Räder

Räder is the German word for wheels. In general terms, a wheel is a circular component that rotates around a central axle, reducing friction and enabling rolling motion. Wheels support loads and facilitate movement, especially when paired with bearings and tires that reduce resistance and provide traction.

A typical wheel consists of a rim, a hub, and often spokes that connect the hub to the rim. Spoked wheels offer strength while keeping weight low, whereas solid wheels use a single disc. Tires mounted on rims provide grip, absorb shocks, and protect the wheel from surface irregularities. Bearings between the wheel and axle allow smooth rotation and efficient transfer of forces.

Räder are found in many forms and uses. Solid wheels were common on early carts and machinery, while spoked wheels became widespread for bicycles, wagons, and carriages. Disc wheels are used in some high-performance applications, and caster wheels are small, swiveling wheels used on furniture, equipment carts, and industrial trolleys.

Materials and tires have evolved over time. Early wheels were made from wood, later joined with metal rims. In modern applications, wheels may use aluminum alloys or carbon fiber, with rubber or synthetic tires for most road use. Tires can be pneumatic (air-filled) or solid, and often come with tubeless designs to reduce maintenance.

Historically, the wheel originated around 3500–3000 BCE in Mesopotamia, representing a fundamental technological advance. The wheel and axle, bearing improvements, and eventually rubber tires and mass production shaped transportation, industry, and machinery across civilizations.