Something about bike

A Scotsman named Kirkpatrick MacMillan invented the first bicycle with pedals around 1840. Early bicycles had wooden or metal wheels. However, by the mid-1800s tires with tubes appeared. Modern racing bikes are very lightweight and aerodynamic. The wheels have fewer spokes and the tires are very thin and smooth. Mountain bikes allow riders to ride up and down steep hills on dirt trails. These bikes have fat, knobby tires for extra traction. The tandem is a bicycle for two people. It has about the same wind resistance as a one-person bike. But with twice the power, it goes faster.

Fonte: Collins Dictionary!