Bicycles

Bicycles
By Leo

A bike, or bicycle, is a vehicle that is ridden on land and is powered by pedals. It was developed in 19th century Europe, and its design has undergone many changes over the years. Today there are over one billion bicycles in the world that are used for transportation and recreation.

Types of Bicycles

There are five types of bicycles:

1. Road bikes
2. Mountain bikes
3. Hybrids
4. Juvenile bikes
5. Specialty bike

Road bikes are regular bikes used to ride on pavement. They have narrow tires which are about 26-27 inches (66-68.5 centimeters) in diameter and have curved handlebars. Road bikes can have three or more gears. You can switch between the gears with dials or leavers located somewhere on the bike. Low gears are good for riding uphill or riding toward the wind. High gears are made for speed especially when you’re riding downhill or with the wind.

Mountain bikes have a heavy duty frame, flat handlebars and thick tires. Mountain Bicycle These features allow them to ride over terrain such as gravel, dirt and grass. Mountain bikes have gear systems with up to 27 gear speeds. Some mountain bikes have front and rear suspension spring systems.

Hybrids are a cross between mountain and road bikes. They are used for on and off road biking. Hybrid tires are thinner than mountain bike tires but fatter than road bikes. Their wheel size is 26” inches in diameter. Their gear systems can have up to 27 gear speeds as well.

Juvenile bikes are designed for children. Sometimes they can be smaller versions of road bikes, mountain bikes or hybrids.

Another kind of bike is a recumbent. The rider leans back on low seats and their legs stretch forward to reach the pedals. Some recumbent bikes are Tandem recumbent bicycle made with an outer shell giving them an aerodynamic advantage by making the wind pass over the shell. This allows the bike to reach speeds of 60 mph (100 kph).

Special bikes have more unusual abilities such as the tandem. It can carry two riders: one in the front and one in the back. Each rider has separate handlebars and pedals, but there is only one chain. The riders can pedal together for extra speed.

Riding a bicycle is a great way to get around for people who don’t have access to an automobile or are too young to drive. Riding a bike is also an economical an environmentally friendly way to travel.

Parts of a Bicycle

The modern bicycle is made up of many different parts. The main parts of the modern bicycle are a metal frame, two wheels, two pedals, handlebars, two brakes and a seat.

The frame is made of welded metal tubes. It looks somewhat like a triangle and a trapezoid connected together.

The wheels are made up of the tire, the rim, the spokes, the hub and the axle.

The tire is made of rubber and is the outer most part of the wheel.

The rim is a metal circle that the tire fits around.

The spokes are thin metal bars that connect the rim to the hub.

The hub is the central area of the wheel. It is made of two circular metal Racing bicycle disks connected by a hollow pole. Inside the hub, there are little metal balls called the ball bearings. They help the hub rotate around the axle smoothly.

The axle is a solid metal rod that fits inside of the hub. It is connected to the bicycle frame with nuts and washers. When the wheel rotates, the hub also rotates while the axle stays still.

The hub and the back wheel are connected to a small gear called the sprocket. There is a larger gear called the chain wheel that is connected to the pedal. These two gears are connected together by a chain made of links. When you pedal, the chain wheel rotates pulling the chain. Then the chain pulls the sprocket turning the hub which rotates the wheel.

The handlebars are what you use to steer the bike, and they also can help you balance. Your body can be used for these purposes too. The lower the handlebars are the faster you go, because when you’re leaning down you gain more speed.

Handlebars can come in three different styles:

1. Flat handlebars are most common and are used for shorter distances.
2. Dropped handlebars are used for long distances and going very fast.
3. High handlebars are normally found on bikes with small wheels such as trick bikes and bikes used for bicycle polo.

Click on each image to view the different styles of handlebars:


Flat handlebars	Dropped handlebars	High handlebars

The handlebars are connected to the front wheel by the head tube and the front fork. When you turn the handlebars, the head tube and front fork turn making the wheel turn with it.

The brake is made up of four parts which include the brake leaver, the brake cable, the brake shoe and the yoke.

The brake leaver is on the handlebar, and when you press it, the bike stops. Some bicycles have two handlebar brakes (one for each wheel), while some have one brake leaver and a pedal back brake.

The brake cable connects the brake and the yoke. When you squeeze the brake leaver, the brake cable pulls up.

The brake shoe squeezes against the rim of the wheel stopping its motion. There is a brake shoe on both wheels.

The yoke is the part that connects the brake shoe and the brake cable together. When the brake cable pulls up, it pulls on the yoke which pulls on the brake shoe which then squeezes against the wheel and stops the bicycle.

The seat is the place that you sit on when you’re riding a bike. It can also be called the saddle. You can adjust the seat to a different height. When you’re sitting, your feet should touch the ground.

Citations

Online Resources

"Bicycle." World Book Online Reference Center. 17 December 2004 <http://www.worldbookonline.com/wb/PrintArticle?id=ar058580&st=Bicycle>.

Brain, Marshall. "How Bicycles Work." How Stuff Works. 2 January 2005 <http://travel.howstuffworks.com/bicycle.htm/printable>.

Images

Permission to use all photographs of bicycles is granted under the terms of the GNU Free Documentation License from Wikipedia, the Free Encyclopedia. <http://en.wikipedia.org/wiki/Main_Page>.

Copyrighted animated image of bicycle from "Microsoft Office Online" <http://office.microsoft.com/clipart/default.aspx?lc=en-us&cag=1> (October-March, 2004-2005). Clip art available only to licensed users for non-commercial purposes.