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Sunday, 12 August 2012

>English Grammar

English Grammar

English grammar is the body of rules that describe the structure of expressions in the English language. This includes the structure of words, phrases, clauses, and sentences.
There are historical, social, and regional variations of English. Divergences from the grammar described here occur in some dialects of English. This article describes a generalized present-day Standard English, the form of speech found in types of public discourse including broadcasting, education, entertainment, government, and news reporting, including both formal and informal speech. There are certain differences in grammar between the standard forms of British English, American English, and Australian English, although these are inconspicuous compared with the lexical and pronunciation differences.

Word classes and phrases

Eight word classes (parts of speech) are distinguished in English: noun, determiner, pronoun, verb, adjective, adverb, preposition, and conjunction. (Determiners, traditionally classified along with adjectives, have not always been regarded as a separate part of speech.) Another word class is interjection, but this is not described here as it does not form part of the clause and sentence structure of the language.[1]
Nouns, verbs, adjectives, and adverbs form open classes – word classes that readily accept new members, such as the noun celebutante (a celebrity who frequents the fashion circles), the adverb 24/7 (as in I am working on it 24/7), and similar relatively new words.[1] The others are regarded as closed classes; it is rare for a new pronoun, for example, to be admitted to the language.
English words are not generally marked for word class. It is not usually possible to tell from the form of a word which class it belongs to (except, to some extent, in the case of words with inflectional endings or derivational suffixes). Some words belong to more than one word class; for example run can serve as either a verb or a noun (these are regarded as two different lexemes).[2] Lexemes may be inflected to express different grammatical categories; the lexeme run has the forms runs, ran, and running.[2] Words in one class can sometimes be derived from those in another; this can give rise to new words, for example the noun aerobics has recently given rise to the adjective aerobicized.[2]
Words combine to form phrases. A phrase typically serves the same function as a word from some particular word class.[2] For example, my very good friend Peter is a phrase that can be used in a sentence as if it were a noun, and is therefore called a noun phrase. Similarly, adjective phrases and adverb phrases function as if they were adjectives or adverbs; but with other types of phrase the terminology has different implications. For example, a verb phrase consists of a verb together with any objects and other dependents; a prepositional phrase consists of a preposition together with its complement (and is therefore usually a type of adverb phrase); and a determiner phrase is a type of noun phrase containing a determiner.

Nouns

Nouns form the largest English word class. There are many common suffixes used to form nouns from other nouns or from other types of words, such as -age (as in shrinkage), -hood (as in sisterhood), and so on,[2] although many nouns are base forms not containing any such suffix (such as cat, grass, France). Nouns are also often created by conversion of verbs or adjectives, as with the words talk and gay (a boring talk, a group of gays).
Unlike in many related languages, English nouns do not have grammatical gender (although many nouns refer specifically to male or female persons or animals, like mother, father, bull, tigress; see Gender in English). Nouns are sometimes classified semantically (by their meanings): as proper nouns and common nouns (Cyrus, China vs. frog, milk), or as concrete nouns and abstract nouns (book, laptop vs. heat, prejudice).[3] A grammatical distinction is often made between count (countable) nouns such as clock and city, and non-count (uncountable) nouns such as milk and decor.[4] A given noun can function in more than one class; for example, wine can be either countable or uncountable (this is a good wine, I prefer red wine).
Countable nouns generally have singular and plural forms.[3] In most cases the plural is formed from the singular by adding -[e]s (as in dogs, bushes), although there are also irregular forms (woman/women, medium/media, etc.), including cases where the two forms are identical (sheep, series). For details, see English plural.
Certain nouns can take plural verbs even though they are singular in form, as in The government were ... (where the government is considered to refer to the people constituting the government). This is more common in British than American English. See Synesis.
English nouns are not marked for case as they are in some languages, but they have possessive forms, formed by the addition of -'s (as in John's, children's), or just an apostrophe (with no change in pronunciation) in the case of -[e]s plurals and sometimes other words ending with -s (the dogs' owners, Jesus' love). This is sometimes called the Saxon genitive. More generally, the ending can be applied to noun phrases (as in the man you saw yesterday's sister); see below. The possessive form can be used either as a determiner (John's cat) or as a noun phrase (John's is the one next to Jane's).

Noun phrases

Noun phrases are phrases that function grammatically as nouns within sentences, for example as the subject or object of a verb. Most noun phrases have a noun as their head.[4]
A noun phrase typically takes the following form (not all elements need be present):
Determiner + Other pre-modifiers + NOUN + Post-modifiers/Complement
In this structure:
  • the determiner may be an article (the, a[n]) or other equivalent word, as described in the following section. In many contexts some determiner is required to complete the noun phrase.
  • other pre-modifiers include adjectives and some adjective phrases (such as red, really lovely), and noun adjuncts (such as college in college student). Adjectival modifiers usually come before modifiers that are nouns.
  • the complement or post-modifier,[4] if present, may be a prepositional phrase (... of London), a relative clause (like  ...which we saw yesterday), certain adjective or participial phrases (... sitting on the beach), or certain clauses appropriate to the noun (like ... that the world is round after a noun such as fact or statement).
An example of a noun phrase that includes all of the above-mentioned elements is that rather attractive young college student that you were talking to. Here that is the determiner, rather attractive and young are adjectival pre-modifiers, college is a noun used as a pre-modifier, student is the noun serving as the head of the phrase, and that you were talking to is a post-modifier (a relative clause in this case). Notice the order of the pre-modifiers; the determiner that must come first, and the noun modifier college must come after the adjectival modifiers.
Conjunctions such as and, or, and but can be used at various levels in noun phrases, as in John, Paul, and Mary; the matching green coat and hat; a dangerous but exciting ride; a person sitting down or standing up.
Noun phrases can also be placed in apposition (where two consecutive phrases refer to the same thing), as in that president, Abraham Lincoln, ... (where that president and Abraham Lincoln are in apposition). In some contexts the same can be expressed by a prepositional phrase, as in the twin curses of famine and pestilence (meaning "the twin curses" that are "famine and pestilence").
Particular forms of noun phrases include:
  • phrases formed by the determiner the with an adjective, as in the homeless, the English (these are plural phrases referring to homeless people or English people in general);
  • phrases with a pronoun rather than a noun as the head (see below);
  • phrases consisting just of a possessive (see the paragraph above on Saxon genitives);
  • infinitive and gerund phrases, in certain positions;
  • certain clauses, such as that clauses and relative clauses like what he said, in certain positions.

Determiners

English determiners constitute a relatively small class of words; they include the articles the, a[n] (and in some contexts some), certain demonstrative and interrogative adjectives words such as this, that, and which, possessives such as my and whose (the role can also be played by Saxon genitive forms such as John's and the girl's), and various quantifying words like all, many, various, as well as numerals (one, two, etc.). There also exist many phrases (such as a couple of) that can play the role of determiners.
Determiners are used in the formation of noun phrases (see above). Many words that serve as determiners can also be used as pronouns (this, that, many, etc.)
Determiners can be used in certain combinations, such as all the water, the many problems, etc.
In many contexts it is required for a noun phrase to be completed with an article or some other determiner. It is not grammatical to say just cat sat on table; one must say (for example) my cat sat on the table. The most common situations in which a complete noun phrase can be formed without a determiner are when it refers generally to a whole class or concept (as in dogs are dangerous and beauty is subjective), and when it is a name (Jane, Spain, etc.) This is discussed in more detail at English articles.

Pronouns

Pronouns are a small class of words that function as noun phrases. They include personal pronouns, demonstrative pronouns, relative pronouns, interrogative pronouns, and others.

