It's beyond amusing to read the jealous/nutter/ignoramus style comments, keep them coming, if for no other reason to provide more chuckles in another place! Especially so where those reading know of the tens of thousands of miles I've covered, frequently on heavily-laden wheels.
Worth pointing out my points are concerning rim vs disc brakes. Hydraulic over cable activation is always a good thing for ease of use and 'feel' whether on a bike or in an aircraft, not something I'm questioning (although it is questionable whether the extra complexity and cost is necessary on a bicycle, even with a small electric motor assisting).
The quoted statements above are beliefs, expectations and general sales talk rather than empirical arguments, except for the wet weather response. It's interesting to compare with the following from named individuals working for bike brake component manufrs.
Stefan Paul, Magura Bicycle Products Manager (Germany)
Joel Richardson, Hayes Brakes Product Manager (U.S.)
Magura: "Fade on disc brakes is caused either by glazing pads (the friction coefficient is decreasing, requiring much more hand force to achieve the same brake force) and/or by overheating/boiling of hydraulic fluid, no matter if DOT or mineral oil, leading to spongy feeling and even to the possibility of a full loss of brake power.
Boiling oil is even worse, because the brake can fail completely. This can be caused by constant dragging and/or steep gradients... DOT fluid has a higher boiling point than mineral oil, but mineral oil will keep the boiling point for ever, whereas DOT attracts water over time, even through seals (and its boiling point) will decrease over time and will be worse than with mineral oil.
Having big heat dissipating surfaces is good. Small compact surfaces generate heat build up.
Hydraulic rim brakes are lighter than disc brakes if you look at the complete system. The brakes itself might be equal, but forks and frames for disc brakes have to be beefier and made stiffer to take the loads from disc brakes with their asymmetrical force input. The system of road frame and fork for discs is minimum 500gr heavier than for rim brakes. Weight on disc brakes depends also a lot on the rotor size, the bigger the rotor, the more weight.
In order to achieve high heat loads on disc brakes, especially on longer, steeper descents, bigger rotors are neccessary, increasing the weight additionally. Rim brakes are more aerodynamic than disc brakes, they can be hidden in the same shape as frame and fork, Disc brake calipers and rotors always protrude the shape of frame and fork.
With rim brakes you already have the biggest possible rotor on a wheel: the rim!
Rim brakes don’t suffer from heat build up/overheating on the hydraulic system, as the distance friction partners (rim/pad) is really far away from the hydraulic piston, so no expansion chamber is even neccessary."
Hayes: "What we found with road bikes was that you can generate incredible heat and forces... You have tiny little calipers with very little thermal mass. And they have tiny little pistons that require very little fluid volume. Then you have tiny rotors with virtually no mass that can’t dissipate heat. When you whittle everything down to a super lightweight package, the only place for all that heat to go is the hydraulic fluid, and you can boil it in no time at all. When the fluid boils, it happens instantaneously and it happens right behind the brake pads. As soon as that happens, it introduces air into the system."
Worth pointing out my points are concerning rim vs disc brakes. Hydraulic over cable activation is always a good thing for ease of use and 'feel' whether on a bike or in an aircraft, not something I'm questioning (although it is questionable whether the extra complexity and cost is necessary on a bicycle, even with a small electric motor assisting).
The quoted statements above are beliefs, expectations and general sales talk rather than empirical arguments, except for the wet weather response. It's interesting to compare with the following from named individuals working for bike brake component manufrs.
Stefan Paul, Magura Bicycle Products Manager (Germany)
Joel Richardson, Hayes Brakes Product Manager (U.S.)
Magura: "Fade on disc brakes is caused either by glazing pads (the friction coefficient is decreasing, requiring much more hand force to achieve the same brake force) and/or by overheating/boiling of hydraulic fluid, no matter if DOT or mineral oil, leading to spongy feeling and even to the possibility of a full loss of brake power.
Boiling oil is even worse, because the brake can fail completely. This can be caused by constant dragging and/or steep gradients... DOT fluid has a higher boiling point than mineral oil, but mineral oil will keep the boiling point for ever, whereas DOT attracts water over time, even through seals (and its boiling point) will decrease over time and will be worse than with mineral oil.
Having big heat dissipating surfaces is good. Small compact surfaces generate heat build up.
Hydraulic rim brakes are lighter than disc brakes if you look at the complete system. The brakes itself might be equal, but forks and frames for disc brakes have to be beefier and made stiffer to take the loads from disc brakes with their asymmetrical force input. The system of road frame and fork for discs is minimum 500gr heavier than for rim brakes. Weight on disc brakes depends also a lot on the rotor size, the bigger the rotor, the more weight.
In order to achieve high heat loads on disc brakes, especially on longer, steeper descents, bigger rotors are neccessary, increasing the weight additionally. Rim brakes are more aerodynamic than disc brakes, they can be hidden in the same shape as frame and fork, Disc brake calipers and rotors always protrude the shape of frame and fork.
With rim brakes you already have the biggest possible rotor on a wheel: the rim!
Rim brakes don’t suffer from heat build up/overheating on the hydraulic system, as the distance friction partners (rim/pad) is really far away from the hydraulic piston, so no expansion chamber is even neccessary."
Hayes: "What we found with road bikes was that you can generate incredible heat and forces... You have tiny little calipers with very little thermal mass. And they have tiny little pistons that require very little fluid volume. Then you have tiny rotors with virtually no mass that can’t dissipate heat. When you whittle everything down to a super lightweight package, the only place for all that heat to go is the hydraulic fluid, and you can boil it in no time at all. When the fluid boils, it happens instantaneously and it happens right behind the brake pads. As soon as that happens, it introduces air into the system."
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