Derailleur gears a detent or ratchet mechanism which stops the gear lever, and hence the cable and the derailleur, after moving a specific distance with each press or pull. Indexed shifters require re-calibration when cables stretch and parts get damaged or swapped. On racing bicycles, 10-gear rear cassettes appeared in 2000, and 11-gear cassettes appeared in 2009. Most current mountain bicycles have either. Many modern, high-end mountain bikes have begun using entirely one chain ring drivetrains, with the industry constantly pushing the number of rear cogs up and up, as shown by SRAM's Eagle groupsets (1 by 12) and Rotor's recent 1
Units of measurement in France before the French Revolution (league) had a number of variations, particularly the "aune" (which was used to measure cloth The "loi du 19 frimaire an VIII" (Law of 10 December 1799) states that one decimal metre is exactly 443.296 French lines, or "3 pieds 11.296 lignes de la "Toise du Pérou"". Thus the French royal foot is exactly 9000/27,706 metres (about 0.3248 m). In Quebec, the surveys in French units were converted using the relationship 1 "pied" (of the French variety, the same word being used for English feet as well) = 12.789 English inches. This makes the Quebec "pied" very slightly smaller (about