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 from the 1066 conquest that proto-English became massively impregnated with Old French, then modern French. It should be noted, however, that only French influenced English in the centuries following the conquest. The reverse contribution of English to French was only real from the eighteenth century. The arrival of William the Conqueror and his barons significantly changed the linguistic situation in England. Norman was essentially imposed in the upper layers of society. The Anglo-Saxon dialects were supplanted by Norman in the circles of the court and aristocracy, justice and the Church. The influential circles, who came from Normandy and settled in