Last week’s Mechanical Monday examined the 14 myths of using tubeless tires for cyclocross, offering a guide for the pros and cons of one of the best alternatives to using tubular tires. Today we move from the rubber to the rotor. With companies such as Cannondale and Ridley who have moved towards an all-disc brake lineup, the move to disc brakes in cyclocross has never been more apparent, only emphasized by the riders near or on the podium in Tabor who rode with disc brakes.

Looking to join the ever-growing legions of hydraulic disc brake users, but have questions on maintenance for the road bike systems? For today’s Mechanical Monday, we have reached out to SRAM, Shimano and TRP to ask them about some of their best practices of maintaining their hydraulic brakes on cyclocross or gravel bikes.

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1. What are the benefits of the hydraulic braking fluid you use over the alternative?

SRAM: We use DOT 5.1, which has numerous advantages. Not only does it have a very high boiling point (minimum dry boiling point of 517° F), but it is hygroscopic. As water eventually makes its way into the fluid, it is absorbed by the DOT fluid. This drops the boiling point of the fluid, but by a safe amount. Wet boiling point of DOT 5.1 (which represents roughly 2 years of use) is 374° F, still quite high. In contrast, a hydrophobic brake fluid is incapable of absorbing the water that comes into the system, so the water would stay separate and usually pool at the low end of the system. This creates an environment where, regardless of the boiling point of the brake fluid, the system can experience problems at 212° F, the boiling point of water. DOT fluid avoids that issue.

In addition to being hygroscopic, DOT fluid is tightly regulated, ensuring that every brand of fluid meets certain minimum standards. Due to its use in the automobile and motorcycle industries, it’s also widely available no matter where you are.

Shimano: Shimano is able to offer consistent performance with our braking fluid since we control the full process of our mineral oil from start to finish. This includes relying on our own testing standards. The argument for the alternative is that DOT fluid is regulated by the government, however, with our own standards, Shimano tests each batch so that the quality is consistent and reliable.

Also, Shimano mineral oil doesn’t absorb moisture from the air, and this means that the boiling point never drops. DOT fluid absorbs moisture, on the other hand, which means the control is not as consistent.

TRP: Some of the benefits of Mineral Oil over DOT fluid is that Mineral Oil is non-toxic, has a higher boiling point and is non-corrosive and non-caustic.

Tested in cyclocross conditions: SRAM Rival 22 component group with Yaw and HydroR unveiled. © Cyclocross Magazine

Tested in cyclocross conditions: SRAM’s latest HydroR caliper. © Cyclocross Magazine

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