons they can easily be set up well enough that the flex inherent in the thin bicycle rotor is sufficie to centre them with the brakes applied, and this is how most mechanical disc systems wotk.

Just a pointless exercise, unnecessary extra mass where you want it the least - rotating - and theyre prone to rattling. I'd be inclined not to bother, and indeed I do not.

Happy to be corrected but floating rotors are more about heat management and preventing warping.

They don’t move to suit alignment (or that’s isn’t the intention)

People also confuse 2 piece rotors with floating rotors too.

 

[Chopper the ex Copper]

Yes, some argue that as a factor in their favour. The jury is out on that with motorbikes, never mind with bicycle discs that have so little thermal mass.

 

[d8mok]

I’ve noticed that Hope floating rotors do cool quickly compared to other brands.

They also make nice pinging noises

 

[eric_james]

Pinging noises explain a bit more
Hope rotors were too expensive

 

[d8mok]

I always consider the full cost of ownership. I’ve had loads of Hope brakes and they outlast the competition and work flawlessly. Overall in my man maths they cost less than repeated cheaper offerings. Plus when you’ve done with them they sell for almost as much as new

 

[eric_james]

Yes I understand that mok. I don't have £90 to spend on rotors right now.
Plus I would get into trouble

 

[mdvineng]

Floating rotors allow for uniform expansion with heat and you can use an Alloy carrier to reduce unsprung weight. Not sure it's actually required on an xc bike but a downhill one probably a good idea. I had to investigate some mtb discs that used a steel/aluminium/steel sandwich construction which had melted the the Aluminium centre layer. This was a request from the legal department in a Civil case when I was a researcher in a University Dept of Materials. The user had put these on a downhill bike because they were cheaper but the brake temperature was enough to melt the Aluminium.
On racing or high power motorcycles, floating rotors are the only answer to maintain stable braking performance. Though the rattling can drive you nuts as they wear the rivets out.

 

[robfinger]

Something else to consider especially with these cheap 2-piece rotors is the size of the rivets holding them together - in my case they stuck out on the inboard side far enough to come into contact with the little tabs that you grab onto to pull the brake pads out the caliper. This was on a Hayes MX4 caliper, another cheap mechanical caliper that uses Avid Bb7/Juicy pads barely cleared them. Shouldn't be an issue with top-load calipers like older Shimano for example.