Today, bicycles are elegantly simple machines that are common around the world. Many people ride bicycles for recreation, whereas others use them as a means of transportation. The first bicycle was invented in Germany in 1818. Because it was made of wood, it wasn’t very strong nor did it have pedals (脚踏板).   Riders moved it by pushing their feet against the ground.

In 1839, Kirkpatrick Macmillan, a Scottish blacksmith, invented a much better bicycle. Macmillan’s machine had iron-covered wheels to keep them from getting worn down. He also used foot-operated levers, similar to pedals, so his bicycle could be ridden at a quick pace. It didn’t look much like the modern bicycle, though, because its back wheel was substantially larger than its front wheel. Although Macmillan’s bicycles could be ridden easily, they were never produced in large numbers.

In 1861, Frenchman Pierre Michaux and his brother Ernest invented a bicycle with an improved pedal mechanism. They called their bicycle a VELOCIPEDE, but most people called it a “bone shaker” because of the effect of the wood andiron frame. Despite the impolite nickname, the VELOCIPEDE was a hit. After a few years, the Michaux family was making hundreds of the machines annually, mostly for fun-seeking young people.

Ten years later, James Starley, an English inventor, made several innovations that revolutionized bicycle design. He made the front wheel many times larger than the back wheel, put a gear on the pedals to make the bicycle more efficient, and lightened the wheels by using wire spokes. Although this bicycle was much lighter and less tiring to ride, it was still clumsy, extremely top-heavy, and ridden mostly for entertainment.

It wasn’t until 1874 that the first truly modern bicycle appeared on the scene. Invented by another Englishman, H. J. Lawson, the safety bicycle would look familiar to today’s cyclists. The safety bicycle had equal-sized wheels, which made it easier to ride. Lawson also attached a chain to the pedals to drive the back wheel. By 1893, the safety bicycle had been further improved with air-filled rubber tires, a diamond-shaped frame, and easy braking. With the improvements provided by Lawson; bicycles became extremely popular and useful for transportation. Today, they are built, used, and enjoyed all over the world.

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Cars could be able to "talk" to each other to warn about dangers on the roads using 5G technology in future, according to researchers.

Researchers at Glasgow Caledonian University (GCU) believe 5G may enable driverless cars to send each other messages about dangers such as ice or deep holes.

And they believe the high-speed, low -delay (低延迟的) nature of 5G will improve driverless cars to the point where they will be safer than the cars being driven today. They predict the number of road traffic accidents which cause more than 1. 3 million deaths and up to 50 million people injured worldwide every year will drop greatly as a result.

Dr Dimitrios, a member of the research group, said, “To have a better idea of what the future will look like, think of having cars that not only use sensors (感应器) to find what's around them, but also can talk to each other about safety information nearby.”

“I'm sure anyone who has had a bad experience on frozen roads would have benefited from knowing about the dangerous conditions ahead of time so they could have changed their speed or, if possible, even avoided that route (路线) altogether.”

With the help of 5G, an early warning system in vehicles will come into use within the next few years. Cars that are close enough to the danger area will pass warning messages to other cars around them using communication technologies, but also to cars further away using 5G, fast and reliably. Then those cars will send the same information to cars near them and 80 on, forming a joined-up.

5G is an exciting mobile technology, which will give a great boost to smart cities and autonomous (全自动的) vehicles among many other things.