MBA Brake Shootout: Shimano SLX Vs. XTR
All Shimano brakes use mineral oil to power the hydraulic system. Why? Shimano’s justification is that DOT fluid is chemically more susceptible to absorbing humidity from the air—and this absorbed moisture lowers DOT fluid’s boiling point over time. Mineral oil maintains a consistent boiling point, providing more reliable braking performance over time. When Shimano first released its hydraulic brakes years ago, there was some skepticism about not using DOT fluid, but Shimano has since silenced all mineral-oil’s detractors. Having used Shimano systems for years, we can attest to mineral oil’s consistent performance. And as mountain bikers and lovers of the planet where we ride, we can appreciate its non-toxicity.
The SLX has a sleek, black matte finish on the all-aluminum unit and offers the I-Spec EV integration system, which allows direct-mounting of Shimano shifters to the brake lever. This helps reduce weight and eliminate extra clamps from the cockpit.
Shimano’s ICE Technologies rotors are comprised of a three-layer sandwich of stainless steel, aluminum and stainless steel. The idea is that utilizing multiple materials allows for better heat dissipation. There are also optional cooling fins that attach to the pad to help pull heat from the braking surface with the goal of longer pad life and less fade.
The four-piston caliper features a dual-diameter, opposed-piston caliper design that has different sized pistons in front and in the rear. The concept is that when the lever is pulled, the smaller piston contacts the disc brake rotor first, at the entrance of the caliper, and then connects with the more powerful larger piston. This is what produces Shimano’s trademark progressive lever feel.
Field test results:
The overall power of the SLX braking system is as robust as that of any competitor on the market. The lever feel is consistent and provides great modulation. Perhaps the best feature of this affordably priced product is the toolless reach adjustment. With a simple turn of the external knob on the lever, you can change the distance between the grip and lever blade to permit precision adjustment to suit any hand size and preference, as well as make on-the-fly adjustments. Over time, this comes in handy; as brake pads wear, you can keep the lever feel exactly the way you like it with fresh pads.
For Shimano, the XTR label represents the greatest performance advantage at the lightest weight. These components are designed to compete at the highest professional level. With XTR, there are no compromises.
The finish of XTR is a semi-matte gray on the caliper and master cylinder, complemented by a black lever and clamp. The slight color variation sets the XTR apart and certainly oozes eliteness. Similar to SLX’s levers, direct-mounting of shifters is provided via the I-Spec EV feature.
XTR’s caliper features a mono-body design that is machined from a single cold-forged block of titanium to maximize rigidity, and there are four ceramic pistons. The XTR brake lever body is made of lightweight magnesium. As with the SLX, the XTR’s master cylinder is attached inline to the brake lever using an inboard design. This increases brake lever rigidity by creating an extra point of contact between the bar and the lever.
Similar to SLX, the XTR brake lever features Shimano’s Servowave design that creates a progressive feel by increasing initial pad travel so that less lever movement is needed to bring the pads into contact with the rotor. The concept is that power is multiplied through the lever stroke to provide greater braking power. And, as with SLX, XTR’s four-piston brake lever provides an external reach adjust to ensure a consistent lever-to-grip distance at all times.
Field test results:
The XTR system offers quick brake engagement. We never experienced brake fade with the XTRs. Even on the longest downhills, the brakes functioned just as smoothly at the bottom of the hill as at the top. The XTR system performed flawlessly to deliver stable braking power and excellent modulation at all times.