Personal pronouns

The personal pronouns of modern standard English, and the corresponding possessive forms, are as follows:

Nominative Oblique Reflexive Possessive determiner Possessive pronoun
1st pers. sing. I me myself my mine
2nd pers. sing./pl. you you yourself/yourselves your yours
3rd pers. sing. she, he, it her, him, it herself, himself, itself her, his, its hers, his, (rare: its)
1st pers. pl. we us ourselves our ours
3rd pers. pl. they them themselves their theirs
The second-person forms you etc. are used with both singular and plural reference. (An archaic set of pronouns used for singular reference is thou, thee, thyself, thy, thine.) You can also be used as an indefinite pronoun, referring to a person in general; a more formal alternative is one (reflexive oneself, possessive one's).
The third-person singular forms are differentiated according to the sex of the referent: she etc. are used to refer to a female person, sometimes a female animal, and sometimes an object to which female characteristics are attributed, such as a ship or a country. A male person, and sometimes a male animal, is referred to using he etc. In other cases it etc. are used. The word it can also be used as a dummy subject, in sentences like it is wrong to avoid tax.
The third-person plural forms they etc. are sometimes used with singular reference, as a gender-neutral pronoun, as in each employee should ensure they tidy their desk. This usage is sometimes considered ungrammatical.
The possessive deteminers (my etc.) are used as determiners to form noun phrases, as in my old man, some of his friends. The second possessive forms (mine etc.) are used when they do not qualify a noun: as pronouns, as in mine is bigger than yours, and as predicates, as in this one is mine. Note also the construction a friend of mine (meaning "someone who is my friend").

Demonstrative and interrogative pronouns

The demonstrative pronouns of English are this (plural these), and that (plural those), as in these are good, I like that. Note that all four words can also be used as determiners (followed by a noun), as in those cars.
The interrogative pronouns are who, what, and which (all of them can take the suffix -ever for emphasis). The pronoun who refers to a person or people; it has an oblique form whom (though in informal contexts this is usually replaced by who), and a possessive form (pronoun or determiner) whose. The pronoun what refers to things or abstracts. The word which is used to ask about alternatives from what is seen as a closed set: which (of the books) do you like best? (It can also be an interrogative determiner: which book?; this can form the alternative pronominal expressions which one and which ones.) Which, who, and what can be either singular or plural. (Examples: Which is the highest hill? Which are the highest hills? Who was born in 1920? Who were king and queen in 1920?). But who and what often take a singular verb regardless of any supposed number; the questions Who wants some cake? and What's in the bag? do not presuppose anything about number in possible responses: I want some cake, or All of us want some; and A rabbit is in the bag, or Five coins and a bus ticket.[5]
All the interrogative pronouns can also be used as relative pronouns; see below.

Relative pronouns

The main relative pronouns in English are that, which, who, whom, and whose.
The first of these, that, can refer to either persons or things, is normally restricted to restrictive relative clauses, and cannot follow a preposition. For example, the song that I listened to yesterday, but the song to which (not *to that) I listened yesterday. The relative pronoun that is usually pronounced with a reduced vowel (schwa), and hence differently from the demonstrative that (see Weak and strong forms in English). If that is not the subject of the relative clause, it can be omitted (the song I listened to yesterday).
The relative pronoun which refers to things rather than persons, as in the shirt, which used to be red, is faded. For persons, who is used (the man who saw me was tall). The oblique case form of who is whom, as in the man whom I saw was tall, although in less formal registers who is commonly used in place of whom.
The possessive form of who is whose (the man whose car is missing ...); however the use of whose is not restricted to persons (one can say an idea whose time has come).
The word what can be used to form a relative clause that has no antecedent and that serves as a complete noun phrase in itself, as in I like what he likes. The words whatever and whichever can be used similarly, in the role of either pronouns (whatever he likes) or determiners (whatever book he likes).
For more detail on the use of these pronouns, see English relative clauses.

There as pronoun

The word there is used as a pronoun in some sentences, most commonly with forms of the verb be in existential clauses, to indicate the presence or existence of something (analogous to existential quantification in predicate logic). The pronoun serves as a "dummy subject" taking the place of the logical subject, which usually appears after the verb. For example: There is a heaven; There are two cups on the table; There have been a lot of problems lately; There occurred a very strange incident.
The dummy subject can undergo inversion, as in Is there a God? and Never has there been a man such as this. It can also appear without a corresponding logical subject, in short sentences and question tags: There wasn't a discussion, was there? There was.
The word there can also function as a deictic adverb (meaning "at/to that place") particle. Consequently a sentence like There is a river could have either of two meanings: "a river exists" (with there as a pronoun), and "a river is in that place" (with there as an adverb). In speech, the adverbial there would be given stress, while the pronoun would not – in fact the pronoun is often pronounced as a weak form, /ðə(r)/.

Other pronouns

Other pronouns in English are often identical in form to determiners (especially quantifiers), such as many, a little, etc. Sometimes the pronoun form is different, as with none (corresponding to the determiner no), nothing, everyone, somebody, etc. Many examples are listed at Indefinite pronoun.

Verbs

Verbs form the second largest word class after nouns. The basic form of an English verb is not generally marked by any ending, although there are certain suffixes that are frequently used to form verbs, such as -ate (formulate), -fy (electrify), and -ise/ize (realise/realize).[6] Many verbs also contain prefixes, such un- (unmask), out- (outlast), over- (overtake), and under- (undervalue).[6] Verbs can also be formed from nouns and adjectives by conversion, as with the verbs snare, nose, dry, and calm.
Most verbs have three or four inflected forms: a third-person singular present tense form in -s (writes), a present participle and gerund form in -ing (writing), a past tense (wrote), and – though often identical to the past tense form – a past participle (written). Regular verbs have identical past tense and past participle forms in -ed, but there are 100 or so irregular English verbs with different forms (see list). The verbs have and do also have irregular third-person present tense forms (has, does [dʌz]). The verb be has the largest number of irregular forms (am, is, are in the present tense, was, were in the past tense, been for the past participle).
Most of what are generally referred to as verb tenses (or sometimes aspects) in English are formed using auxiliaries. Apart from what are called the simple present (write, writes) and simple past (wrote), there are also continuous (progressive) forms (am/is/are/was/were writing), perfect forms (have/has/had written, and the perfect continuous have/has/had been writing), future forms (will write, will be writing, will have written, will have been writing), and conditionals (also called "future in the past") with would in place of will. The auxiliaries shall and should sometimes replace will and would in the first person. For the uses of these tenses and other verb forms, see English verbs.
The infinitive is the basic form of the verb (be, write, play), although there is also a "to-infinitive" (to be, to write, to play) used in many syntactical constructions. There are also infinitives corresponding to other aspects: (to) have written, (to) be writing, (to) have been writing. The second-person imperative is identical to the (basic) infinitive; other imperative forms may be made with let (let us go, or let's go; let them eat cake).
A form identical to the infinitive can be used as a present subjunctive in certain contexts: It is important that he follow them or ... that he be committed to the cause. There is also a past subjunctive (distinct from the simple past only in the possible use of were instead of was), used in some conditional sentences and similar: if I were (or was) rich ...; were he to arrive now ...; I wish she were (or was) here. For a full description, see English subjunctive.
The auxiliary do (does, did), used with the basic infinitive, makes an emphatic form of a verb (I do like you; he does speak English; we did close the fridge). It is this form that is used to make interrogatives and negatives of most verbs (do I like you?; he doesn't speak English). For verbs that do not take the auxiliary do ("special verbs"), see below.
The passive voice is formed using the verb be (in the appropriate tense, aspect or form) with the past participle of the verb in question: cars are driven, he was killed, I am being tickled, it is nice to be pampered, etc. The "logical subject" may be introduced in a prepositional phrase with by (as in they were killed by the invaders).
English has a set of modal verbs: the core modals can, could, shall, should, will, would, may, might, must, as well as ought (to), had better, and in some uses dare and need.[7] These do not inflect for person or number,[7] and do not have infinitive or participle forms (except synonyms, as with be/being/been able (to) for the modals can/could). The modals are used with the basic infinitive form of a verb (I can swim, he may be killed, we dare not move, need they go?), except for ought, which takes to (you ought to go).
The verb be along with the auxiliary and modal verbs form a class sometimes called "special verbs". These have different syntax from ordinary lexical verbs, especially in that they make their interrogative forms by plain inversion and their negative forms simply by adding not (could I ...? I could not ...). Apart from those already mentioned, this class may also include used to (although the forms did he use to? and he didn't use to are also found), and sometimes have even when not an auxiliary (forms like have you a sister? and he hadn't a clue are possible, though less common in modern English than the alternatives do you have ...?, he didn't have, etc.).
Some of these special verbs can combine with their subject in a contracted form, such as I'm for I am, you'd for you would or you had, John's for John is. For negative forms, see Negation below.

