Disc brake in the context of Renault

Gray iron, or grey cast iron, is a type of cast iron that has a graphitic microstructure. It is named after the gray color of the fracture it forms, which is due to the presence of graphite. It is the most common cast iron and the most widely used cast material based on weight.

It is used for housings where the stiffness of the component is more important than its tensile strength, such as internal combustion engine cylinder blocks, pump housings, valve bodies, electrical boxes, and decorative castings. Grey cast iron's high thermal conductivity and specific heat capacity are often exploited to make cast iron cookware and disc brake rotors.

A brake is a mechanical device that inhibits motion by absorbing energy from a moving system. It is used for slowing or stopping a moving vehicle, wheel, axle, or to prevent its motion, most often accomplished by means of friction.

Mountain biking (abbr. MTB) is a sport of riding bicycles off-road, often over rough terrain, usually using specially designed mountain bikes. Mountain bikes share similarities with other bikes but incorporate features designed to enhance durability and performance in rough terrain, such as air or coil-sprung shocks used as suspension, larger and wider wheels and tires, stronger frame materials, and mechanically or hydraulically actuated disc brakes. Mountain biking can generally be broken down into distinct categories: cross country, trail, all mountain, enduro, downhill and freeride.

A superhard material is a material with a hardness value exceeding 40 gigapascals (GPa) when measured by the Vickers hardness test. They are virtually incompressible solids with high electron density and high bond covalency. As a result of their unique properties, these materials are of great interest in many industrial areas including, but not limited to, abrasives, polishing and cutting tools, disc brakes, and wear-resistant and protective coatings.

Diamond is the hardest known material to date, with a Vickers hardness in the range of 70–150 GPa. Diamond demonstrates both high thermal conductivity and electrically insulating properties, and much attention has been put into finding practical applications of this material. However, diamond has several limitations for mass industrial application, including its high cost and oxidation at temperatures above 800 °C. In addition, diamond dissolves in iron and forms iron carbides at high temperatures and therefore is inefficient in cutting ferrous materials including steel. Therefore, recent research of superhard materials has been focusing on compounds which would be thermally and chemically more stable than pure diamond.

Mountain unicycling is an adventure sport that consists of traversing rough terrain on a unicycle. Mountain unicycling (muni or municycling) is undertaken on similar terrain to mountain biking. However, muni requires much more attention to the microfeatures of the short distance in front of the wheel. Unicycles' lack of a freewheel means that descents must be controlled all the way, and the typical lack of a gear system (though two-gear hubs are available) prevents the rider from reaching high speeds. Muni usually takes place on specially designed unicycles, which are equipped with strong hubs, large, knobbly tires, high-grip pedals and rugged frames. Some are also equipped with rim or disc brakes, having the lever mounted under the nose of the saddle. The brake primarily helps to compensate the downhill-slope force, while more expert riders also use it to decelerate or stop.

Muni riders also need a few additional skills than required for either mountain biking or regular unicycling, with core strength, endurance and balance being key.