just another gosling
Join Date: Feb 2007
Location: Everett, WA
Bikes: CoMo Speedster 2003, Trek 5200, CAAD 9, Fred 2004
Mentioned: 8 Post(s)
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I've been riding with ceramic and ceramic pads for years on my road bike. Love 'em. The physics of it is very simple. You are turning potential energy into heat. That's all that any braking system does. So for the same effect, all braking systems will generate the same heat. As the operator of the system, your responsibility is to see that the braking effect you generate does not overwhelm the system's ability to rid itself of the heat.
That said, some ceramics are much better heat conductors than others, and I don't know the physical properties of the ceramic used in rim coating. Low conductance is bad, as it would slow the transfer of heat from the aluminum rim to the atmosphere. However, all ceramics seem to be very good at heat radiation, so good that a space shuttle tile can be held in the hand 10 seconds after exposure to re-entry temperatures. Given that the rim coating is so thin, I think the balance is probably a positive cooling effect.
In any case, the therapy for rim and pad heating is to use wind braking as much as possible, and to apply front and rear brakes alternately, not at the same time, when slowing on long steep descents. If lever pressure increases, stop immediately and wait for pads and rims to cool. In short, the faster you descend, the fewer brake problems.