polkupyörillä

Polkupyörillä, commonly known as bicycles, are human-powered vehicles with two wheels attached to a frame. They are propelled by the rider pushing pedals attached to a crankset, which in turn drives the rear wheel via a chain and gears. This mechanical advantage allows for efficient locomotion and transport.

The history of the bicycle dates back to the early 19th century, with numerous inventors contributing to its development. Early models like the velocipede and the high-wheeler were less stable and comfortable than modern designs. The invention of the safety bicycle in the late 1880s, featuring two wheels of equal size and a chain drive, revolutionized cycling and laid the groundwork for the bicycles we use today.

Bicycles are used for a wide variety of purposes, including transportation, recreation, exercise, and sport. They are an environmentally friendly mode of transport, producing no emissions. Cycling offers significant health benefits, improving cardiovascular fitness and muscle strength. Various types of bicycles exist to suit different needs, such as road bikes for speed on paved surfaces, mountain bikes for off-road terrain, and hybrid bikes for a combination of uses. The design typically includes handlebars for steering, a saddle for seating, and brakes for stopping.