The lower pulley on a rear derailer . So called because its main function is to adjust the tension on the chain as different-sized sprockets are selected. A line of bicycles designed specifically to meet the fitting needs of smaller women. Metric bolts are sized by the diameter and the distance between adjacent threads, for example 6 x 1 refers to a bolt 6mm in diameter with threads 1mm apart. A third system, known as Whitworth , was used in Britain up until the 1960's when they converted to metric.
Bicycle parts come in even more different thread systems than common nuts and bolts.
T.I.G. Welding T ungsten I nert G as welding . A form of welding by the use of an electric arc. T.I.G. welding is commonly used to build lugless bicycle frames. Most current bicycle frame production is done by T.I.G. welding. Three piece crank sets either use cotters or tapered cotterless attachment.