Can mechanical disc brake overheat?

Question

I'm 195cm and 95kg and today was the second time (in one year) my mechanical disc brake pads burned down and had to replace them. The guy in the service told me that mechanical disc brakes are not that good. Is it really the case, the hydraulic brakes are much better? Or I'm really doing something wrong? (I was always told that I should only use the brakes before the corners when I descend, but when I come down from the hill and it is very steep, I just can't do that..)

Answer 1

Disc brake type should not affect pad wear, but does affect how hard you can brake. Hydraulic disc brakes tend to be more powerful than mechanical disc brakes.

Both mechanical and hydraulic disc brakes can overheat, leading to rotor "glazing" where pad material is left on the rotor, causing a slick surface and leading to poor braking performance.

Two general guidelines to increase braking power and resistance to overheating are:

1. Switching from resin disc brake pads to metallic disc brake pads (more even heat distribution)
2. Larger diameter disc rotors (more surface area for cooling)

If you are satisfied with the power of your brakes as-is, I would not consider replacing the brake pads twice a year excessive, depending on the type of riding. Brake pads are a wear item and need to be replaced periodically. It is a simple service and worth learning to do yourself. I have replaced the brake pads on my mountain bike three times this year, riding in wet and dirty conditions.

Answer 2

One way in which mechanical disc brakes typically differ from hydraulic is that the mechanical discs have one pad in a fixed position and only one that moves, whereas in the hydraulic system both pads move. It is possible that in your brakes, the fixed pad is not adjusted properly and is too far from the rotor, causing substantial drag on the moving pad before the rotor moves far enough to contact the fixed pad.

This can cause excessive wear on the moving pad as well as potentially overheating that pad. It's an easy problem to diagnose by just looking at the pads and seeing if the moving side (farther from the wheel) is much more worn than the fixed side pad.

Alternatively, even if the pads do not overheat, normal wear on the fixed pad can increase the distance from the rotor to the point that overall braking power is compromised. This is easily fixed by adjusting the position of the pad as it gets worn.

Answer 3

No, hydraulics aren't better, all disc brake suffer from ridiculously low pad life.

Disc brakes have pretty crappy pad life. You may be able to extend pad life by using sintered metallic pads as opposed to using organic resin pads. However, then the rotor life suffers, being far worse with sintered metallic pads.

I am 106 kg, and have a tendency to brake hard using only the front brake. My organic resin front disc brake pads lasted only 2000 km when riding only in dry conditions. That's the worse pad life I have ever seen on any kind of brake. For example, rim brake pads last in excess of 10 000 km if riding only on dry conditions, and even 3000 km can be expected if riding in all kinds of conditions, never avoiding riding because of rain. 3000 km is the worst pad life I have ever had on rim brakes, and the 2000 km disc brake pad life is way below that.

The actuation mechanism (hydraulic vs cable) doesn't matter. The pad type is the only thing that matters. Also how much you weigh and how hard and how often you brake are variables in pad life.