Verb phrases

In some theories of grammar, a verb phrase consists of a verb together with its dependents, which may be objects, complements, and modifiers (adverbs or adverbial phrases). Objects and complements nearly always come after the verb; a direct object precedes other complements such as prepositional phrases, but if there is an indirect object as well, expressed without a preposition, then that precedes the direct object: give me the book, but give the book to me. Adverbial modifiers generally follow objects, although other positions are possible (see under Adverbs below).
Dependency grammars reject the concept of finite verb phrases as clause constituents. See the verb phrase article for more information.
Particular types of non-finite verb phrases in English are infinitive phrases, such as (to) buy a present for Dad (see also the article on split infinitive), and participial phrases, such as playing cricket on the green.

Adjectives

English adjectives, as with other word classes, cannot in general be identified as such by their form,[8] although many of them are formed from nouns or other words by the addition of a suffix, such as -al (habitual), -ful (blissful), -ic (atomic), -ish (impish, youngish), -ous (hazardous), etc.; or from other adjectives using a prefix: disloyal, irredeemable, unforeseen, overtired.
Adjectives may be used attributively, as part of a noun phrase (nearly always preceding the noun they modify), as in the big house, or predicatively, as in the house is big. Certain adjectives are restricted to one or other use; for example, drunken is attributive (a drunken sailor), while drunk is usually predicative (the sailor was drunk).
Many adjectives have comparative and superlative forms in -er and -est,[9] such as hot, hotter, hottest. Common irregular forms include good, better, best and bad, worse, worst. Many others, however (particularly longer and less common adjectives) do not have such forms; instead they can be qualified with more and most, as in beautiful, more beautiful, most beautiful.
Certain adjectives are classed as ungradable.[9] These represent properties that cannot be compared on a scale; they simply apply or do not, as with pregnant, dead, unique. Consequently, comparative and superlative forms of such adjectives are not normally used, except in a figurative, humorous or imprecise context. Similarly, such adjectives are not normally qualified with modifiers of degree such as very and fairly, although with some of them it is idiomatic to use adverbs such as completely. Another type of adjectives sometimes considered ungradable is those that represent an extreme degree of some property, such as delicious and terrified; the same point about modifiers applies to these, although it is not rare to find them in comparative or superlative form.

Adjective phrases

An adjective phrase is a group of words that plays the role of an adjective in a sentence. It usually has a single adjective as its head, to which modifiers and complements may be added.[10]
Adjectives can be modified by a preceding adverb or adverb phrase, as in very hot, truly imposing, more than a little excited. Some can also be preceded by a noun or quantitative phrase, as in fat-free, two-metre-long.
Complements following the adjective may include:
  • prepositional phrases: proud of him, angry at the screen, keen on breeding toads;
  • infinitive phrases: anxious to solve the problem, easy to pick up;
  • that clauses and certain other clauses: certain that he was right, unsure where they are;
  • after comparatives, phrases or clauses with than: better than you, smaller than I had imagined.
An adjective phrase may include both modifiers before the adjective and a complement after it, as in very difficult to put away.
Adjective phrases containing complements after the adjective cannot normally be used as attributive adjectives before a noun. Sometimes they are used attributively after the noun, as in a woman proud of being a midwife (where they may be converted into relative clauses: a woman who is proud of being a midwife), but it is wrong to say *a proud of being a midwife woman. Exceptions include very brief and often established phrases such as easy-to-use. (Certain complements can be moved to after the noun, leaving the adjective before the noun, as in a better man than you, a hard nut to crack.)
Certain attributive adjective phrases are formed from other parts of speech, without any adjective as their head, as in a two-bedroom house, a no-jeans policy.

Adverbs

Adverbs perform a wide range of functions, typically modifying verbs (or verb phrases), adjectives (or adjective phrases), or other adverbs (or adverb phrases),[11] although they also sometimes qualify noun phrases (only the boss, quite the loveliest place), pronouns and determiners (almost all) and prepositional phrases (halfway through the movie), indicate an attitude or comment on a whole sentence (frankly, I don't believe you),[12] or indicate the relation between clauses or sentences (he died, and consequently I inherited the estate).[12]
Many English adverbs are formed from adjectives, by adding the ending -ly,[13] as in hopefully, widely, theoretically (but the adjective good corresponds to the adverb well). Certain words can be used as both adjectives and adverbs, such as fast, straight, and hard.
There are also a large number of adverbs that are not derived from adjectives,[11] including adverbs of time (today, soon, then), of place (here, there, everywhere), of degree (very, much, quite, so, too), and with other meanings (only, just, however, therefore). Some suffixes that are fairly commonly used to form adverbs from nouns are -ward[s] (as in homeward[s]) and -wise (as in lengthwise).
A few adverbs inflect for comparative and superlative forms:[11] much, more, most; a little, less, least; soon, sooner, soonest; well, better, best; badly, worse, worst; far, further (farther), furthest (farthest); fast, faster, fastest, etc. However most form comparatives and superlatives by modification with more and most: often, more often, most often; smoothly, more smoothly, most smoothly (see also comparison of adjectives, above).
Adverbs indicating the manner of an action are most usually placed after the verb and its objects (We considered the proposal carefully), although other positions are often possible. Many adverbs of frequency, degree, certainty, etc. (such as often, always, almost, probably, and various others such as just) tend to be placed before the verb (they usually have chips), although if there is an auxiliary or other "special verb" (see Verbs above), then the normal position for such adverbs is after the special verb (or after the first of them, if there is more than one): I have just finished the crossword, she can usually manage a pint, we are never late, you might possibly have been unconscious. Adverbs that provide a connection with previous information (such as next, then, however), and those that provide a context (such as time or place) for the sentence, often come at the start of the sentence: Yesterday we went on a shopping expedition.[14]
A special type of adverb is the adverbial particle used to form phrasal verbs (such as up in pick up, on in get on, etc.) If such a verb also has an object, then the particle may precede or follow the object, although it will normally follow the object if the object is a pronoun (pick the pen up or pick up the pen, but pick it up).

Adverb phrases

An adverb phrase is a phrase that acts as an adverb within a sentence.[15] An adverb phrase may have an adverb as its head, together with any modifiers (other adverbs or adverb phrases) and complements, analogously to the adjective phrases described above. For example: very sleepily, all too suddenly, oddly enough, perhaps shockingly for us.
Another very common type of adverb phrase is the prepositional phrase, which consists of a preposition and its object: in the pool, after two years, for the sake of harmony.

