Do mechanical disc brakes suffer from heat-induced fade?

Question

The other day I read a question about heat induced brake fade in hydraulic disc brakes caused by too much braking on long, steep descents, which is something I have also experienced when cycling in the alps. (A quite unpleasant experience, I might add.)
This made me wonder if mechanical disc brakes would suffer from the same problem. There is no fluid to start boiling, so at first thought they should be heat-fade-proof.

If so, I think an optimized disc brake system would have hydraulic activation of a short mechanical lever or wire connected to the caliper itself. 
This way the system would optimize modulation (by minimizing elasticity) while still being safe to brake for extended periods.
I realize that even with mechanical brakes, you can't brake indefinitely, as the pads, calipers and discs would overheat at some point, but if the margin is large enough to cover most practical uses, the idea might be worth exploring.

So I'd like to hear from people with mechanical disc brakes if they have experienced heat induced fade?

Nhân Lê · Accepted Answer

From my experience, the answer is no. I have been cycling across the Great Glen and have no problem with mechanical disc brake.

My bike was moderately loaded with camping equipment. So the load (including me 70 kg) was around 110 kg or 242 lbs. There were continuous downhill sections but the brake works fine, thankfully.

From a scientific stand-point, there are three types of fade

Green fade - caused by resin boiling off of new pads
Fluid fade - brake fluid boiling and system losing pressure
Pad fade - pad overheats and loses friction

Ignoring 1, 3rd cause starts to occur at much higher temperature and require time than 2nd cause (which occurs at around 120 oC for moderately contaminated mineral oil*). That is why you need to check your mineral oil before setting out on a trip.

Pad fade is the main factor in Mechanical Disc brake fade. Unless you are not braking heavily and continuously for more than 10-20 minutes, you are fine.
In number, if you are going down 20% gradient hill, braking continuously to keep your constant speed at 18 kmph (11 mph), the braking power is around 1078 Watts for 110 kg (bike+load+rider). That means, referring to **, you can safely brake
for hours, if not hundred of hours for the iceTech.

Refer

*http://www.epicbleedsolutions.com/blog/dot-brake-fluid-vs-mineral-oil/images/shell-dot-fluid-boiling-points.png

**http://cycle.shimano-eu.com/publish/content/global_cycle/en/nl/index/news_and_info/Velotech_Disc_Brake_Test.html

Paul Jawor · Answer

i recently had a problem with cable pull hydraulic assisted brakes system, i admit me and the bike weighs in at 120kgs and i was braking from 60 km/h on a steep slope, but i experienced nearly total brake failure . It was very scary , the calipers were making contact to the disc, but i was not slowing down, even using all my force in gripping the leavers it did not help. I guess i had boiled the brakes, the discs had changed color a bit and steamed when i added water, from my water bottle !!
I imagine this is Brake fade at its most dangerous. I am now trying to go back to normal cable discs brakes. I wonder if rim brakes suffer from brake fad the way discs do =!?!?!

Do mechanical disc brakes suffer from heat-induced fade?

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