Bicycle

A bicycle is a small [land vehicle]? with two wheels (hence the name) powered by a human rider. A bicycle is a form of transportation

Riding bicycles is a common recreation and popular sport.

Variations on the vehicle include:

• more wheels: tricycle?s and so on
• one wheel: unicycle?
• more passengers: [tandem bicycle]?

What we really need is a picture:

And an article on [bicycle repair and maintenance]?.

The picture should label the following parts: frame, top tube, down tube, seat tube, seat post, headset (head set?), handlebars, front forks, rear forks, chain stay, rear stay, wheel, wheel rim, wheel axle, spoke, spoke flange, brakes, brake levers, saddle, bottom bracket, crankshaft, cranks, pedal, chain, chainring, rear gears. Also the parts which vary a bit more: toe clips, cleats, gear changers, hub gears, derailleur gears, front gear block, rear gear block (aka cassette), mud guards, chain guards (both on the stay and around the chain), lights, panniers.

An article on [bicycle brake systems]? might be useful.

And maybe at least one reference to a sports science article that explains how cycling is the most efficient form of human powered transport.

It has often been observed that a fish is not likely to need a bicycle.

Powered bicycles are also known as motorcycles, mopeds?, and scooters?.

Another form of two wheeled vehicle is the push cycle.