Blessed with trickledown technology, the Formula RX Disc Brake shares the general design and performance of the top shelf R1 -- but in an extremely affordable package. You can expect to get that same smooth application of stopping power and consistent lever feel that you expect from Formula's high-end products, with only a tiny weight penalty.
The Formula RX Brake employs the new radial design master cylinder. 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).
Please note: almost all hydraulic brake lines need to be cut to size before a bike is properly shod with hydraulic disc brakes. You'll need a quality cable-cutter like the Park CN-10 and a spoke to first cut and then de-crimp the housing.
I'm no my second set of these, I have used several different sets of Elixir 3's and 5's as well as some others and have come back to the RX's. They are light, powerful, and have a great price. I'm running mine with 180/160 Ashima Airotors that are light and cheap. I'm at the end of the life of the organic pads and will try out the Formula sintered pads.