Lewis R2 Ultra-light Flat Mount Monoblock Brake Caliper

The Lewis R2 is an ultra-light flat mount hydraulic disc brake caliper designed for riders who want lower weight, a cleaner setup, and a more refined braking feel.

Machined from 7075-T6 aluminum bar stock, the R2 uses a one-piece monoblock CNC caliper body to improve structural rigidity while reducing unnecessary material and hardware. Compared with traditional split-body calipers, the monoblock construction uses fewer body bolts, allowing the caliper to be made lighter, smaller, and stronger.

At only approximately 63g per caliper, excluding brake pads and fittings, the R2 is a strong upgrade choice for lightweight road bikes, climbing builds, premium gravel bikes, and custom performance builds.

Key Features

One-piece Monoblock CNC Construction

The R2 caliper is CNC-machined from a single piece of 7075-T6 aluminum. This monoblock design creates a stronger and more rigid caliper body compared with conventional two-piece calipers.

By reducing the number of body bolts and connection points, Lewis is able to remove more unnecessary material from the caliper body while maintaining excellent structural strength. The result is a lighter, more compact, and cleaner-looking brake caliper.

Stronger Caliper Body with Fewer Bolts

A traditional split caliper relies on multiple bolts to hold the two caliper halves together. The R2’s one-piece body reduces the need for extra fastening hardware, helping to save weight and improve overall stiffness.

This also gives the caliper a more premium CNC-machined appearance, making it a suitable choice for high-end custom road and gravel builds.

Reinforced Brake Pad Retaining Pin Area

The R2 features a reinforced brake pad retaining pin interface to improve durability around the pad retention area.

On some ultra-light calipers, the brake pad retaining pin can experience additional stress when the brake lever is held while the bike is pushed backward. Over time, this reverse loading can increase the risk of damage around the retaining pin area.

Lewis has strengthened this section of the R2 caliper to better support the brake pad retaining pin and reduce the risk of pin-related failure under reverse braking loads, workshop handling, and demanding riding conditions.

2 × 21mm Titanium Pistons

The R2 is equipped with two large 21mm titanium pistons for strong and consistent braking performance. The larger piston diameter helps deliver reliable braking force, while the titanium piston material helps reduce weight and improve the overall premium specification of the caliper.

7075-T6 Aluminum Body

The caliper body is machined from high-strength 7075-T6 aluminum, a material commonly used in high-performance cycling components where strength, stiffness, and weight reduction are important.

DOT 5.1 and Mineral Oil Versions Available

The Lewis R2 is available in both DOT 5.1 and mineral oil versions, making it compatible with different hydraulic brake systems.

Please select the correct version based on your existing brake lever and hydraulic system. DOT fluid and mineral oil systems are not interchangeable.

Who Is It For?

The Lewis R2 is suitable for:

• Riders building a lightweight road bike

• Climbers looking to reduce total bike weight

• Gravel riders who want a compact and strong flat mount caliper

• Custom bike builders seeking a premium CNC-machined brake upgrade

• Riders who want a cleaner, smaller, and lighter caliper body

• Users who understand their brake system’s fluid type and compatibility requirements

Specifications

Compatibility Notes

Please confirm your brake lever, hose, and hydraulic system before ordering.

DOT 5.1 and mineral oil versions are not cross-compatible. Using the wrong fluid type may damage seals and affect braking performance.

This caliper is designed for flat mount frames and forks. Please check your frame, fork, rotor size, and adapter requirements before installation.