Prepositions

Prepositions form a closed word class,[12] although there are also certain phrases that serve as prepositions, such as in front of. A single preposition may have a variety of meanings, often including temporal, spatial and abstract. Many words that are prepositions can also serve as adverbs. Examples of common English prepositions (including phrasal instances) are of, in, on, over, under, to, from, with, in front of, behind, opposite, by, before, after, during, through, in spite of or despite, between, among, etc.
A preposition is usually used with a noun phrase as its complement. A preposition together with its complement is called a prepositional phrase.[16] Examples are in England, under the table, after six pleasant weeks, between the land and the sea. A prepositional phrase can be used as a complement or post-modifier of a noun in a noun phrase, as in the man in the car, the start of the fight; as a complement of a verb or adjective, as in deal with the problem, proud of oneself; or generally as an adverb phrase (see above).
English allows the use of "stranded" prepositions. This can occur in interrogative and relative clauses, where the interrogative or relative pronoun that is the preposition's complement is moved to the start, leaving the preposition in place. This kind of structure is avoided in some kinds of formal English. For example:
  • What are you talking about? (Possible alternative version: About what are you talking?)
  • The song that you were listening to ... (more formal: The song to which you were listening ...)
Notice that in the second example the relative pronoun that could be omitted.
Stranded prepositions can also arise in passive voice constructions and other uses of past participial phrases, where the complement in a prepositional phrase can become zero in the same way that a verb's direct object would: it was looked at; I will be operated on; get your teeth seen to. The same can happen in certain uses of infinitive phrases: he is nice to talk to; this is the page to make copies of.

Conjunctions

Conjunctions express a variety of logical relations between items, phrases, clauses and sentences.[17] The principal coordinating conjunctions in English are and, or, and but, as well as nor. These can be used in many grammatical contexts to link two or more items of equal grammatical status,[17] for example:
  • Noun phrases combined into a longer noun phrase, such as John, Eric, and Jill, the red coat or the blue one. When and is used, the resulting noun phrase is plural. A determiner does not need to be repeated with the individual elements: the cat, the dog, and the mouse or the cat, dog, and mouse are both correct. The same applies to other modifiers. (The word but can be used here in the sense of "except": nobody but you.)
  • Adjective or adverb phrases combined into a longer adjective or adverb phrase: tired but happy, over the fields and far away.
  • Verbs or verb phrases combined as in he washed, peeled, and diced the turnips (verbs conjoined, object shared); he washed the turnips, peeled them, and diced them (full verb phrases, including objects, conjoined).
  • Other equivalent items linked, such as prefixes linked in pre- and post-test counselling.,[18] numerals as in two or three buildings, etc.
  • Clauses or sentences linked, as in We came but they wouldn't let us in. They wouldn't let us in, nor would they explain what we had done wrong.
There are also correlative conjunctions, where as well as the basic conjunction, an additional element appears before the first of the items being linked.[17] The common correlatives in English are:
  • either ... or (either a man or a woman);
  • neither ... nor (neither clever nor funny);
  • both ... and (they both punished and rewarded them);
  • not ... but, particularly in not only ... but also (not exhausted but exhilarated, not only football but also many other sports).
Subordinating conjunctions make relations between clauses, making the clause in which they appear into a subordinate clause.[19] Some common subordinating conjunctions in English are:
  • conjunctions of time, including after, before, since, until, when, while;
  • conjunctions of cause and effect, including because, since, now that, as, in order that, so;
  • conjunctions of opposition or concession, such as although, though, even though, whereas, while;
  • conjunctions of condition: such as if, unless, only if, whether or not, even if, in case (that);
  • the conjunction that, which produces content clauses, as well as words that produce interrogative content clauses: whether, where, when, how, etc.
A subordinating conjunction generally comes at the very start of its clause, although many of them can be preceded by qualifying adverbs, as in probably because ..., especially if .... The conjunction that can be omitted after certain verbs, as in she told us (that) she was ready.

Negation

As noted above under Verbs, a finite verb (or its clause) is negated by placing the word not after an auxiliary, modal or other "special" verb such as do, can or be. For example, the clause I go is negated with the addition of the auxiliary do, as I do not go. When the affirmative already uses auxiliary verbs (I am going), no other auxiliary verbs are added to negate the clause (I am not going). (Until the period of early Modern English, negation without the use of any auxiliary verbs was used: I go not.)
Most combinations of auxiliary verbs etc. with not have contracted forms: don't, can't, isn't, etc. (Also the uncontracted negated form of can is written as a single word cannot.) On inversion of subject and verb (such as in questions; see below), the subject may be placed after a contracted negated form: Should he not pay? or Shouldn't he pay?
Other elements, such as noun phrases, adjectives, adverbs, infinitive and participial phrases, etc., can be negated by placing the word not before them: not the right answer, not interesting, not to enter, not noticing the train, etc.
When other negating words such as never, nobody, etc. appear in a sentence, the negating not is omitted (unlike its equivalents in many languages): I saw nothing or I didn't see anything, but not (except in non-standard speech) *I didn't see nothing.

Clause and sentence structure

A typical sentence contains one independent clause and possibly one or more dependent clauses, although it is also possible to link together sentences of this form into longer sentences, using coordinating conjunctions (see above).
A clause typically contains a subject (a noun phrase) and a predicate (a verb phrase in the terminology used above; that is, a verb together with its objects and complements). A dependent clause also normally contains a subordinating conjunction (or in the case of relative clauses, a relative pronoun or phrase containing one). English syntax is essentially of SVO (subject–verb–object) type; the verb precedes its object in the verb phrase, and the subject of the clause precedes the verb.

Questions

Like many other Western European languages, English historically allowed questions to be asked by inverting the positions of verb and subject. Modern English requires the use of the auxiliary verb do, along with inversion of the word order, to form a question from a simple (one-word) affirmative (I goDo I go?, Where do I go?), apart from when the main verb is "be" (I am hereAm I here?, Why am I here?). When the affirmative verb is compound, a question is formed by inverting the auxiliary verb with the subject (John is goingIs John going?).
Combining the formation of a question with negation involves both insertion of do, if the verb is not already compound, and inversion of the auxiliary verb with the subject: John is goingIs John not going?; John goesDoes John not go?. However, the word not can optionally (especially in informal English) be contracted with the auxiliary verb, in which case the word order is further changed: Isn't John going?, Doesn't John go?.

Dependent clauses

The syntax of a dependent clause is generally the same as that of an independent clause, except that the dependent clause usually begins with a subordinating conjunction or relative pronoun (or phrase containing such). In some situations (as already described) the conjunction or relative pronoun that can be omitted. Another type of dependent clause with no subordinating conjunction is the conditional clause formed by inversion (see below).

Other uses of inversion

The clause structure with inverted subject and verb, used to form questions as described above, is also used in certain types of declarative sentence. This occurs mainly when the sentence begins with an adverbial or other phrase that is essentially negative or contains words such as only, hardly, etc.: Never have I known someone so stupid; Only in France can such food be tasted.
In elliptical sentences (see below), inversion takes place after so (meaning "also") as well as after the negative neither: so do I, neither does she.
Inversion can also be used to form conditional clauses, beginning with should, were (subjunctive), or had, in the following ways:
  • should I win the race (equivalent to if I win the race);
  • were he a soldier (equivalent to if he were a soldier);
  • were he to win the race (equivalent to if he were to win the race, i.e. if he won the race);
  • had he won the race (equivalent to if he had won the race).
Other similar forms sometimes appear, but are less common. There is also a construction with subjunctive be, as in be he alive or dead (meaning "no matter whether he is alive or dead").
Use of inversion to express a third-person imperative is now mostly confined to the expression long live X, meaning "let X live long".

Imperatives

In an imperative sentence (one giving an order), there is usually no subject in the independent clause: Go away until I call you. It is possible, however, to include you as the subject for emphasis: You stay away from me.

Elliptical constructions

Many types of elliptical construction are possible in English, resulting in sentences that omit certain redundant elements. Various examples are given in the article on Ellipsis.
Some notable elliptical forms found in English include:
  • Short statements of the form I can, he isn't, we mustn't. Here the verb phrase (understood from the context) is reduced to a single auxiliary or other "special" verb, negated if appropriate. If there is no special verb in the original verb phrase, it is replaced by do/does/did: he does, they didn't.
  • Clauses that omit the verb, in particular those like me too, nor me, me neither. The latter forms are used after negative statements. (Equivalents including the verb: I do too or so do I; I don't either or neither do I.)
  • Tag questions, formed with a special verb and pronoun subject: isn't it?; were there?; am I not?

