Derailleur gears operates the lever while pedalling, the change in cable tension moves the chain-guide from side to side, "derailing" the chain onto different sprockets. For more information about the choice of particular gear ratios and sprocket sizes, see Bicycle gearing. "Derailleur" is a French word, spelled "dérailleur" in French, derived from the derailment of a train from its tracks. Its first recorded use was 1930. At least one notable bicycle industry author has attempted to promote the anglicized spelling of "derailer". As of 2013, however, neither Merriam-Webster nor the Oxford English Dictionary has an entry for "derailer". Various derailleur systems were
Interrogative word Interrogative word An interrogative word or question word is a function word used to ask a question, such as "what", "when", "where", "who", "whom", "why", and "how". They are sometimes called wh-words, because in English most of them start with "wh-" (compare Five Ws). They may be used in both direct questions ("Where is he going?") and in indirect questions ("I wonder where he is going"). In English and various other languages the same forms are also used as relative pronouns in certain relative clauses ("The country where he was born") and certain adverb clauses ("I go where he goes").