carbon rotors - update?

That was always going to end badly.
I'm about to start selling vented paper rotors at $100 each. Guaranteed to save precious grams from one's bike...
Then, I'll start selling tapeworm eggs packaged as a weight loss pill. I wonder how that that will turn out..

I think Antsonline had a pair. Interested to know how they went, or didn't.

Taken from Bendix's "Cohesive Friction vs Abrasive Friction", 2007.

How Friction Materials Work

The brakes convert kinetic energy of a moving vehicle into heat. The simplest way for a
brake system to absorb kinetic energy is to break chemical bonds in the rubbing surfaces of
the brake pads and rotor. This is called "abrasive friction", because the pads and rotor act as
an abrasive, pulling each other apart, wearing, and turning the pad into dust.
A more sophisticated way to absorb kinetic energy is "cohesive friction" (or adhesive
friction). Cohesive friction is used in modern non-asbestos organic (NAO) friction materials
such as Bendix General CT.

In order to use cohesive friction, pads deposit a film of friction material on the surface of the rotor. As the rotor passes between the pads, the film and the pad surface heat up and become sticky. The pads and friction film bond to each other then break apart, absorbing
energy. They bond and break apart continuously as the rotor passes between the pads.
Cohesive friction relies on the surface properties of the friction material and transfer film,
which change with temperature. A material that is sticky at 30°C might be very slippery at
150°C. This means that an adhesive friction material must use a cocktail of adhesive
ingredients to maintain the "sticky" properties over a range of temperatures.

Used under its design conditions, a cohesive friction material does not wear the rotor at all, as the rotor iron is protected by the friction film. The pads wear slowly, just enough to keep a supply of adhesive materials at the surface.
No material loss from the pads and rotors means no brake dust.
Cohesive friction is not possible at extreme temperatures, as the adhesives lose their
effectiveness when they get too hot. The only friction available at high temperatures is
abrasive, resulting in accelerated wear for pads that are not optimised for these conditions.
In frequent or sustained high temperatures, a purpose-designed high-performance friction
material should be used. In order to meet their high temperature operating requirements,
high performance materials must use abrasive friction. More abrasion means more dust.

I suspect the problem with the carbon rotors is outlined in the second paragraph where they are not able to hold a layer of pad material to provide the required cohesive friction - this is that initial "bite" you are indoicating they don't have. As mentioned, the temperature range and disc/pad material composition has a lot to do with this.
The other thing to remember is that the carbon brakes used on cars operate at extremely high temperatures due to the relatively high heat capacity/gram as compared to traditional cast iron rotors. They have a melt temperature of 3700 degrees C as compared to cast iron at 1500 degrees C.
I know this all sounds like waffle and you may think it is not at all relevant to MTB but the basic principles still apply.

@hathill from my memory of what I read on the kickstarter proposal it talked about needing to transfer pad material to the rotor to get them to work. Maybe organic pads are needed?

I used carbon floating disc brake rotors 15 years ago on r/c model cars but can't remember what the pad material was. Found the same, initial bite was reduced.

So with pads and rotors, I guess you'd say in order to get them to work properly you have to go fully SIC, mate.

Ba-doom tish