History of English grammars

The first published English grammar was a Pamphlet for Grammar of 1586, written by William Bullokar with the stated goal of demonstrating that English was just as rule-based as Latin. Bullokar's grammar was faithfully modeled on William Lily's Latin grammar, Rudimenta Grammatices (1534), used in English schools at that time, having been "prescribed" for them in 1542 by Henry VIII. Bullokar wrote his grammar in English and used a "reformed spelling system" of his own invention; but many English grammars, for much of the century after Bullokar's effort, were written in Latin, especially by authors who were aiming to be scholarly. John Wallis's Grammatica Linguae Anglicanae (1685) was the last English grammar written in Latin.
Even as late as the early 19th century, Lindley Murray, the author of one of the most widely used grammars of the day, was having to cite "grammatical authorities" to bolster the claim that grammatical cases in English are different from those in Ancient Greek or Latin.



>Her Dream Bicycle

Bicycle

 
A bicycle, often called a bike[1] (and sometimes referred to as a "pushbike",[2] "pedal bike",[3] "pedal cycle",[4] or "cycle"[5]), is a human-powered, pedal-driven, single-track vehicle, having two wheels attached to a frame, one behind the other.[6] A person who rides a bicycle is called a cyclist, or bicyclist.
Bicycles were introduced in the 19th century and now number more than a billion worldwide, twice as many as automobiles.[7] They are the principal means of transportation in many regions. They also provide a popular form of recreation, and have been adapted for such uses as children's toys, adult fitness, military and police applications, courier services and bicycle racing.
The basic shape and configuration of a typical upright bicycle has changed little since the first chain-driven model was developed around 1885.[8] However, many details have been improved, especially since the advent of modern materials and computer-aided design. These have allowed for a proliferation of specialized designs for diverse types of cycling.
The invention of the bicycle has had an enormous effect on society, both in terms of culture and of advancing modern industrial methods. Several components that eventually played a key role in the development of the automobile were invented for the bicycle, including ball bearings, pneumatic tires, chain-driven sprockets, and tension-spoked wheels.[9]

 

Etymology

The word bicycle was coined by the Belgian newspaper La Gaulois in the 1890s.[10] Before that, and in some places thereafter, bikes were known primarily as velocipedes.

History

Wooden draisine (around 1820), the first two-wheeler and as such the archetype of the bicycle
The dandy horse, also called Draisienne or laufmaschine, was the first human means of transport to use only two wheels in tandem and was invented by the German Baron Karl von Drais. It is regarded as the forerunner of the modern bicycle and was introduced by Drais to the public in Mannheim in summer 1817 and in Paris in 1818.[11] Its rider sat astride a wooden frame supported by two in-line wheels and pushed the vehicle along with his/her feet while steering the front wheel.

Michaux' son on velocipede 1868
Thomas McCall in 1869 on his velocipede
The first mechanically-propelled 2-wheel vehicle may have been built by Kirkpatrick MacMillan, a Scottish blacksmith, in 1839, although the claim is open to dispute.[12] He is also associated with the first recorded instance of a cycling traffic offence, when a Glasgow newspaper in 1842 reported an accident in which an anonymous "gentleman from Dumfries-shire... bestride a velocipede... of ingenious design" knocked over a little girl in Glasgow and was fined five shillings.[13]
In the early 1860s, Frenchmen Pierre Michaux and Pierre Lallement took bicycle design in a new direction by adding a mechanical crank drive with pedals on an enlarged front wheel (the velocipede). Another French inventor by the name of Douglas Grasso had a failed prototype of Pierre Lallement's bicycle several years earlier. Several inventions followed using rear-wheel drive, the best known being the rod-driven velocipede by Scotsman Thomas McCall in 1869. The French creation, made of iron and wood, developed into the "penny-farthing" (historically known as an "ordinary bicycle", a retronym, since there was then no other kind).[14] It featured a tubular steel frame on which were mounted wire-spoked wheels with solid rubber tires. These bicycles were difficult to ride due to their high seat and poor weight distribution. In 1868 a Michaux cycle was brought to Coventry, England by Rowley Turner, sales agent of the Coventry Sewing Machine Company (which soon became the Coventry Machinist Company). His uncle, Josiah Turner, together with business partner James Starley used this as a basis for the 'Coventry Model' in what became Britain's first cycle factory.[15]

A penny-farthing or ordinary bicycle photographed in the Škoda Auto museum in the Czech Republic

Bicycle in Plymouth, England at the start of the 20th century
The dwarf ordinary addressed some of these faults by reducing the front wheel diameter and setting the seat further back. This necessitated the addition of gearing, effected in a variety of ways, to efficiently use the power available. Having to both pedal and steer via the front wheel remained a problem. J. K. Starley (nephew of James Starley), J. H. Lawson, and Shergold solved this problem by introducing the chain drive (originated by the unsuccessful "bicyclette" of Englishman Henry Lawson),[16] connecting the frame-mounted cranks to the rear wheel. These models were known as dwarf safeties, or safety bicycles, for their lower seat height and better weight distribution (although without pneumatic tires the ride of the smaller-wheeled bicycle would be much rougher than that of the larger-wheeled variety). Starley's 1885 Rover, manufactured in Coventry, England,[17] is usually described as the first recognizably modern bicycle. Soon, the seat tube was added, creating the double-triangle diamond frame of the modern bike.
Further innovations increased comfort and ushered in a second bicycle craze, the 1890s' Golden Age of Bicycles. In 1888, Scotsman John Boyd Dunlop introduced the first practical pneumatic tire, which soon became universal. Soon after, the rear freewheel was developed, enabling the rider to coast. This refinement led to the 1890s invention[18] of coaster brakes. Derailleur gears and hand-operated cable-pull brakes were also developed during these years, but were only slowly adopted by casual riders. By the turn of the century, cycling clubs flourished on both sides of the Atlantic, and touring and racing became widely popular.
Bicycles and horse buggies were the two mainstays of private transportation just prior to the automobile, and the grading of smooth roads in the late 19th century was stimulated by the widespread advertising, production, and use of these devices.[19]

Uses

Bicycles have been and are employed for many uses:
  • Utility: transportation, bicycle commuting, and utility cycling
  • Work: mail delivery, paramedics, police, couriering, and general delivery.
  • Recreation: bicycle touring, mountain biking, BMX, physical fitness, and play.
  • Racing: track racing, criterium, roller racing and time trial to multi-stage events like the Tour of California, Giro d'Italia, the Tour de France, the Vuelta a España, the Volta a Portugal, among others.
  • Military: scouting, troop movement, supply of provisions, and patrol. See bicycle infantry.
  • Show: entertainment and performance, e.g. Artistic cyclings.

Technical aspects


A Half Wheeler trailer bike at the Golden Gate Bridge
The bicycle has undergone continual adaptation and improvement since its inception. These innovations have continued with the advent of modern materials and computer-aided design, allowing for a proliferation of specialized bicycle types.

Types


A BMX bike, an example of a bicycle designed for sport
Bicycles can be categorized in different ways: e.g. by function, by number of riders, by general construction, by gearing or by means of propulsion. The more common types include utility bicycles, mountain bicycles, racing bicycles, touring bicycles, hybrid bicycles, cruiser bicycles, and BMX Bikes. Less common are tandems, lowriders, tall bikes, fixed gear, folding models, amphibious bicycles and recumbents (one of which was used to set the IHPVA Hour record).
Unicycles, tricycles and quadracycles are not strictly bicycles, as they have respectively one, three and four wheels, but are often referred to informally as "bikes".

