So that was on my road bike, not specific testing of any sort, just I'd managed to severely contaminate the front brake - and after various methods - I finally cleared them, and I happened to be fiddling with my thermal imaging camera. I would quite like to test several setups, using a specific mass, specific speed, at same ambient conditions and coming to a halt at the same point (i.e. same amount of energy dissipation) and then leave the imaging camera with a data logging mode at several points. I expect shimano have done something like this...a very quick google leaves me with little to find.
Anyway, that was on my road bike with a 140mm ice tech "freeza" disc. So it's the triple layer thing with added heatsink fins.
You can see how effective it is - the centre bore/spider still has residual heat, and the heatsink on the disc, but the braking surface has cooled significantly. Compare that to the heatsinks on the pad which have far less surface area to dissipate the heat - I'm impressed by these little discs!
Now the discs and pads are all part of a system converting kinetic energy into heat – and then trying to shed the heat to atmosphere. Passenger vehicles on everyday run of the mill vehicles have ventilated discs (the centre bit) and often cooling vents from the bumper to the discs/calipers. Move onto WRC cars and because of trying to shoehorn huge gravel tyres, low-ish speeds for venting but lots of braking, you’ve got water cooled calipers! Anyway, back to these bicycle brakes – the vented pads are all part of this system. I’d be interested in doing some studies – but life is too short. All I’ll say is the snapshot from the thermal imaging camera really impressed me. I’d also used a blowtorch on the pads (burning off contamination, a last resort, and it worked!) and the heat really did transfer through to the fins.
So yes, bigger discs for more heat dissipation, but the fins really do something effectively. The cost side of things is a different matter altogether, and whether it’s worth the cash is entirely subjective to the individual.
