Shimano SLX M666 Disc Brake
Part of the brand new 2012 Shimano SLX groupset, the re-designed SLX disc brakes have brought XTR performance down to a much more attainable level that allows more riders of more budgets to experience what all the fuss is about with the new Shimano brakes. Perhaps one of the best examples of trickle-down technology, the M666 units get the new Ice Tech design that was introduced with the excellent M980 XTR brakes, which aims to reduce the effect that heat has on the braking feel and increases the brakes ability to stay fade-free on long descents. If you really want to sample the braking power and feel of the new XTR and Deore XT brakes but aren't so concerned about weight, the SLX brakes will be an excellent value option for you.

Ice Tech
Brought to the market in 2011 with the gorgeous XTR groupset, the Ice-Tech system is a collection of small details that add up to create a better brake that is more capable of dissipating heat. The most notable of these changes would be the finned Ice Tech brake pads that feature an extended back plates for the pads that sits above the calliper with a series of fins that are designed to increase air flow. By providing a heat sink for the pads, heat generated by strong braking travels up the backing plate and is expelled into the air via the fins. With less heat on the pads, the Mineral Oil inside the brake calliper is kept at a more consistent temperature and the result is stronger braking that doesn't fade on long descents. Another key area that has seen change is the use of full Oversized Ceramic Pistons that not only increase surface area and thus braking force, but are also less heat-affected than metallic pistons and continue the theme of fade-free performance.

Aesthetically, the latest M666 brakes share the inline Master Cylinder as the XTR M980 units, with a much shorter lever blade employed to provide a shorter throw to the brake lever before the pads engage. This compact lever assembly reduces weight over the previous radial piston design and provides a neat setup when meshing your brakes and shifter pods together. The short lever blade is as comfortable as they come and works well with either 1-2 finger braking. The new lever clamp is a split design, so unlike old models you can remove the brakes without having to take off your shifters or grips. Another cool feature is the use of a tool-less reach adjuster that allows you to dial in the correct lever reach for your hands, all without need for tiny allen keys or screwdrivers.

On The Trail
Performance wise, the new SLX brakes just scream power, but unlike other brakes on the market, it is the control of this power that is unique to Shimano. Modulation (the control of power) is excellent and allows you to feather the brakes to avoid locking up brakes. It is this ability to maintain that fine-line between control and sending the bike into the bushes that makes the latest SLX brakes so good whether you're riding steep shoots, off-camber corners or adjusting your speed mid-berm. 
The SLX brakes come pre-bled and ready to mount on your bike, so there's no faffing around trying to cut hydro lines and bleed brakes. And just like all Shimano products SLX is about giving you choice, so you can select between Centrelock or 6-Bolt mounting and any rotor size for front and rear. Just be sure to add on the rotors and adapters you require for your bike and riding style.

 

The Shimano SLX M666 Brake Set Features: