Derailleur gears several standards in use, and in each the product of the derailleur's actuation ratio and the length of cable pulled must equal the pitch of the rear sprockets. The following standards exist. Some rear derailleurs, especially for mountain bikes, incorporate a clutch to keep the lower length of chain in sufficient tension to prevent the chain from striking the bottom of the chain stay, called "chain slap", and which can damage the chain stay. Clutches are also helpful in preventing the chain from derailing from the chain ring on systems without a front derailleur. The front derailleur only has to
What Is Literature? The art of writing is deeply linked to freedom and thus ventures into the fields of politics and democracy. The poet frees himself by disassociation, and the prose writer fulfills a duty to utilize language for the end of a conceived free society. What Is Literature? What Is Literature? (), also published as "Literature and Existentialism",) is an essay by French philosopher and novelist Jean-Paul Sartre, published by Gallimard in 1948. Initially published in freestanding essays across French literary journals "Les Temps modernes", "Situations I" and "Situations II", essays "What is Writing?" and "Why Write?" were translated into English and