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
Influence of French on English linguist Henriette Walter, words of French origin represent more than two thirds of the English vocabulary. It is estimated by linguist Anthony Lacoudre that over 40 000 English words are directly French and may be understood without orthographical change by French speakers. At the beginning of 11th century, the English language did not have a well-defined status. Indeed, the inhabitants of what would become Great Britain did not have a language that allowed them to communicate with each other. There were many different dialectal forms. Great Britain, in which various Celtic idioms had coexisted since the fourth century, had experienced