Bicycles leaning in a turn

Dynamics

A bicycle stays upright while moving forward by being steered so as to keep its center of mass over the wheels.[20] This steering is usually provided by the rider, but under certain conditions may be provided by the bicycle itself.[21]
The combined center of mass of a bicycle and its rider must lean into a turn to successfully navigate it. This lean is induced by a method known as countersteering, which can be performed by the rider turning the handlebars directly with the hands[22] or indirectly by leaning the bicycle.[23]
Short-wheelbase or tall bicycles, when braking, can generate enough stopping force at the front wheel to flip longitudinally.[24] The act of purposefully using this force to lift the rear wheel and balance on the front without tipping over is a trick known as a stoppie, endo or front wheelie.

Performance

The bicycle is extraordinarily efficient in both biological and mechanical terms. The bicycle is the most efficient human-powered means of transportation in terms of energy a person must expend to travel a given distance.[25] From a mechanical viewpoint, up to 99% of the energy delivered by the rider into the pedals is transmitted to the wheels, although the use of gearing mechanisms may reduce this by 10–15%.[26][27] In terms of the ratio of cargo weight a bicycle can carry to total weight, it is also an efficient means of cargo transportation.

A recumbent bicycle
A human traveling on a bicycle at low to medium speeds of around 10–15 mph (15–25 km/h) uses only the energy required to walk. Air drag, which is proportional to the square of speed, requires dramatically higher power outputs as speeds increase. If the rider is sitting upright, the rider's body creates about 75% of the total drag of the bicycle/rider combination. Drag can be reduced by seating the rider in a more aerodynamically streamlined position. Drag can also be reduced by covering the bicycle with an aerodynamic fairing.
In addition, the carbon dioxide generated in the production and transportation of the food required by the bicyclist, per mile traveled, is less than 1/10 that generated by energy efficient cars.[28]

Construction and parts

In its early years, bicycle construction drew on pre-existing technologies. More recently, bicycle technology has in turn contributed ideas in both old and new areas.

Frame


Diagram of a bicycle.
 File:Bicycle diagram-en.svg
The great majority of today's bicycles have a frame with upright seating which looks much like the first chain-driven bike.[8] Such upright bicycles almost always feature the diamond frame, a truss consisting of two triangles: the front triangle and the rear triangle. The front triangle consists of the head tube, top tube, down tube and seat tube. The head tube contains the headset, the set of bearings that allows the fork to turn smoothly for steering and balance. The top tube connects the head tube to the seat tube at the top, and the down tube connects the head tube to the bottom bracket. The rear triangle consists of the seat tube and paired chain stays and seat stays. The chain stays run parallel to the chain, connecting the bottom bracket to the rear fork ends. The seat stays connect the top of the seat tube (at or near the same point as the top tube) to the rear fork ends.
 


A Triumph with a step-through frame.
Historically, women's bicycle frames had a top tube that connected in the middle of the seat tube instead of the top, resulting in a lower standover height at the expense of compromised structural integrity, since this places a strong bending load in the seat tube, and bicycle frame members are typically weak in bending. This design, referred to as a step-through frame, allows the rider to mount and dismount in a dignified way while wearing a skirt or dress. While some women's bicycles continue to use this frame style, there is also a variation, the mixte, which splits the top tube laterally into two thinner top tubes that bypass the seat tube on each side and connect to the rear fork ends. The ease of stepping through is also appreciated by those with limited flexibility or other joint problems. Because of its persistent image as a "women's" bicycle, step-through frames are not common for larger frames.
Another style is the recumbent bicycle. These are inherently more aerodynamic than upright versions, as the rider may lean back onto a support and operate pedals that are on about the same level as the seat. The world's fastest bicycle is a recumbent bicycle but this type was banned from competition in 1934 by the Union Cycliste Internationale.[29]
Historically, materials used in bicycles have followed a similar pattern as in aircraft, the goal being high strength and low weight. Since the late 1930s alloy steels have been used for frame and fork tubes in higher quality machines. Celluloid found application in mudguards, and aluminum alloys are increasingly used in components such as handlebars, seat post, and brake levers. In the 1980s aluminum alloy frames became popular for their lightness, and their affordability now makes them common. More expensive carbon fiber and titanium frames are now also available, as well as advanced steel alloys and even bamboo.[30]

Drivetrain and gearing


A set of rear sprockets (also known as a cassette) and a derailleur
The drivetrain begins with pedals which rotate the cranks, which are held in axis by the bottom bracket. Most bicycles use a chain to transmit power to the rear wheel. A relatively small number of bicycles use a shaft drive to transmit power. A very small number of bicycles (mainly single-speed bicycles intended for short-distance commuting) use a belt drive as an oil-free way of transmitting power.
Since cyclists' legs are most efficient over a narrow range of pedaling speeds (cadence), a variable gear ratio helps a cyclist to maintain an optimum pedalling speed while covering varied terrain. As a first approximation, utility bicycles often use a hub gear with a small number (3 to 8) of widely spaced gears, road bicycles and racing bicycles use derailleur gears with a moderate number (10 to 22) of closely spaced gear ratios, while mountain bicycles, hybrid bicycles, and touring bicycles use dérailleur gears with a larger number (15 to 33) of moderately spaced gear ratios, often including an extremely low gear ("granny gear") for climbing steep hills.
Different gears and ranges of gears are appropriate for different people and styles of cycling. Multi-speed bicycles allow gear selection to suit the circumstances: a cyclist could use a high gear when cycling downhill, a medium gear when cycling on a flat road, and a low gear when cycling uphill. In a lower gear every turn of the pedals leads to fewer rotations of the rear wheel. This allows the energy required to move the same distance to be distributed over more pedal turns, reducing fatigue when riding uphill, with a heavy load, or against strong winds. A higher gear allows a cyclist to make fewer pedal turns to maintain a given speed, but with more effort per turn of the pedals.

A bicycle with shaft drive instead of a chain
With a chain drive transmission, a chainring attached to a crank drives the chain, which in turn rotates the rear wheel via the rear sprocket(s) (cassette or freewheel). There are four gearing options: two-speed hub gear integrated with chain ring, up to 3 chain rings, up to 11 sprockets, hub gear built in to rear wheel (3-speed to 14-speed). The most common options are either a rear hub or multiple chain rings combined with multiple sprockets (other combinations of options are possible but less common).
With a shaft drive transmission, a gear set at the bottom bracket turns the shaft, which then turns the rear wheel via a gear set connected to the wheel's hub. There is some small loss of efficiency due to the two gear sets needed. The only gearing option with a shaft drive is to use a hub gear.

Steering and seating

The handlebars turn the fork and the front wheel via the stem, which rotates within the headset. Three styles of handlebar are common. Upright handlebars, the norm in Europe and elsewhere until the 1970s, curve gently back toward the rider, offering a natural grip and comfortable upright position. Drop handlebars "drop" as they curve forward and down, offering the cyclist best braking power from a more aerodynamic "crouched" position, as well as more upright positions in which the hands grip the brake lever mounts, the forward curves, or the upper flat sections for increasingly upright postures. Mountain bikes generally feature a 'straight handlebar' or 'riser bar' with varying degrees of sweep backwards and centimeters rise upwards, as well as wider widths which can provide better handling due to increased leverage against the wheel.

A Selle San Marco saddle designed for women
Saddles also vary with rider preference, from the cushioned ones favored by short-distance riders to narrower saddles which allow more room for leg swings. Comfort depends on riding position. With comfort bikes and hybrids, cyclists sit high over the seat, their weight directed down onto the saddle, such that a wider and more cushioned saddle is preferable. For racing bikes where the rider is bent over, weight is more evenly distributed between the handlebars and saddle, the hips are flexed, and a narrower and harder saddle is more efficient. Differing saddle designs exist for male and female cyclists, accommodating the genders' differing anatomies, although bikes typically are sold with saddles most appropriate for men.
A recumbent bicycle has a reclined chair-like seat that some riders find more comfortable than a saddle, especially riders who suffer from certain types of seat, back, neck, shoulder, or wrist pain. Recumbent bicycles may have either under-seat or over-seat steering.

