Essential Bicycle Components and Braking Systems

Bicycle Cranksets and Bottom Brackets

Cranks (Manovellas) are the connecting rods that link the bottom bracket to the pedals. The length of the crank depends on the type of route you intend to ride. A short crank allows for a higher cadence and is suitable for irregular terrain, while longer cranks provide better performance on long, steady stretches. Most mountain bike cranks are made of metal or lightweight steel alloys, though other materials are also available.

The Bottom Bracket

The bottom bracket comprises a central axis that is typically protected and ends with a square taper where the crank is inserted. It is essential to keep the bottom bracket tightly closed to prevent rust (robella). Whenever maintenance or a repair is performed, the component should be thoroughly cleaned and greased.

The Derailleur and Shifting Mechanics

The derailleur is designed to change the chain from one chainring to another. Its range of motion can be regulated using two small adjustment screws (pins). For optimal performance, the distance between the derailleur and the large chainring should be maintained between 2mm and 5mm.

Braking System Fundamentals

The most widely used braking systems act directly on the wheel rim. Aluminum wheels are typically used because the material dissipates heat effectively, as they are exposed to the air and cool rapidly during use.

Cantilever Brakes

Cantilever brakes are made of lightweight materials and alloys that provide excellent results. They consist of two levers joined by a small transverse cable, while another wire forms an inverted 'V'. Each arm contains a device that allows for alignment with the rims. This system does not require extensive maintenance.

V-Brakes (Broke)

V-Brakes also feature two lever arms, but they are longer and arranged in an inverted 'U' shape. A single cable passes through the two levers, making the system more solid, compact, and providing more secure braking power.

Gear Levers and Shifting Devices

Gear levers are responsible for managing cable tension to achieve different gear positions. The main objective is to ensure the rider can utilize the maximum percentage of force applied to the pedals. These levers are usually located at the bottom of the handlebars for convenient handling. Alternatively, the Grip Shift is a cylinder built into the handlebars that the rider rotates to change gears while driving.

Disc Brakes

Disc brakes offer higher braking power that does not depend on the physical state of the bicycle wheel. While they are heavier than conventional rim systems, they were first popularized on Downhill (DH) bikes. A major drawback is their vulnerability to hard impacts (copetja). These systems can be mechanical (actuated by cable) or hydraulic (actuated by oil).

Rear Derailleur Characteristics

The rear derailleur is the device that allows the chain to move between different sprockets (pinions). This is a critical component to evaluate when buying a bicycle. Key characteristics include being resistant, rapid, and possessing millimeter-precision. It should be easy to use and consists of three main components: the diverter, the back-hand, and the hand-lever.