Derailleur gears chain slack. Cage length determines the total capacity of the derailleur, that is the size difference between the largest and smallest chainrings, and the size difference between the largest and smallest sprockets on the cogset added together. A larger sum requires a longer cage length. Typical cross country mountain bikes with three front chainrings will use a long cage rear derailleur. A road bike with only two front chainrings and close ratio sprockets can operate with either a short or long cage derailleur, but will work better with a short cage. Manufacturer stated derailleur capacities are as follows: Shimano long
Reaction mechanism bonds are broken (and in what order), and which bonds are formed (and in what order). A complete mechanism must also explain the reason for the reactants and catalyst used, the stereochemistry observed in reactants and products, all products formed and the amount of each. The electron or arrow pushing method is often used in illustrating a reaction mechanism; for example, see the illustration of the mechanism for benzoin condensation in the following examples section. A reaction mechanism must also account for the order in which molecules react. Often what appears to be a single-step conversion is in fact a