Brakes


Linear-pull brake, also known by the Shimano trademark: V-Brake, on rear wheel of a mountain bike
Modern bicycle brakes may be: rim brakes, in which friction pads are compressed against the wheel rims; internal hub brakes, in which the friction pads are contained within the wheel hubs; or disc brakes, with a separate rotor for braking. Disc brakes are more common for off-road bicycles, tandems and recumbent bicycles than on road-specific bicycles.

A front disc brake, mounted to the fork and hub
With hand-operated brakes, force is applied to brake levers mounted on the handlebars and transmitted via Bowden cables or hydraulic lines to the friction pads. A rear hub brake may be either hand-operated or pedal-actuated, as in the back pedal coaster brakes which were popular in North America until the 1960s, and are common in children's bicycles.
Track bicycles do not have dedicated brakes. Brakes are not required for riding on a track because all riders ride in the same direction around a track which does not necessitate sharp deceleration. Track riders are still able to slow down because all track bicycles are fixed-gear, meaning that there is no freewheel. Without a freewheel, coasting is impossible, so when the rear wheel is moving, the crank is moving. To slow down, the rider applies resistance to the pedals – this acts as a braking system which can be as effective as a friction-based rear wheel brake, but not as effective as a front wheel brake.[31]

Suspension

Bicycle suspension refers to the system or systems used to suspend the rider and all or part of the bicycle. This serves two purposes:
  • To keep the wheels in continuous contact with rough surfaces to improve control.
  • To isolate the rider and luggage from jarring due to rough surfaces.
Bicycle suspensions are used primarily on mountain bicycles, but are also common on hybrid bicycles, and can even be found on some road bicycles, as they can help deal with problematic vibration. Suspension is especially important on recumbent bicycles, since while an upright bicycle rider can stand on the pedals to achieve some of the benefits of suspension, a recumbent rider cannot.

Wheels and tires

The wheel axle fits into fork ends in the frame and fork. A pair of wheels may be called a wheelset, especially in the context of ready-built "off the shelf", performance-oriented wheels.
Tires vary enormously. Skinny 18 to 25 millimeters wide, road-racing tires may be completely smooth, or slick. On the opposite extreme, off-road tires are 38 to 64 millimeters wide and usually have a deep tread for gripping in muddy conditions or metal studs for ice.

Accessories, repairs, and tools


Touring bicycle equipped with front and rear racks, fenders/mud-guards, water bottles in cages, four panniers and a handlebar bag.

Puncture repair kit with tire levers, sandpaper to clean off an area of the inner tube around the puncture, a tube of rubber solution (vulcanizing fluid), round and oval patches, a metal grater and piece of chalk to make chalk powder (to dust over excess rubber solution). Kits often also include a wax crayon to mark the puncture location.
Some components, which are often optional accessories on sports bicycles, are standard features on utility bicycles to enhance their usefulness and comfort. Mudguards, or fenders, protect the cyclist and moving parts from spray when riding through wet areas and chainguards protect clothes from oil on the chain while preventing clothing from being caught between the chain and crankset teeth. Kick stands keep a bicycle upright when parked, while a bike lock will help prevent it from being stolen. Front-mounted baskets for carrying goods are often used. Luggage carriers and panniers mounted above the rear tire can be used to carry equipment or cargo. Parents sometimes add rear-mounted child seats and/or an auxiliary saddle fitted to the crossbar to transport children.
Toe-clips and toestraps and clipless pedals help keep the foot locked in the proper position on the pedals, and enable the cyclist to pull as well as push the pedals—although not without their hazards, e.g. may lock foot in when needed to prevent a fall. Technical accessories include cyclocomputers for measuring speed, distance, heart rate, GPS data etc. Other accessories include lights, reflectors, security locks, mirror, water bottles and cages, and bell.[32]
Bicycle helmets may help reduce injury in the event of a collision or accident, and a certified helmet is legally required for some riders in some jurisdictions. Helmets are classified as an accessory[32] or an item of clothing by others.[33]
Many cyclists carry tool kits. These may include a tire patch kit (which, in turn, may contain any combination of a hand pump or CO2 Pump, tire levers, spare tubes, self-adhesive patches, or tube-patching material, an adhesive, a piece of sandpaper or a metal grater (for roughing the tube surface to be patched),[34][35] and sometimes even a block of French chalk.), wrenches, hex keys, screwdrivers, and a chain tool. There are also cycling specific multi-tools that combine many of these implements into a single compact device. More specialized bicycle components may require more complex tools, including proprietary tools specific for a given manufacturer.
Some bicycle parts, particularly hub-based gearing systems, are complex, and many cyclists prefer to leave maintenance and repairs to professional bicycle mechanics. In some areas it is possible to purchase road-side assistance from companies such as the Better World Club. Other cyclists maintain their own bicycles, perhaps as part of their enjoyment of the hobby of cycling or simply for economic reasons. A cyclist's ability to repair and maintain their own bicycle is also celebrated within the DIY movement.

Standards

A number of formal and industry standards exist for bicycle components to help make spare parts exchangeable and to maintain a minimum product safety.
The International Organization for Standardization, ISO, has a special technical committee for cycles, TC149, that has the following scope: "Standardization in the field of cycles, their components and accessories with particular reference to terminology, testing methods and requirements for performance and safety, and interchangeability."
CEN, European Committee for Standardisation, also has a specific Technical Committee, TC333, that defines European standards for cycles. Their mandate states that EN cycle standards shall harmonize with ISO standards. Some CEN cycle standards were developed before ISO published their standards, leading to strong European influences in this area. European cycle standards tend to describe minimum safety requirements, while ISO standards have historically harmonized parts geometry.[36]

Parts

For details on specific bicycle parts, see list of bicycle parts and category:bicycle parts.

Social and historical aspects

The bicycle has had a considerable effect on human society, in both the cultural and industrial realms.

In daily life

Around the turn of the 20th century, bicycles reduced crowding in inner-city tenements by allowing workers to commute from more spacious dwellings in the suburbs. They also reduced dependence on horses. Bicycles allowed people to travel for leisure into the country, since bicycles were three times as energy efficient as walking and three to four times as fast.

A bike-sharing station in Barcelona
Recently,[when?] several European and North American cities have implemented successful schemes known as community bicycle programs or bike-sharing.[37][38] These initiatives complement a city's public transport system and offer an alternative to motorized traffic to help reduce congestion and pollution.[39] In Europe, especially in The Netherlands and parts of Germany and Denmark, commuting by bicycle is very common. In the Danish capital of Copenhagen, a cyclists' organization runs a Cycling Embassy, that promotes biking for commuting and sightseeing. The United Kingdom has a tax break scheme (IR 176) that allows employees to buy a new bicycle tax free to use for commuting.[40]
In The Netherlands, all train stations are equipped with provisions for bicycle parking for free or a more secure parking place for a small fee and the larger ones also with bicycle repair shops, and cycling is so popular that the parking capacity is sometimes exceeded. In Delft the capacity is usually exceeded.[41] In Trondheim in Norway, the Trampe bicycle lift has been developed to encourage cyclists by giving assistance on a steep hill. Buses in many cities have bicycle carriers mounted on the front.
There are towns in some countries where bicycle culture has been an integral part of the landscape for generations, even without much official support. That is the case of Ílhavo, in Portugal.
In cities where the bicycle is not an integral part of the planned transportation system, commuters often use bicycles as elements of a mixed-mode commute, where the bike is used to travel to and from train stations or other forms of rapid transit. Some students who commute several miles drive a car from home to a campus parking lot, then ride a bicycle to class. Folding bicycles are useful in these scenarios, as they are less cumbersome when carried aboard. Los Angeles removed a small amount of seating on some trains to make more room for bicycles and wheel chairs.[42]

