Formula

RX Disc Brake

The Formula RX Disc Brake shares the general design and performance of the top shelf R1 in an affordable package. Because of this, you can expect the smooth application of stopping power and consistent lever feel traditionally found in Formula's high-end products -- with only a tiny weight penalty.

The RX master cylinder body works just like its more expensive big brother, but a pressure cast body, as opposed to a forged body, keeps the cost down, as does the use of steel hex-bolt hardware instead of the R1's alloy torx bolts. It can be run moto-style with the rear brake on the left as both lever/master cylinder bodies are identical.

It features the same 22mm diameter pistons as the R1 and both can use the same brake pads. However, where the R1 has an alloy backed organic pad, the RX comes with a steel backed organic pad as standard equipment. It uses a polyester braided hose that works to prevent hose expansion when the system is under extreme pressure. Formula uses DOT 4 brake fluid, which is less temperature-sensitive than mineral oil.

The pistons themselves are made of a heat dissipating composite material and are cupped to provide even more surface area for the fluid to push against and to help shed built-up heat. The one-piece caliper design is stiffer because there are no bolted-together parts to flex along the seam line when you need to stop fast and grab a finger-full of lever. Good ventilation on both the bottom and top of the piston dissipates heat and the top vent also helps make pad changes easy, even with the wheel still in the bike.

The Formula RX Disc Brake is available in Black or White. The price reflects all the parts, save for the rotor which is sold separately in three sizes; 160mm, 180mm, and 203mm. Each size comes with the appropriate adapters. The RX brake weighs 341 grams (with 160mm rotor).