Source: Excerpted from a Cycling News post on its judgement of the best bicycle disc brakes available for gravel bikes. The entire post, which can be viewed by clicking HERE, includes specific system descriptions not included in this excerpt.
BATH, U.K. – Disc brakes are synonymous with gravel bikes. Beyond the superior braking power offered by a disc rotor, they also don’t limit tire clearance the way a traditional rim caliper does — yes we know cantilever brakes allow for fat tires, but they also don’t work all that well.
Whether they’re mechanical or hydraulic, disc brakes offer consistent stopping power regardless of the weather. With traction on gravel roads and singletrack more variable than what you’d find on the tarmac, being able to precisely apply power right to the limit of the available traction can be the difference between making around a dusty hairpin or ending up in the scrub on the outside of the corner.
Road Bike Disc Brakes: Choosing the Best for You
1. Brake Pads
Even with the most flash and expensive brakes, a worn-out or glazed set of brake pads can destroy braking performance and make a big show about it too. The type of pads you’re using can also have a significant effect on what happens when you grab a handful of brakes.
There are two main types of brake pads, organic/resin or metallic/sintered. Organic pads are made from a mixture of fibers which are held together with resin. These will give you more initial bite when you squeeze the brake, but they don’t manage heat as well, and can succumb to brake fade over the course of a long, steep, descent. Organic pads also do not perform as well in the wet, and wear may be accelerated in muddy conditions
Metallic or sintered pads are made of metallic particles which are heat molded together. They offer consistent performance across all weather conditions and will not fade over the course of a long descent. However sometimes, when wet/contaminated, they scream louder than a howler monkey, and they can be hard on rotors too.
With that said, we tend to prefer metallic pads in most situations.
2. Mixing and matching
When it comes to upgrading brakes, you may be limited by the rest of your drivetrain. If you have a hydraulic system, your options will be limited as far as slotting in different calipers because each uses a different hydraulic fluid, and your brakes and levers will only be designed for that type. Using mineral oil in a system designed for DOT fluid will void the warranty and likely cause damage to seals, or even a complete brake failure — more on this later.
With that said, there are a few systems like Hope’s RX4 which come in separate versions designed for mineral oil and DOT fluid.
Mechanical disc brakes allow for quite a bit more freedom with a caveat. SRAM and Shimano levers and Campy levers utilize a different cable pull ratio, so you’ll need to make sure your calipers play nice with your brake levers.
3. Mineral Oil vs DOT fluid
If you’re looking at hydraulic brakes, you must stick with the correct brake fluid, as they are not cross-compatible and can ruin your brakes and even lead to a brake failure.
Shimano and Campagnolo use Mineral oil in its brakes while SRAM opts for DOT fluid. In the context of disc brakes for bikes, the main difference is the way that they manage water, which will inevitably make its way into your brake lines and plays a role in your brakes losing feel over time.
DOT fluid absorbs this water, while Mineral oil does not — because it’s oil. When DOT fluid takes on H2O over time, it lowers the overall boiling point, leading to a spongy feeling at the lever. Mineral oil does not mix with this water (because it’s oil), it creates pockets in your brake lines and can change viscosity throughout the brake line. Mineral oil is also safe on your skin and environmentally friendly, while gloves should be worn when dealing with DOT fluid, and it will need to be disposed of according to your local guidelines.
The entire post with images can be viewed by clicking HERE.