Bike racks in Vancouver, British Columbia
Some US companies, notably in the tech sector, are developing both innovative cycle designs and cycle-friendliness in the workplace. Google is working to encourage use of a seven-person four-wheel[43] "Conference Bike", employing riders' muscle energy while also allowing conversational interaction. Foursquare, whose CEO Dennis Crowley "pedaled to pitch meetings ... [when he] was raising money from venture capitalists" on a two-wheeler, chose a new location for its New York headquarters "based on where biking would be easy". Parking in the office was also integral to HQ planning. Mitchell Moss, who runs the Rudin Center for Transportation Policy & Management at New York University, said in 2012: "Biking has become the mode of choice for the educated high tech worker."[44]
Bicycles offer an important mode of transport in many developing countries. Until recently, bicycles have been a staple of everyday life throughout Asian countries. They are the most frequently used method of transport for commuting to work, school, shopping, and life in general. They also offer a degree of exercise to keep the individual healthy. [45]
Bicycles are also celebrated through use of visual art. An example of bicycles being appreciated through use of art, music, and film is the Bicycle Film Festival, a film festival hosted all around the world.

Poverty alleviation

Experiments done in Africa (Uganda and Tanzania) and Sri Lanka on hundreds of households have shown that a bicycle can increase the income of a poor family by as much as 35%.[46][47][48] Transport, if analyzed for the cost-benefit analysis for rural poverty alleviation, has given one of the best returns in this regard. For example, road investments in India were a staggering 3-10 times more effective than almost all other investments and subsidies in rural economy in the decade of 1990s. What a road does at a macro level to increase transport, the bicycle supports at the micro level. The bicycle, in that sense, can be one of the best means to eradicate poverty in poor nations.

Female emancipation


Woman with bicycle, 1890s
The safety bicycle gave women unprecedented mobility, contributing to their emancipation in Western nations. As bicycles became safer and cheaper, more women had access to the personal freedom they embodied, and so the bicycle came to symbolize the New Woman of the late 19th century, especially in Britain and the United States.
The bicycle was recognized by 19th-century feminists and suffragists as a "freedom machine" for women. American Susan B. Anthony said in a New York World interview on February 2, 1896: "Let me tell you what I think of bicycling. I think it has done more to emancipate women than anything else in the world. It gives women a feeling of freedom and self-reliance. I stand and rejoice every time I see a woman ride by on a wheel... the picture of free, untrammeled womanhood." In 1895 Frances Willard, the tightly laced president of the Women’s Christian Temperance Union, wrote a book called How I Learned to Ride the Bicycle, in which she praised the bicycle she learned to ride late in life, and which she named "Gladys", for its "gladdening effect" on her health and political optimism. Willard used a cycling metaphor to urge other suffragists to action, proclaiming, "I would not waste my life in friction when it could be turned into momentum."
The bicycle craze in the 1890s also led to a movement for so-called rational dress, which helped liberate women from corsets and ankle-length skirts and other restrictive garments, substituting the then-shocking bloomers.

Economic implications


Columbia Bicycles advertisement from 1886
Bicycle manufacturing proved to be a training ground for other industries and led to the development of advanced metalworking techniques, both for the frames themselves and for special components such as ball bearings, washers, and sprockets. These techniques later enabled skilled metalworkers and mechanics to develop the components used in early automobiles and aircraft.
They also served to teach the industrial models later adopted, including mechanization and mass production (later copied and adopted by Ford and General Motors),[49] vertical integration[50] (also later copied and adopted by Ford), aggressive advertising[51] (as much as 10% of all advertising in U.S. periodicals in 1898 was by bicycle makers),[52] lobbying for better roads (which had the side benefit of acting as advertising, and of improving sales by providing more places to ride),[53] all first practised by Pope.[53] In addition, bicycle makers adopted the annual model change[54][55] (later derided as planned obsolescence, and usually credited to General Motors), which proved very successful.[56]
Furthermore, early bicycles were an example of conspicuous consumption, being adopted by the fashionable elites.[57] In addition, by serving as a platform for accessories, which could ultimately cost more than the bicycle itself, it paved the way for the likes of the Barbie doll.[58]
Moreover, they helped create, or enhance, new kinds of businesses, such as bicycle messengers,[59] travelling seamstresses,[60] riding academies,[61] and racing rinks[62] (Their board tracks were later adapted to early motorcycle and automobile racing.) Also, there were a variety of new inventions, such as spoke tighteners,[63] and specialized lights,[64] socks and shoes,[65] and even cameras (such as the Eastman Company's Poco).[66] Probably the best known and most widely used of these inventions, adopted well beyond cycling, is Charles Bennett's Bike Web, which came to be called the "jock strap".[67]

A man uses a bicycle to carry goods in Ouagadougou, Burkina Faso
They also presaged a move away from public transit[68] that would explode with the introduction of the automobile.
J. K. Starley's company became the Rover Cycle Company Ltd. in the late 1890s, and then simply the Rover Company when it started making cars. Morris Motors LImited (in Oxford) and Škoda also began in the bicycle business, as did the Wright brothers.[69] Alistair Craig, whose company eventually emerged to become the engine manufacturers Ailsa Craig, also started from manufacturing bicycles, in Glasgow in March 1885.
In general, U.S. and European cycle manufacturers used to assemble cycles from their own frames and components made by other companies, although very large companies (such as Raleigh) used to make almost every part of a bicycle (including bottom brackets, axles, etc.) In recent years, those bicycle makers have greatly changed their methods of production. Now, almost none of them produce their own frames.
Many newer or smaller companies only design and market their products; the actual production is done by Asian companies. For example, some 60% of the world's bicycles are now being made in China. Despite this shift in production, as nations such as China and India become more wealthy, their own use of bicycles has declined due to the increasing affordability of cars and motorcycles.[70] One of the major reasons for the proliferation of Chinese-made bicycles in foreign markets is the lower cost of labor in China.[71]
One of the profound economic implications of bicycle use is that it liberates the user from oil consumption (Ballantine, 1972). The bicycle is an inexpensive, fast, healthy and environmentally friendly mode of transport (Illich, 1974)

Manufacturing

The global bicycle market is $61 billion in 2011.[72] 130 million bicycles are sold every year globally and 66% of them are made in China.[73]

Legal requirements

Early in its development, as with automobiles, there were restrictions on the operation of bicycles. Along with advertising, and to gain free publicity, Albert A. Pope litigated on behalf of cyclists.[74]
The 1968 Vienna Convention on Road Traffic of the United Nations considers a bicycle to be a vehicle, and a person controlling a bicycle (whether actually riding or not) is considered an operator. The traffic codes of many countries reflect these definitions and demand that a bicycle satisfy certain legal requirements before it can be used on public roads. In many jurisdictions, it is an offense to use a bicycle that is not in a roadworthy condition.
In most jurisdictions, bicycles must have functioning front and rear lights when ridden after dark. As some generator or dynamo-driven lamps only operate while moving, rear reflectors are frequently also mandatory. Since a moving bicycle makes little noise, some countries insist that bicycles have a warning bell for use when approaching pedestrians, equestrians, and other cyclists, though sometimes a car horn can be used when a 12 volt battery is available.
Some countries require child and/or adult cyclists to wear helmets, as this may protect riders from head trauma. Countries which require adult cyclists to wear helmets include Spain, New Zealand and Australia. Mandatory helmet wearing is one of the most controversial topics in the cycling world, with proponents arguing that it reduces head injuries and thus is an acceptable requirement, while opponents argue that by making cycling seem more dangerous and cumbersome, it reduces cyclist numbers on the streets, creating an overall negative health effect (fewer people cycling for their own health, and the remaining cyclists being more exposed through a reversed safety in numbers effect).